U.S. patent application number 13/510613 was filed with the patent office on 2013-01-03 for downhole circulation apparatus.
This patent application is currently assigned to SCHOELLER BLECKMANN OILFIELD EQUIPMENT AG. Invention is credited to Paul Bernard Lee.
Application Number | 20130000923 13/510613 |
Document ID | / |
Family ID | 41509505 |
Filed Date | 2013-01-03 |
United States Patent
Application |
20130000923 |
Kind Code |
A1 |
Lee; Paul Bernard |
January 3, 2013 |
Downhole Circulation Apparatus
Abstract
A downhole circulation apparatus comprises at least one tubular
body portion defining a first through-flow passage through which
drilling fluid can pass along the drill string. A first sleeve is
slidably mounted in the tubular body portion and is biased into a
position in which the first port means is closed by a biasing means
such as a spring. Second port means is formed through the tubular
body portion at a location below the first port means in the drill
string. The second port means may comprise a plurality of second
nozzles, wherein each of the second nozzles has a diameter greater
than the diameter of each of the first nozzles of the first port
means. Larger nozzles enable large particle size drilling fluid to
be bypassed. A second sleeve is slidably mounted inside the tubular
body portion.
Inventors: |
Lee; Paul Bernard;
(Edmonton, CA) |
Assignee: |
SCHOELLER BLECKMANN OILFIELD
EQUIPMENT AG
Ternitz
AT
|
Family ID: |
41509505 |
Appl. No.: |
13/510613 |
Filed: |
November 17, 2010 |
PCT Filed: |
November 17, 2010 |
PCT NO: |
PCT/EP2010/067712 |
371 Date: |
September 17, 2012 |
Current U.S.
Class: |
166/373 ;
166/317; 166/318; 166/321; 175/317 |
Current CPC
Class: |
E21B 21/103 20130101;
E21B 37/08 20130101 |
Class at
Publication: |
166/373 ;
166/321; 166/318; 166/317; 175/317 |
International
Class: |
E21B 21/10 20060101
E21B021/10 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 18, 2009 |
GB |
0920109.6 |
Claims
1. A downhole circulation apparatus arranged to be mounted in a
drill string, the apparatus comprising: at least one tubular body
portion for mounting in a drill string, at least one said tubular
body portion defining a first through-flow passage for receiving a
flow of drilling fluid through the drill string; first port means
formed through at least one said tubular body portion; a first
sleeve slidably mounted inside at least one said tubular body
portion, the first sleeve moveable between a closed position in
which said first port means is closed by the first sleeve and an
open position in which said first port means is open to allow
drilling fluid in to circulate out of the apparatus; first biasing
means biasing the first sleeve into the closed position; second
port means formed through at least one said tubular body portion at
a location below the first port means when the apparatus is in use;
a second sleeve slidably mounted inside at least one said tubular
body portion, the second sleeve moveable between a closed position
in which said second port means is closed by the second sleeve and
an open position in which said second port means is open to allow
drilling fluid to circulate out of the apparatus; and second
biasing means biasing the second sleeve into the closed
position.
2. An apparatus according to claim 1, wherein at least one of the
first sleeve and the second sleeve comprises a flow responsive
portion responsive to a flow or a pressure of drilling fluid
through the first through-flow passage to be thereby movable
between the closed position and the open position depending on the
flow of drilling fluid.
3. An apparatus according to claim 2, comprising a first clutch
member secured to the at least one said tubular body portion and a
second clutch member axially spaced from the first clutch member
and secured to the at least one said tubular body portion, the
respective sleeve being axially arranged between the first clutch
member and the second clutch member and being movable between
cooperative engagement with the first clutch member or the second
clutch member, the cooperative engagement being controlled by an
indexable latch mechanism.
4. An apparatus according to claim 1, wherein at least one of the
first sleeve and the second sleeve comprises engagement means
configured for receiving a first restriction device; wherein the
apparatus comprises the first restriction device comprising a
second through-flow passage and configured so that dropping the
first restriction device into the apparatus causes the first
restriction device to engage the engagement means to cause an
increase in fluid pressure in the apparatus above the first
restriction device which moves the respective sleeve from the
closed to the open position; wherein the apparatus comprises a
second restriction device configured so that dropping the second
restriction device into the apparatus causes the second restriction
device to engage the first restriction device and block the second
through-flow passage to cause a fluid pressure increase in the
apparatus above the first and second restriction devices which
moves the first and second restriction devices past the respective
sleeve to cause the respective biasing means to move the respective
sleeve back to the closed position.
5. An apparatus according to claim 4, wherein the apparatus
comprises deactivation means configured so that dropping the
deactivation means into the apparatus closes the respective port
means to cause a further fluid pressure increase in the apparatus
above the first and second restriction devices which moves the
first and second restriction devices and the deactivation means
past the respective sleeve to cause the respective biasing means to
move the respective sleeve back to the closed position.
6. An apparatus according to claim 4, wherein the second
restriction device and/or the deactivation means is connected to a
wireline.
7. An apparatus according to claim 1, wherein at least one of the
first sleeve and the second sleeve comprises engagement means
configured for receiving activation means; wherein the apparatus
comprises the activation means configured so that dropping the
activation means into the apparatus causes the activation means to
engage the engagement means to cause an increase in fluid pressure
in the apparatus above the activation means which moves the
respective sleeve from the closed to the open position; wherein the
apparatus comprises deactivation means configured so that dropping
the deactivation means into the apparatus closes the respective
port means to cause a further fluid pressure increase in the
apparatus above the activation means which moves the activation
means and the deactivation means past the respective sleeve to
cause the respective biasing means to move the respective sleeve
back to the closed position.
8. An apparatus according to claim 7, wherein the apparatus
comprises locking means configured so that dropping the locking
means into the apparatus locks the respective port means open until
the deactivation means force the locking means to move out of the
port means towards an exterior of the tubular body portion.
9. An apparatus according to claim 1, wherein at least one of the
first sleeve and the second sleeve comprises engagement means
configured for receiving frangible activation means; wherein the
apparatus comprises the frangible activation means configured so
that dropping the frangible activation means into the apparatus
causes the frangible activation means to engage the engagement
means to cause an increase in fluid pressure in the apparatus above
the frangible activation means which moves the respective sleeve
from the closed to the open position; wherein the frangible
activation means is configured so that a further fluid pressure
increase in the apparatus above the frangible activation means
breaks the frangible activation means which thereby moves through
the engagement means to cause a decrease in fluid pressure in the
apparatus above the engagement means which moves the respective
sleeve from the closed to the open position.
10. An apparatus according to claim 1, wherein one of the first
sleeve and the second sleeve is configured according to claim 2,
and the other one of the first sleeve and the second sleeve is
configured according to claim 7; wherein the flow responsive
portion is dimensioned to be passable by the activation means.
11. An apparatus according to claim 1, wherein one of the first
sleeve and the second sleeve is configured according to claim 2,
and the other one of the first sleeve and the second sleeve is
configured according to claim 4; wherein the flow responsive
portion is dimensioned to be passable by the first restriction
device.
12. An apparatus according to claim 1, wherein the first sleeve and
the second sleeve are both configured according to claim 7; wherein
one or more ports of the first port means have a smaller dimension
than one or more ports of the second port means; wherein the
deactivation means for the first sleeve is dimensioned to pass
through the second port means.
13. An apparatus according to claim 1, wherein the first sleeve and
the second sleeve are both configured according to claim 9; wherein
the frangible activation means for the second sleeve is dimensioned
to pass through the engagement means of the first sleeve.
14. An apparatus according to claim 1, wherein the first sleeve and
the second sleeve are both configured according to claim 4; wherein
the first restriction device for the first sleeve is the first
restriction device for the second sleeve.
15. An apparatus according to claim 1, wherein the apparatus
comprises at least one restriction device configured so that
dropping the at least one restriction device into the apparatus
causes the at least one restriction device to engage first
engagement means of the first sleeve to cause an increase in fluid
pressure in the apparatus above the at least one restriction device
which moves the first sleeve from the closed to the open position;
and releasing the at least one restriction device from the first
engagement means of the first sleeve moves the at least one
restriction device down the apparatus to engage second engagement
means of the second sleeve to cause a fluid pressure increase in
the apparatus above the at least one restriction device to move the
second sleeve from the closed to the open position.
16. An apparatus according to claim 1, wherein the apparatus
comprises: third port means formed through at least one said
tubular body portion at a location below the second port means when
the apparatus is in use; a third sleeve slidably mounted inside at
least one said tubular body portion, the third sleeve moveable
between a closed position in which said third port means is closed
by the third sleeve and an open position in which said third port
means is open to allow drilling fluid to circulate out of the
apparatus; and third biasing means biasing the third sleeve into
the closed position.
17. An apparatus according to claim 1, wherein the apparatus is
arranged such that: a) dropping a first restriction device
comprising a second through-flow passage into the apparatus causes
the first restriction device to engage first engagement means of
said first sleeve to cause an increase in fluid pressure in the
apparatus above the first restriction device which moves the first
sleeve from the closed to the open position; b) dropping a second
restriction device into the apparatus after the first restriction
device has been dropped causes the second restriction device to
engage the first restriction device and block the second
through-flow passage to cause a fluid pressure increase in the
apparatus above the first and second restriction devices which
moves the first and second restriction devices past the first
sleeve to cause the first biasing means to move the first sleeve
back to the closed position; and c) wherein the first and second
restriction devices move down the apparatus to engage second
engagement means of said second sleeve to cause a fluid pressure
increase in the apparatus above the first and second restriction
devices to move the second sleeve from the closed to the open
position.
18. An apparatus according to claim 17, wherein the second sleeve
is moveable back to the closed position by said second biasing
means in response to dropping deactivation means into the apparatus
to block said second port means and cause a fluid pressure increase
in the apparatus to move the first and second restriction devices
past the second sleeve.
19. An apparatus according to claim 18, wherein the deactivation
means comprises at least one deactivation ball.
20. An apparatus according to claim 1, further comprising a
restriction device catcher located below said second sleeve when
the apparatus is in use.
21. An apparatus according to claim 1, wherein said first port
means comprises a plurality of first nozzles arranged to direct
drilling fluid into a drilled borehole in a direction opposite to
the direction of advancement of the apparatus.
22. An apparatus according to claim 21, wherein said plurality of
first nozzles is formed from tungsten carbide.
23. An apparatus according to claim 6, wherein the second port
means comprises a plurality of second nozzles, wherein each said
second nozzle has a diameter greater than the diameter of each of
said first nozzles.
24. An apparatus according to claim 17, wherein the first
restriction device is arranged to allow approximately 70% of the
fluid flow in the apparatus to pass through the second through-flow
passage when engaged with the first engagement means, such that
approximately 30% of the fluid flow in the apparatus is directed
through said first port means.
25. An apparatus according to claim 1, wherein the apparatus is
formed from an assembly of a plurality of drill string elements
comprising: a first tool element comprising a first tubular body
portion, first port means formed through said first tubular body
portion and a first sleeve slidably mounted inside said first
tubular body portion; a second tool element arranged below said
first tool element when the apparatus is in use, the second tool
element comprising a second tubular body portion, second port means
formed through said second tubular body portion and a second sleeve
slidably mounted inside said second tubular body portion; and at
least one drill pipe element disposed between and interconnecting
said first tool element with said second tool element.
26. An apparatus according to claim 25, further comprising a
plurality of drill pipe elements disposed between and
interconnecting said first tool element with said second tool
element.
27. An apparatus according to claim 17, wherein said first
restriction device is a dart comprising: a hollow body portion
defining said second through-flow passage; at least one deformable
portion arranged to engage the first and second engagement means of
the respective first and second sleeves; and a ball seat disposed
in the second through-flow passage, the ball seat arranged to
receive a ball to block said second through-flow passage.
28. An apparatus according to claim 27, wherein said dart further
comprises retention means disposed adjacent said ball seat, the
retention means arranged to prevent a ball located in the ball seat
from moving out of the ball seat in a first direction, but permit a
ball located in the ball seat to move past the ball seat in a
second direction.
29. An apparatus according to claim 28, wherein said retention
means comprises a plurality of teeth disposed on the hollow body
portion.
30. An apparatus according to claim 17, wherein said second
restriction device comprises a ball.
31. (canceled)
32. A downhole circulation system arranged such that a) dropping a
first restriction device comprising a second through-flow passage
into the apparatus causes the first restriction device to engage
first engagement means of said first sleeve to cause an increase in
fluid pressure in the apparatus above the first restriction device
which moves the first sleeve from the closed to the open position,
b) dropping a second restriction device into the apparatus after
the first restriction device has been dropped causes the second
restriction device to engage the first restriction device and block
the second through-flow passage to cause a fluid pressure increase
in the apparatus above the first and second restriction devices
which moves the first and second restriction devices past the first
sleeve to cause the first biasing means to move the first sleeve
back to the closed position, and c) wherein the first and second
restriction devices move down the apparatus to engage second
engagement means of said second sleeve to cause a fluid pressure
increase in the apparatus above the first and second restriction
devices to move the second sleeve from the closed to the open
position, the downhole circulation system, comprising: a first
restriction device comprising a second through-flow passage; and a
second restriction device adapted to engage said first restriction
device and block the second through-flow passage.
33. (canceled)
34. A method of operating a downhole circulation apparatus having
at least one tubular body portion for mounting in a drill string,
the at least one said tubular body portion defining a first
through-flow passage for receiving a flow of drilling fluid through
the drill string, first port means formed through at least one said
tubular body portion, a first sleeve slidably mounted inside at
least one said tubular body portion, the first sleeve moveable
between a closed position in which said first port means is closed
by the first sleeve and an open position in which said first port
means is open to allow drilling fluid to circulate out of the
apparatus, first biasing means biasing the first sleeve into the
closed position, second port means formed through at least one said
tubular body portion at a location below the first port means when
the apparatus is in use, a second sleeve slidably mounted inside at
least one said tubular body portion, the second sleeve moveable
between a closed position in which said second port means is closed
by the second sleeve and an open position in which said second port
means is open to allow drilling fluid to circulate out of the
apparatus and second biasing means biasing the second sleeve into
the closed position, the method comprising: a) causing an increase
in fluid pressure in the apparatus to move the first sleeve from
the closed to the open position; b) causing the first biasing means
to move the first sleeve back to the closed position; and c)
causing a fluid pressure increase in the apparatus to move the
second sleeve from the closed to the open position.
35. A method of claim 34, the method comprising: a) dropping a
first restriction device comprising a second through-flow passage
into the apparatus to cause the first restriction device to engage
first engagement means of said first sleeve and cause an increase
in fluid pressure in the apparatus above the first restriction
device to move the first sleeve from the closed to the open
position; b) dropping a second restriction device into the
apparatus after the first restriction device has been dropped to
cause the second restriction device to engage the first restriction
device and block the second through-flow passage to cause a fluid
pressure increase in the apparatus above the first and second
restriction devices which moves the first and second restriction
devices past the first sleeve and causes the first biasing means to
move the first sleeve back to the closed position; and c) wherein
the first and second restriction devices move down the apparatus to
engage second engagement means of said second sleeve to cause a
fluid pressure increase in the apparatus above the first and second
restriction devices to move the second sleeve from the closed to
the open position.
36. A method according to claim 35, further comprising: dropping at
least one deactivation means into the apparatus to block said
second port means and cause a fluid pressure increase in the
apparatus to move the first and second restriction devices past the
second sleeve and cause the second biasing means to move the second
sleeve back to the closed position.
37. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of the filing date of
British Patent Application GB 0920109.6 filed Nov. 18, 2009, the
disclosure of which is hereby incorporated herein by reference.
TECHNICAL FIELD
[0002] The present invention relates to a downhole circulation
apparatus arranged to be disposed in a drill string, and relates
particularly, but not exclusively, to a downhole circulation
apparatus which enables a drill string operator to both split the
flow of drilling fluid to increase flow rates and also enable the
operator to bypass large particle size drilling fluid to plug a
formation and prevent drilling fluid loss the formation.
BACKGROUND
[0003] In order to meet demand for energy the drilling of oil and
gas wells is becoming more and more complex in order to open up new
reserves. Wells can be drilled from land directionally and wells
are also being drilled in deeper and deeper formations.
[0004] A significant difficulty in extreme and complicated drilling
operations is the cleaning of the drilled hole. Drilled strata can
accumulate in the drilled well bore which can lead to a drill
string becoming stuck. Debris in the well bore can cause additional
torque on the drill string which can lead to drill string
failure.
[0005] There are already concepts for bore hole cleaning in the
prior art.
[0006] WO 01/06086 discloses a fluid flow actuated downhole tool
which is configurable in at least a first tool configuration and a
second tool configuration. The tool comprises a tubular housing and
an activating sleeve, the housing being adapted to catch the sleeve
when the sleeve is dropped from surface and the engagement of the
sleeve with the housing permitting actuation of the tool between
the first and second tool configurations. A flow restriction is
provided for permitting fluid flow actuation of the tool when the
activating sleeve has been caught in the body.
[0007] US 2004/0035586 discloses a method and an apparatus for
obstructing the passage of fluid within a fluid flow conduit and
subsequently reconfiguring the tool to allow substantially
full-bore passage therethrough. Pressure developed upstream of the
obstruction can be utilized to operate pressure actuated tools such
as liner hangers. Equipment used in subsequent well bore operations
such as drill pipe darts can pass undamaged through the opened
port. In an embodiment, the flow through a tubular is obstructed by
placing a ball on an expandable ball seat, developing a pressure
differential across the ball seat, equalizing the pressure after
the hydraulically actuated tool completes its function, and
mechanically manipulating the drill string to open the expandable
ball seat and allow the ball to pass through.
[0008] US 2009/0084555 discloses an activating mechanism for
controlling the operation of a downhole tool in a drill string and
which is intended to be housed in a portion of the drill string
upstream of the downhole tool, in which the activating mechanism
has a first mode in which it allows through-flow of drilling fluid
to the downhole tool and a second mode in which through-flow of
fluid is blocked. The activating mechanism has a number of
through-flow ports permitting through-flow of drilling fluid in
said first mode of the mechanism and which are capable of being
blocked by launching a number of flow blocking activator balls down
the drill string and which each are of such size and shape that
they can block access to said through-flow ports in order to
activate the mechanism to the second mode and thereby adjust the
downhole tool from one mode of operation to another.
[0009] WO 04/022907 discloses a by-pass tool for incorporation in a
drillstring, and which is adjustable between an inactive mode in
which it allows fluid flow lengthwise of the drillstring during
normal drilling operation, and an active by-pass mode when drilling
is to be interrupted. The tool comprises an outer casing; a sleeve
displaceable axially within the casing, a valve seat associated
with the sleeve and arrange to receive an activating ball, when the
latter is launched from the surface and down the drillstring, said
valve seat being operative to displace the sleeve axially and
thereby initiate adjustment of the tool from the inactive mode to
the active by-pass mode, and by-pass port means in the casing and
arranged to be closed by the sleeve when the tool is in its
inactive mode and to be opened to communicate with the interior of
the drillstring when the tool is in its active mode, said by-pass
port means being arranged above the valve seat so as to allow a
locking ball (when launched from the surface after the valve seat
has received the activating ball) to partially block the port means
and thereby initiate flushing-out of any drillstring fluid debris
above the valve seat via the port means.
[0010] However, an increased performance of downhole tools would
still be desirable.
SUMMARY
[0011] It is therefore desirable to increase drilling fluid flow
rates circulating in the borehole to help clean the borehole.
However, some drill string element such as directional drilling
tools, standard drilling motors, rotary steerable tools,
measurement while drilling tools and log while drilling tools are
highly sensitive to increased flow rates and can even be damaged by
high fluid flow rates.
[0012] Consequently, newer sophisticated drill strings have
restrictions on the amount of volume that can be pumped through the
drill string. Pumping fluid at high rates to clean a well bore and
reduce effective circulating densities (ECDs) can damage
sophisticated and expensive drill strings beyond repair. On the
other hand, pumping at lower rates through such tools can cause the
drill strings to become stuck.
[0013] A second problem associated with drilling extreme wells is
lost circulation of drilling fluid. Lost circulation of drilling
fluid can occur when drilling under pressured formations. These
formations are common in areas that have previously been drilled
many years ago. Often, when drilling in such formations drilling
fluid pumped down the drill string might migrate into low pressure
areas of formation. One way of counteracting this effect is to pump
large particle size drilling fluid, know as lost circulation
material (LCM) into the drill string. LCM has particles of large
size which can plug the formation and prevent loss of drilling
fluid.
[0014] It is an object of the invention to provide a downhole tool
having an increased performance.
[0015] In order to achieve the object defined above, the
subject-matter according to the independent claims is provided.
[0016] According to an exemplary embodiment, a downhole circulation
apparatus arranged to be mounted in a drill string is provided, the
apparatus comprising:
[0017] at least one tubular body portion for mounting in a drill
string, at least one said tubular body portion defining a first
through-flow passage for receiving a flow of drilling fluid through
the drill string;
[0018] first port means formed through at least one said tubular
body portion;
[0019] a first sleeve slidably mounted inside at least one said
tubular body portion, the first sleeve moveable between a closed
position in which said first port means is closed by the first
sleeve and an open position in which said first port means is open
to allow drilling fluid to circulate out of the apparatus;
[0020] first biasing means biasing the first sleeve into the closed
position;
[0021] second port means formed through at least one said tubular
body portion at a location below the first port means when the
apparatus is in use;
[0022] a second sleeve slidably mounted inside at least one said
tubular body portion, the second sleeve moveable between a closed
position in which said second port means is closed by the second
sleeve and an open position in which said second port means is open
to allow drilling fluid to circulate out of the apparatus; and
[0023] second biasing means biasing the second sleeve into the
closed position.
[0024] According to another exemplary embodiment, a downhole
circulation system is provided which comprises:
[0025] a downhole circulation apparatus having the above-mentioned
features;
[0026] a first restriction device; and
[0027] a second restriction device adapted to cooperate with said
first restriction device.
[0028] According to still another exemplary embodiment, a method of
operating a downhole circulation apparatus having the
above-mentioned features is provided, the method comprising:
[0029] a) causing an increase in fluid pressure in the apparatus to
move the first sleeve from the closed to the open position;
[0030] b) causing the first biasing means to move the first sleeve
back to the closed position; and
[0031] c) causing a fluid pressure increase in the apparatus to
move the second sleeve from the closed to the open position.
[0032] According to an exemplary embodiment of the invention, two
or more serially coupled downhole tools are provided each of which
being activatable separately from the other one, and each of which
being selectively bringable in a bypass mode in which a drilling
fluid can be pumped from an interior of the tubular body portion to
an exterior thereof. By serially coupling multiple of such downhole
tools along a drill string, it is possible to selectively introduce
drilling fluid at various defined positions along the bore hole.
Not only the position at which the drilling fluid is introduced in
the bore hole can be selected by activating a respective one of the
normally closed bypass valves, but it is also possible to adjust
the kind of drilling fluid (a bore hole cleaning liquid or loss of
circulation material, for instance) in accordance with specific
requirements at different depths of the drill string.
[0033] Next, further exemplary embodiments of the downhole
circulation apparatus will be explained. However, these embodiments
also apply to the method.
[0034] In an embodiment, the first sleeve and/or the second sleeve
comprises a flow responsive portion responsive to a flow (or fluid
actuation pressure) of drilling fluid through the first
through-flow passage to be thereby movable between the closed
position and the open position depending on the flow of drilling
fluid (i.e. the amount of pressure or flow rate adjustable by an
operator via a fluid pump can be used to switch the respective
sleeve open or closed). The term "flow responsive portion" may
particularly denote a specific component of the sleeve which is
configured so that a fluid flow exceeding a certain threshold value
will actuate the flow responsive portion to thereby move the
respective sleeve from the closed position to the open position
triggered by the fluid flow. Hence, such an embodiment will not
necessarily require balls or other activation structures to be
engaged by a seat of the sleeve or the like, in contrast to this
the fluid pressure of the pumped drilling fluid will be used for
activating the respective downhole tool. For instance, such a flow
responsive portion may be a narrowing section of the respective
sleeve designed to be actuated by a certain fluid flow. However,
the flow responsive portion may alternatively be a portion or part
of the sleeve which is not directly, but only indirectly influenced
by the actual value of the flow. In such an embodiment, application
of fluid actuation pressure to the interior of the tubular
component may act directly on any appropriate internal member such
as a mandrel or the like. Hence, it is also possible that a mandrel
or the like is arranged in the drill string which is movable along
the tool under the influence of fluid pressure. The internal member
may be coupled to the respective sleeve to axially (optionally also
rotatably) displace the respective sleeve when the internal member
is actuated by the fluid. By providing a flow responsive portion,
opening or closing the respective port means may be triggered by a
corresponding adjustment of the pressure conditions or the flow
rate conditions (flowing fluid volume or mass per time interval).
Hence, opening and closing of ports may be performed using pressure
action, particularly increasing and equalizing pump pressure or
pump differential.
[0035] Still referring to the previously described embodiment, the
apparatus may comprise a first clutch member secured to the at
least one said tubular body portion and a second clutch member
axially spaced from the first clutch member and secured to the at
least one said tubular body portion. The respective sleeve may be
axially arranged between the first clutch member and the second
clutch member and may be movable between cooperative engagement
with the first clutch member or the second clutch member by an
indexable latch mechanism. Such a configuration may be denoted as a
clutch mechanism. In such an embodiment, the sleeve is axially,
i.e. in flow direction of the drilling fluid, arranged between the
fixed clutch members which serve as an upper stop element and a
lower stop element for restricting the moving range of the sleeve.
Moreover, also in this embodiment the sleeve may be biased to the
closed position, i.e. abut or be in cooperative engagement with the
upper clutch member in the absence of external forces. However,
triggered by fluid flow (or alternatively triggered by an
activation means such as a ball) the sleeve may be moved from the
cooperative engagement with the upper clutch member to cooperative
engagement with the lower clutch member, or vice versa. For this
purpose, an indexable latch mechanism may be implemented. Such an
index mechanism is disclosed as such for instance in U.S. Pat. No.
6,041,874 which is therefore incorporated by reference.
[0036] It should further be mentioned here that, although the
clutch mechanism is operable in one embodiment without activation
balls or the like (for instance in a manner as disclosed in U.S.
Pat. No. 6,041,874), it is also possible to provide a corresponding
clutch mechanism additionally using activation or deactivation
balls (for instance in a way as disclosed as such in U.S. Pat. No.
7,673,708 which is therefore incorporated by reference).
[0037] In an embodiment, the first sleeve and/or the second sleeve
may comprise engagement means configured for being engaged by or
for receiving a first restriction device. The apparatus may
comprise the first restriction device which comprises a second
through-flow passage (which may be smaller than the first
through-flow passage) and which may be configured so that dropping
the first restriction device into the apparatus causes the first
restriction device to engage the engagement means to cause an
increase in fluid pressure in the apparatus above the first
restriction device which moves the respective sleeve from the
closed to the open position. The apparatus may further comprise a
second restriction device configured so that dropping the second
restriction device into the apparatus causes the second restriction
device to engage the first restriction device and block the second
through-flow passage to cause a fluid pressure increase in the
apparatus above the first and second restriction devices which
moves the first and second restriction devices past the respective
sleeve to cause the respective biasing means to move the respective
sleeve back to the closed position. Such a configuration may be
denoted as a split flow mechanism. The first restriction device in
the described embodiment may be a separate body which can be
dropped into the drill string from outside of a bore hole. The
first restriction device can for instance be a dart or any other
appropriately shaped physical structure having an internal fluid
conduit denoted as the second throughflow passage. The first
restriction device may be configured so that, upon travelling
downwards the drill string, it will rest on the engagement means of
the apparatus due to corresponding shapes, particularly in a manner
that the second through-flow passage is arranged in parallel to the
first through-flow passage. Therefore, when the first restriction
device engages the engagement means, the fluid flow along the axial
direction of the downhole tool will continue, since the drilling
fluid will partially pass through the second through-flow passage
but will at the same time close the first through-flow passage
partially. Thus, while the flow of drilling fluid continues towards
the deepest position of the bore hole (for instance for operating a
downhole motor, or for lubricating or cooling purposes), the
pressure above the first restriction device will at the same time
be increased to open the upper bypass valve so as to enable,
simultaneously to the axial flow, flow of drilling fluid through
the first port means. However, upon dropping the second restriction
device into the bore hole following the first restriction device,
the second restriction device will engage the first restriction
device and will entirely close both through-flow passages, thereby
preventing further flow of drilling fluid towards the deepest
portion of the bore hole and increasing the pressure above the
restriction devices in the engagement means or seat of the
respective sleeve. A result a certain pressure, the restriction
devices will together pass through the engagement means. In one
embodiment, the restriction devices are simply sheared or pressed
through the engagement means. It is also possible that the first
restriction device and/or the engagement means of the sleeve
comprises a deformable material which allows to perform an elastic
deformation so as to enable the respective restriction devices to
pass the engagement means without any deterioration.
[0038] Still referring to the previously described embodiment, the
apparatus may comprise deactivation means (such as one or more
deactivation balls) which may be configured so that dropping the
deactivation means into the apparatus closes the respective port
means to cause a further fluid pressure increase in the apparatus
above the first and second restriction devices which moves the
first and second restriction devices and the deactivation means
past the respective sleeve to cause the respective biasing means to
move the respective sleeve back to the closed position. Hence, to
avoid large pressure values in the drill string (which may be
advantageous for sensitive components in the drill string), one or
more ports of the respective port means may be closed by the
deactivation means prior to forcing the restriction devices through
the engagement means. Optionally, such deactivation means may be
used in conjunction with the above-mentioned restriction devices.
Such deactivation means may, prior to initiating travel of the
restriction devices through the engagement means, close the
respective ports to further increase the pressure on the
restriction devices without an external increase of pump pressure.
The number of deactivation balls of the deactivation means may
correspond to the number of ports of the port means being
controlled by the restriction devices and the deactivation means
(one deactivation ball per port).
[0039] Still referring to the previously described embodiment, the
second restriction device and/or the deactivation means may be
connected to a respective wireline so as to be retrievable from the
apparatus after use to be removed out of the bore hole. When the
described split flow tool relates to the upper sleeve and when the
lower sleeve also works based on activation means and/or
deactivation means dropped into the bore hole, it may be
advantageous to prevent the second restriction device and/or the
deactivation means from travelling downwards. Hence, the second
restriction device and/or the deactivation means may be connected
to a wireline so that it can be pulled out of the bore hole after
having done its job to close the second through-flow passage or the
port means in the upper one of the serial downhole tools.
Optionally, it is also possible that the first restriction device
is connected to a wireline so that also the first restriction
device can be pulled out of the bore hole after use in the upper
downhole valve.
[0040] In an embodiment, the first sleeve and/or the second sleeve
may comprise engagement means configured for receiving activation
means. The apparatus may comprise these activation means which may
be configured so that dropping the activation means into the
apparatus causes the activation means to engage the engagement
means to cause an increase in fluid pressure in the apparatus above
the activation means which moves the respective sleeve from the
closed to the open position. The activation means may further be
configured so that dropping the activation means into the apparatus
causes the first through-flow passage to be closed by the
activation means. The apparatus may comprise deactivation means
configured so that dropping the deactivation means into the
apparatus closes the respective port means to cause a further fluid
pressure increase in the apparatus above the activation means which
moves the activation means and the deactivation means past the
respective sleeve to cause the respective biasing means to move the
respective sleeve back to the closed position. In such an
embodiment, the activation means may be free of a through-hole
passage and will therefore completely close the fluid path towards
the deepest position of the bore hole when the activation means are
engaged by the engagement means. In case of this engagement, the
pressure above the respective sleeve and activation means will
increase, thereby opening the respective port means, since the
biasing force of the respective biasing means will then be overcome
by the fluid pressure increase. Then, the drilling fluid may pass
through the respective ports. In order to deactivate the device,
the activation means (for instance smaller balls in a number
corresponding to the number of ports of the respective port means)
may be dropped into the bore hole so that they will close the
respective ports. Consequently, the pressure will be further
increased above engagement means and activation means, thereby
forcing the activation means and consequently the deactivation
means to pass through the engagement means. This can be performed
by shearing the respective structures (for instance balls) through
the engagement means, or by providing the structures and/or
engagement means of an elastically deformable material which
deforms upon exceeding a certain pressure, thereby forcing the
activation means and the deactivation means through the engagement
means.
[0041] Still referring to the above described embodiment, the
apparatus may optionally comprise locking means configured so that
dropping the locking means into the apparatus (prior to dropping
the deactivation means into the apparatus) locks the respective
port means open until the deactivation means force the locking
means to move out of the port means to an exterior of the tubular
body portion. Such an embodiment may also be denoted as an
automatic locking tool or autolock tool. In this embodiment, the
ports will be locked open by dropping the locking means (for
instance a locking ball of a certain size and of a certain
material) into the drill string. Thus, by clamping the locking
means into the open ports between sleeve and tubular section, the
ports will remain open. Upon dropping the deactivation means into
the bore hole, the locking means will be pressed laterally
outwardly of the drill string so that the locking means will travel
in an annulus between drill string and surrounding bore hole
wall.
[0042] In an embodiment, at least one of the first sleeve and the
second sleeve comprises engagement means configured for receiving
frangible activation means. The apparatus may further comprise the
frangible activation means which may be configured so that dropping
the frangible activation means into the apparatus causes the
frangible activation means to engage the engagement means to cause
an increase in fluid pressure in the apparatus above the frangible
activation means which moves the respective sleeve from the closed
to the open position. The frangible activation means can be
configured so that a further fluid pressure increase in the
apparatus above the frangible activation means destroys (e.g.
breaks) the frangible activation means which (e.g. decomposed into
smaller particles or pieces) thereby moves through the engagement
means to cause a decrease in fluid pressure in the apparatus above
the engagement means which in turn moves the respective sleeve from
the closed to the open position. In certain embodiments of the
apparatus with serially arranged downhole tools, there is the
challenge that the provision of multiple serially coupled downhole
tools located above one another can cause problems with activation
or deactivation means which have been used for an upper downhole
tool and which will later on travel downwardly. Also bringing
activation or deactivation means to a lower downhole tool requires
the means to pass an upper downhole tool first which may be a
mechanical obstacle. In some embodiments, this challenge can be
tackled by an appropriate adjustment of the dimensions of the
various sleeves, engagement means, and
activation/deactivation/restriction means. However, the here
described embodiment provides an alternative solution. In this
embodiment, the activation means are made of a frangible material,
i.e. material which breaks or is destroyed in another way in a
defined manner when certain mechanical load is exceeded. For
instance, when a threshold pressure is exceeded, this will cause
the frangible activation means to be destroyed, for instance to
break into multiple small pieces which can then simply travel
downwardly along the bore hole. For example, such a frangible
activation means may be provided with a predetermined breaking
point. For instance, it may be a hollow structure with a certain
mechanical weakness at one or more predefined positions, so as to
allow to predict the way the frangible activation means will break
upon exceeding of a certain mechanical load, particularly fluid
pressure. Such an embodiment has the advantage over the prior art
of providing means for actuating a downhole tool with an actuating
ball which does not form an undesirable obstruction once the tool
has been actuated.
[0043] In an embodiment, the first sleeve or the second sleeve is
configured with a clutch mechanism as described above, and the
other one of the first sleeve and the second sleeve is configured
with an autolock mechanism as described above. The flow responsive
portion should be dimensioned to be passed by the activation means.
It is possible to arrange the clutch mechanism above or below the
autolock mechanism.
[0044] In an embodiment, the first sleeve or the second sleeve is
configured with a clutch mechanism as described above, and the
other one of the first sleeve and the second sleeve is configured
with a split flow mechanism as described above. The flow responsive
portion shall be dimensioned so that it can be passed by the first
restriction device upon dropping the first restriction device into
the apparatus. The split-flow mechanism may be arranged above or
below the clutch mechanism.
[0045] In order to allow the at least two downhole tools of the
apparatus to be operated and activated separately, the flow
responsive portion may be designed (particularly sized) so that the
restriction device used for activating the split flow tool will
simply pass the clutch mechanism without any interaction.
Therefore, it can be ensured that any of the two downhole tools can
be operated independently from one another, depending on which port
shall be opened (either by adjusting a flow for actuating the flow
responsive portion of the clutch mechanism or by dropping
corresponding activation means into the drill string for operating
the split flow tool).
[0046] In an embodiment, the first sleeve and the second sleeve are
both configured with an autolock mechanism as described above. The
first port means may have one or more ports having a smaller
dimension than one or more ports of the second port means. The
deactivation means for the first sleeve may be dimensioned to pass
through the second port means (or may alternatively be connected to
a wireline or rope in a wireline embodiment so that it can be
retrieved after having operated the upper autolock tool). Also in
this embodiment, independent operability of the two autolock tools
is advantageous. For this purpose, one and the same first
restriction device may be used for both autolock mechanisms
(alternatively, two different and differently sized first
restriction devices may be used for the two autolock mechanisms
which may be connected to a wireline or rope in a wireline
embodiment). After passing (for instance shearing through) the
upper engagement means, the single first restriction device will
simply travel to the lower engagement means and will be engaged
here. As an alternative to passing by shearing, it is also possible
to realize the engagement means and/or the first restriction device
from a deformable material so that the first restriction device is
not in the danger of being deteriorated by the shearing through the
upper engagement means. Moreover, the dimensioning of the second
port means to be larger than the first port means has several
advantages. Firstly, relatively large lower ports may simplify the
supply of lost circulation material to the lower downhole valve.
Secondly, the larger lower ports may be used for removing the
deactivation means of the upper downhole valve out of the drill
string, since they can pass the lower ports due to their larger
size when travelling downwardly. Hence, different deactivation
means (and if required, different locking means), can be used for
the two or more autolock tools arranged above one another.
[0047] In an embodiment, the first sleeve and the second sleeve are
both configured with a frangible body mechanism as described above.
The frangible activation means for the second sleeve may be
dimensioned to pass through the engagement means of the first
sleeve. Even when using frangible activation means, it shall be
ensured that the two mechanisms are adjusted to one another so as
to allow independent operation of the two downhole tools. If the
frangible activation means and the corresponding engagement means
of the upper sleeve have a larger dimension than that the
respective components of the lower sleeve, the upper sleeve can be
activated by the larger frangible activation means. Subsequently,
the frangible activation means is broken into small pieces which
can then also pass the lower engagement means without undesired
activation. Subsequently, dropping a smaller frangible activation
means into the drill string will allow this smaller frangible
activation means to pass the upper engagement means and seat in the
lower, smaller engagement means of the lower sleeve.
[0048] In another embodiment, the first sleeve and the second
sleeve are both configured with a split flow mechanism as described
above. In this embodiment, the first restriction device for the
first sleeve may be the same physical structure as the first
restriction device for the second sleeve. In such a combination of
two above-mentioned split-flow tools, one and the same first
restriction device may be used for both tools, i.e. the two
engagement means may be configured in a similar or identical way.
Also the second restriction device may be the same used for the
upper and the lower split-flow tool. Alternatively, it may be
advantageous to remove the second restriction device from the drill
string after having operated the upper sleeve. Otherwise, the
second restriction device could travel downwards together with the
first restriction device and could continue to block the second
through-flow passage in the lower downhole tool. This can be for
instance prevented by providing the second restriction device with
a wireline to pull it out from the drill string before the first
restriction device travels from the upper engagement means to the
lower one. As an alternative to a wireline, it is possible to
provide the first and second restriction devices with significantly
different densities so that upon travelling downwards in the drill
string, the buoyancy force acting on both restriction devices will
be significantly different so that they will be separated from one
another while travelling downwardly, thereby enabling the split
flow mode in the lower downhole valve as well.
[0049] In an embodiment of the invention, the apparatus comprises
at least one restriction device (or activation device) configured
so that dropping the at least one restriction device into the
apparatus causes the at least one restriction device to engage
first engagement means of the first sleeve to cause an increase in
fluid pressure in the apparatus above the at least one restriction
device which moves the first sleeve from the closed to the open
position, and subsequently releasing the at least one restriction
device from the first engagement means of the first sleeve moves
the at least one restriction device down the apparatus to engage
second engagement means of the second sleeve to cause a fluid
pressure increase in the apparatus above the at least one
restriction device to move the second sleeve from the closed to the
open position. Hence, it is possible to use the same restriction
device for activating both the upper and the lower sleeve. The
releasing may further force the first sleeve to move back from the
open to the closed position.
[0050] As an alternative, an apparatus according to another
preferred embodiment is a combination of a clutch mechanism as
defined above and being operated by fluid flow rather than by one
or more drop devices (such as balls or darts) dropped into the
apparatus, and a drop device operated mechanism (such as a split
flow tool or an autolock tool) operated by one or more devices
dropped into the apparatus. Due to the completely different
activation/deactivation characteristics of such a combination,
independent operation of both mechanisms is ensured increasing
flexibility for a user.
[0051] In an embodiment, the apparatus comprises third port means
formed through at least one said tubular body portion at a location
below the second port means when the apparatus is in use, a third
sleeve slidably mounted inside at least one said tubular body
portion, the third sleeve moveable between a closed position in
which said third port means is closed by the third sleeve and an
open position in which said third port means is open to allow
drilling fluid to circulate out of the apparatus, and third biasing
means biasing the third sleeve into the closed position.
Accordingly, it is possible to also combine three or more downhole
tools serially above one another. The various combined downhole
tools may be of the same type (for instance all of them may be
autolock tools or all of them may be clutch mechanisms, or
different types can be combined, for instance autolock tools and/or
split-flow tools and/or clutch mechanisms).
[0052] In an embodiment, the first sleeve and the second sleeve of
the apparatus may be operable independently from one another, i.e.
each of the bypass paths formed by the drill string and the port
means may be operated (opened or closed) independently from the
other one.
[0053] A preferred embodiment of the present invention seeks to
overcome the above disadvantages of the prior art, partially or
entirely.
[0054] According to an aspect of the present invention, there is
provided a downhole circulation apparatus arranged to be mounted in
a drill string, the apparatus comprising:
[0055] at least one tubular body portion for mounting in a drill
string, at least one said tubular body portion defining a first
through-flow passage for receiving a flow of drilling fluid through
the drill string;
[0056] first port means formed through at least one said tubular
body portion;
[0057] a first sleeve slidably mounted inside at least one said
tubular body portion, the first sleeve moveable between a closed
position in which said first port means is closed by the first
sleeve and an open position in which said first port means is open
to allow drilling fluid to circulate out of the apparatus;
[0058] first biasing means biasing the first sleeve into the closed
position;
[0059] second port means formed through at least one said tubular
body portion at a location below the first port means when the
apparatus is in use;
[0060] a second sleeve slidably mounted inside at least one said
tubular body portion, the second sleeve moveable between a closed
position in which said second port means is closed by the second
sleeve and an open position in which said second port means is open
to allow drilling fluid to circulate out of the apparatus; and
[0061] second biasing means biasing the second sleeve into the
closed position;
[0062] wherein the apparatus is arranged such that:
[0063] a) dropping a first restriction device comprising a second
through-flow passage into the apparatus causes the first
restriction device to engage first engagement means of said first
sleeve to cause an increase in fluid pressure in the apparatus
above the first restriction device which moves the first sleeve
from the closed to the open position;
[0064] b) dropping a second restriction device into the apparatus
after the first restriction device has been dropped causes the
second restriction device to engage the first restriction device
and block the second through-flow passage to cause a fluid pressure
increase in the apparatus above the first and second restriction
devices which moves the first and second restriction devices past
the first sleeve to cause the first biasing means to move the first
sleeve back to the closed position; and
[0065] c) wherein the first and second restriction devices move
down the apparatus to engage second engagement means of said second
sleeve to cause a fluid pressure increase in the apparatus above
the first and second restriction devices to move the second sleeve
from the closed to the open position.
[0066] By providing a downhole circulation tool comprising first
and second port means and sleeves that are operable in response to
the dropping of first and second restriction devices as defined
above, this provides the advantage of a downhole circulation
apparatus that can be used to both increase flow rates of drilling
fluid in the tool for use in cleaning well bores and also can be
used to bypass large particle size drilling fluid (LCM) in order to
plug formations and prevent lost circulation.
[0067] Dropping a first restriction device comprising a second
through-flow passage into the apparatus enables a split flow of
drilling fluid to be achieved. Some of the flow continues through
the second through-flow passage of the dart and some of the
drilling fluid is bypassed out of the first port means to travel
back up the well bore and clean the bore. This enables operators on
the surface to increase fluid flow without damaging the drill
string below the split at the first port means because the
additional flow will exit the first port means.
[0068] Alternatively, if large particle size drilling fluid is
required to be used during the same drilling operation to plug
under-pressured formations and prevent lost circulation, the second
restriction device can be dropped. The second restriction device is
adapted to block the second through-flow passage of the first
restriction device to prevent flow of drilling fluid in the drill
string below the combination of the first and second restriction
devices. This protects sensitive components of the drill string and
opens the second port means such that LCM can be circulated.
Consequently, the apparatus enables two important functions to be
achieved by the same drill string.
[0069] This also provides the advantage that the apparatus can be
used to control the speed of standard drilling motors. Standard
drilling motors function by means of a positive displacement rotor
and stator in which the speed (RPM) is directly controlled by the
volume of fluid pumped through the motor. Splitting the fluid flow
in the apparatus therefore could be used to change the flow rate
through the motor.
[0070] Such an arrangement allows to combine split flow systems for
hole cleaning applications with circulating systems to pump high
concentrations of lost circulation material (LCM). These challenges
are unique and are unrelated to each other. It is believed to be
impossible or at least very difficult to provide one circulating
tool to deal with both problems as split flow/flow booster systems
may require small tungsten carbide nozzles in the tool for certain
applications. These smaller nozzles will control the bypassed flow
out of the tool and need to maintain high pressure drops through
the nozzles to maintain high operating pressures in the drill
string. Conversely, a multiple function autolock bypass system may
utilize ports with a TFA (total flow area) as large as possible to
allow for any pumpable size or concentration of LCM to be easily
pumped through the ports in the tool. These large ports also help
with the filling of the pipe and draining of the pipe during drill
string removal from the well or tripping. These large ports will
also help when reverse circulating is required. Embodiments for
such a tandem device as disclosed herein are designed to deal with
these two common problems with a system that implements two or more
systems and optionally one ball catcher system run below. With a
split flow dart system/ball cluster run above and a multiple
activation autolock bypass system run below, operators will finally
have the ability to deal with both these problems with tools that
work in tandem in the same drill string. The split flow tool may be
run above the autolock tool. To activate the split flow a split
flow dart is pumped into the split flow tool when it lands it
activates the split flow. With this system activated, drill and
hole cleaning can be enhanced. If lost circulation is encountered
then the following procedure will be performed. Drop one of the
split flow deactivation balls. When this deactivation ball reaches
the split flow dart it will plug the dart. This will cause a
significant reduction in the TFA and allow the system to pressure
up to the point at which the split flow dart will shear through the
seat in the split flow tool. When the dart leaves the split flow
tool, the sleeve in the split flow tool will close. The split flow
dart and deactivation ball will land in the autolock tool below
opening the autolock tool. With the split flow dart and
deactivation ball landed on the autolock tool the ports on the
autolock tool will open. With the ports on the autolock tool open,
the displacement of LCM can start. Because the dart has the split
flow deactivation ball in place plugging the internal diameter of
the dart, all the LCM will be displaced out of the ports into the
open hole. Because the TFA on the ports in the tool is so large
this dart and ball will stay in place as long as it is required. To
pressure up and close the system the other two split flow
deactivation balls are dropped and when they reach the autolock
tool they will plug the circulating ports allowing the system to
pressure up and deactivate the autolock tool. The dart and balls
will be retained in the ball catcher. Both of these tools will work
in the same drill string and can be activated independently.
[0071] In a preferred embodiment, the second sleeve is moveable
back to the closed position by said second biasing means in
response to dropping deactivation means into the apparatus to block
said second port means and cause a fluid pressure increase in the
apparatus to move the first and second restriction devices past the
second sleeve.
[0072] This provides the advantage that dropping deactivation means
into the apparatus closes the second port means and cycles the
apparatus back to the starting condition. The cycle can be started
again by dropping first restriction means.
[0073] The deactivation means may comprise at least one
deactivation ball.
[0074] The apparatus of any of the embodiments disclosed herein
which includes at least one activation means/deactivation
means/restriction device (such as balls, darts or the like) may
further comprise a restriction device catcher located below said
second sleeve when the apparatus is in use.
[0075] In a preferred embodiment, said first port means comprises a
plurality of first nozzles arranged to direct drilling fluid into a
drilled borehole in a direction opposite to the direction of
advancement of the apparatus.
[0076] This provides the advantage of minimising hole erosion and
increasing the cleaning effect of the bypassed fluid.
[0077] Said plurality of first nozzles may be formed from tungsten
carbide.
[0078] This provides the advantage of hard wearing nozzles which
consistently pass a predetermined volume of fluid.
[0079] In a preferred embodiment, the second port means comprises a
plurality of second nozzles, wherein each said second nozzle has a
diameter greater than the diameter of each of said first
nozzles.
[0080] This provides the advantage of nozzles that are suited to
bypassing large particle size drilling fluid (LCM).
[0081] The first restriction device may be arranged to allow
approximately 70% of the fluid flow in the apparatus to pass
through the second through-flow passage when engaged with the first
engagement means, such that approximately 30% of the fluid flow in
the apparatus is directed through said first port means.
[0082] The apparatus may be formed from an assembly of a plurality
of drill string elements comprising:
[0083] a first tool element comprising a first tubular body
portion, first port means formed through said first tubular body
portion and a first sleeve slidably mounted inside said first
tubular body portion;
[0084] a second tool element arranged below said first tool element
when the apparatus is in use, the second tool element comprising a
second tubular body portion, second port means formed through said
second tubular body portion and a second sleeve slidably mounted
inside said second tubular body portion; and at least one drill
pipe element disposed between and interconnecting said first tool
element with said second tool element.
[0085] The apparatus may further comprise a plurality of drill pipe
elements disposed between and interconnecting said first tool
element with said second tool element.
[0086] This provides the advantage of preventing the first and
second restriction devices from blowing past the second engagement
means of the second sleeve which would cause the second sleeve not
to activate. When the first and second restriction devices blow
past the first sleeve, they have a considerable velocity and
inertia which is reduced by having several lengths of drill pipe
(extending to 60 feet for example) above the second sleeve.
[0087] In a preferred embodiment, said first restriction device is
a dart comprising:
[0088] a hollow body portion defining said second through-flow
passage;
[0089] at least one deformable portion arranged to engage the first
and second engagement means of the respective first and second
sleeves; and
[0090] a ball seat disposed in the second through-flow passage, the
ball seat arranged to receive a ball to block said second
through-flow passage.
[0091] Said dart may further comprise retention means disposed
adjacent said ball seat, the retention means arranged to prevent a
ball located in the ball seat from moving out of the ball seat in a
first direction, but permit a ball located in the ball seat to move
past the ball seat in a second direction.
[0092] This provides the advantage of preventing a ball located in
the ball seat from moving back up the drill string, i.e. towards
the surface. If this happened, the ball could become lodged in one
of the circulation ports which could cause a drill string
failure.
[0093] Said retention means may comprise a plurality of teeth
disposed on the hollow body portion.
[0094] According to another aspect of the present invention, there
is provided a downhole circulation system comprising:
[0095] a downhole circulation apparatus as defined above;
[0096] a first restriction device comprising a second through-flow
passage; and
[0097] a second restriction device adapted to engage said first
restriction device and block the second through-flow passage.
[0098] According to a further aspect of the present invention,
there is provided a method of operating a downhole circulation
apparatus as defined above, the method comprising the steps of:
[0099] a) dropping a first restriction device comprising a second
through-flow passage into the apparatus to cause the first
restriction device to engage first engagement means of said first
sleeve and cause an increase in fluid pressure in the apparatus
above the first restriction device to move the first sleeve from
the closed to the open position;
[0100] b) dropping a second restriction device into the apparatus
after the first restriction device has been dropped to cause the
second restriction device to engage the first restriction device
and block the second through-flow passage to cause a fluid pressure
increase in the apparatus above the first and second restriction
devices which moves the first and second restriction devices past
the first sleeve and causes the first biasing means to move the
first sleeve back to the closed position; and
[0101] c) wherein the first and second restriction devices move
down the apparatus to engage second engagement means of said second
sleeve to cause a fluid pressure increase in the apparatus above
the first and second restriction devices to move the second sleeve
from the closed to the open position.
[0102] This provides the advantage of a method of operating a
downhole circulation apparatus that can be used to both increase
flow rates of drilling fluid in the tool for use in cleaning well
bores and can also be used to bypass large particle size drilling
fluid (LCM) in order to plug formations and prevent lost
circulation.
[0103] Dropping a first restriction device comprising a second
through-flow passage into the apparatus enables a split flow of
drilling fluid to be achieved. Some of the flow continues through
the second through-flow passage of the dart and some of the
drilling fluid is bypassed out of the first port means to travel
back up the well bore and clean the bore. This enables operators on
the surface to increase fluid flow without damaging the drill
string below the split at the first port means because the
additional flow will exit the first port means.
[0104] Alternatively, if large particle size drilling fluid is
required to be used during the same drilling operation to plug
under-pressured formations and prevent lost circulation, the second
restriction device can be dropped. The second restriction device is
adapted to block the second through-flow passage of the first
restriction device to prevent flow of drilling fluid in the drill
string below the combination of the first and second restriction
devices. This protects sensitive components of the drill string and
opens the second port means such that LCM can be circulated.
Consequently, the apparatus enables two important functions to be
achieved by the same drill string.
[0105] The method may further comprise dropping at least one
deactivation means into the apparatus to block said second port
means and cause a fluid pressure increase in the apparatus to move
the first and second restriction devices past the second sleeve and
cause the second biasing means to move the second sleeve back to
the closed position.
BRIEF DESCRIPTION OF THE DRAWINGS
[0106] Preferred embodiments of the present invention will now be
described, by way of example only, and not in any limitative sense,
with reference to the accompanying drawings in which:
[0107] FIGS. 1 to 11 are a series of cross-sectional drawings of a
downhole circulation apparatus embodying the present invention
showing progressive steps from dropping a first restriction device
in FIG. 1 to the end of the cycling of the tool in FIG. 11;
[0108] FIG. 12 is a cross-sectional close up view of the first and
second restriction devices;
[0109] FIG. 13a is a cross sectional view of a second embodiment of
the first restriction device comprising retention means;
[0110] FIG. 13b is a close up of the retention means of FIG. 13a
engaging a second restriction device;
[0111] FIG. 14 is a cross-sectional drawing of a downhole
circulation apparatus embodying the present invention showing a
combination of a clutch mechanism downhole tool above and an
autolock mechanism downhole tool below;
[0112] FIG. 15 is a cross-sectional drawing of a downhole
circulation apparatus embodying the present invention showing a
combination of an autolock mechanism downhole tool above and a
clutch mechanism downhole tool below;
[0113] FIG. 16 is a cross-sectional drawing of a downhole
circulation apparatus embodying the present invention showing a
combination of a split flow mechanism downhole tool above and a
clutch mechanism downhole tool below;
[0114] FIG. 17 is a cross-sectional drawing of a downhole
circulation apparatus embodying the present invention showing a
combination of an autolock mechanism downhole tool above and
another autolock mechanism downhole tool below;
[0115] FIG. 18 is a cross-sectional drawing of a downhole
circulation apparatus embodying the present invention showing a
combination of a frangible activation mechanism downhole tool above
and another frangible activation mechanism downhole tool below;
[0116] FIG. 19 is a cross-sectional drawing of a downhole
circulation apparatus embodying the present invention showing a
combination of a split flow mechanism downhole tool above and
another split flow mechanism downhole tool below;
[0117] FIG. 20 is a cross-sectional drawing of a downhole
circulation apparatus embodying the present invention showing a
combination of three serially arranged autolock downhole tools;
[0118] FIG. 21 to FIG. 26 show cross-sectional drawings of a
downhole circulation apparatus embodying the present invention
showing a combination of a ball operated downhole tool above and a
clutch mechanism downhole tool below.
[0119] The illustration in the drawings is schematic. In different
drawings, similar or identical elements are provided with the same
reference numerals.
DETAILED DESCRIPTION
[0120] Referring to FIG. 1, a downhole circulation apparatus 2 is
arranged to be mounted in a drill string as shown in FIG. 1. The
downhole circulation apparatus 2 comprises at least one tubular
body portion 4 defining a first through-flow passage 6 through
which drilling fluid can pass along the drill string.
[0121] First port means 8 is formed through the tubular body 4. The
first port means is a bypass port and may comprise a plurality of
nozzles formed from tungsten carbide. A first sleeve 10 is slidably
mounted in the tubular body portion 4 and is biased into a position
in which the first port means 8 is closed by a biasing means such
as a spring 12. The first sleeve 10 is disposed in a first drill
string element which is connected to several joints of drill pipe
16 at a lower end 14. The interconnection of drill string elements
will be familiar to person skilled in the art.
[0122] Second port means 18 is formed through the tubular body
portion 4 at a location below the first port means 8 in the drill
string. The second port means 18 may comprise a plurality of second
nozzles, wherein each of the second nozzles has a diameter greater
than the diameter of each of the first nozzles of the first port
means 8. Larger nozzles enable large particle size drilling fluid
such as LCM to be bypassed. A second sleeve 20 is slidably mounted
inside the tubular body portion 4 and is arranged to close second
port means 18 in the condition shown in FIG. 1. Second sleeve 20
comprises second engagement means 21 such as a ball or dart seat. A
restriction device catcher, such as a ball and dart catcher
assembly 24 is provided below the first and second sleeves.
[0123] Although the embodiment shown shows the first and second
sleeves located in different drill string elements, they could
alternatively be mounted in a single drill string element. Also all
further embodiments shown below can have the different sleeves in
different drill strings, or may be mounted in a single drill string
element.
[0124] Referring to FIG. 12, a first restriction device 30
comprises a second through flow passage 32. The first restriction
device 30 may be a dart formed from steel. Second through flow
passage 32 is narrower than first flow through passage 6 and
therefore will cause a fluid pressure increase above dart 30. A
restricted through-flow passage member 34 may also be mounted in
the deformable dart 30, although the restricted through-flow
passage 34 could be integrally formed in the deformable dart 30. By
providing interchangeable restricted through-flow passage members
34, the dart can be changed to be used with different tools and
applications.
[0125] A deformable portion 36 forms a widened portion of the
deformable dart 34. The deformable portion 36 is arranged to abut
against first engagement means 11 or second engagement means 21 of
the downhole circulation apparatus 2. When the portion 36 contacts
seat 11, the increased pressure resulting from fluid passing
through restriction 34 pushes on the dart causing the first sleeve
10 to move downwardly against spring 12.
[0126] A second restriction device 38 may comprise a ball or other
member suitable for blocking second through flow passage 32. Ball
38 may be formed from steel or plastics material and is arranged to
seat in an opening seat 40 of the dart 30. The ball blocks the
second through-flow passage 32 preventing drilling fluid from
passing through dart 30 and therefore to the part of the drill
string below the dart and ball combination 30, 38. If sufficient
force is applied to the dart and ball combination 30 and 38,
deformable portion 36 deforms enabling flushing of the dart and
ball past the second engagement means 21.
[0127] Referring to FIGS. 13a and 13b, a second embodiment of first
restriction device 30 comprises retention means for retaining the
ball in seat 40. The retention means may comprise for example a
plurality of teeth 41 that grip the ball 38 and prevent it from
moving back along the drill string towards the surface, but permit
the ball 38 to move downwardly in the drill string. Another example
of a retention means that could be used is a split ring having a
taper.
[0128] The operation of the downhole circulation tool 2 will now be
described by referring to FIGS. 1 to 11 in sequence describing the
steps that comprise a full cycle of the apparatus 2.
[0129] Referring to FIG. 1, dart 30 (FIG. 12) is dropped into the
drill string containing the apparatus 2. It will be appreciated by
persons skilled in the art that dart 30 is dropped from the surface
and there may be several lengths of drill string above the portion
shown in FIG. 1 such that the dart 30 travels along with drilling
fluid down to the location of the portion shown in Figure.
[0130] Referring to FIG. 2, dart 30 engages first seat 11 and as a
result of a fluid pressure increase in the drill string caused by
fluid passing through second through-flow passage 32 (FIGS. 12 and
13), the first sleeve 10 is pushed downwardly against first spring
12 opening the first bypass port means 8. Consequently, drilling
fluid 50 can pass through first port means 8 and out of the tool.
In the embodiment shown in FIG. 2, the nozzles forming first port
means 8 are arranged to direct fluid upwardly away from the
direction of advancement of the drill string to minimise hole
erosion and help with hole cleaning. In this example, the dart is
arranged to pass 70% of the fluid down the drill string such that
30% of the fluid 50 is bypassed.
[0131] When first port means 8 opens, the drill string operator at
the surface may see a decrease in pump pressure. The operator can
then increase the volume of fluid pumped without damaging the drill
string.
[0132] Referring to FIG. 3, in order to close first port means 8 a
second restriction device such as ball 38 is dropped into the drill
string.
[0133] Referring to FIG. 4, the ball 38 seats in dart 30 as shown
in FIG. 12. Ball 30 may also be retained by teeth 41 (FIG. 13).
This causes a blockage in the drill string and prevents drilling
fluid from passing the dart and ball 30, 38. This causes a large
pressure increase above the ball 38.
[0134] Referring to FIG. 5, this large pressure increase causes the
first and second restriction devices to move past the first sleeve.
For example, the deformable portion 36 of dart 30 deforms and the
ball and dart 30, 38 blow past the first seat 11. The dart and ball
30, 38 are therefore pushed down the drill string along with
drilling fluid.
[0135] Referring to FIG. 6, the ball and dart 30, 38 come into
engagement with second seat 21. Second sleeve 20 is therefore moved
downwardly against spring 22 to cause the second port means 18 to
be opened. Large particle size drilling fluid 60 can be circulated
from second port means 18, which may comprise a plurality of large
nozzles, in order to plug a formation and prevent fluid circulation
loss.
[0136] Referring to FIG. 7, the apparatus comprises an auto-lock
feature which can be used to clean the interior of the drill string
and allow the drill string to be drained and filled as required. A
plastic auto-lock ball 42 having a diameter greater than the
diameter of one of the nozzles of the second port means 18 is
dropped into the string and seats in one of the nozzles. This
blocks the nozzle and only enables drilling fluid 60 to be
circulated out of the other nozzle. In the embodiment shown in the
drawings, there are two nozzles forming second port means 18,
although it will be apparent to person skilled in the art that one
or more nozzles can be employed.
[0137] Referring to FIG. 8, in order to deactivate the apparatus,
deactivation means such as at least one steel deactivation ball 44
is dropped. If only one nozzle is present in second port means 18,
only a single deactivation ball 44 is required. However, in the
embodiment shown in the drawings there are two ports forming second
port means 18 and therefore two deactivation balls 44 are required
to be dropped into the drill string.
[0138] Referring to FIG. 9, if the plastic auto-lock ball 42 is
present, deactivation balls 44 seat in the nozzles 18. Also, the
drill string is blocked by the ball and dart combination 30, 38.
This causes a large increase in pressure and blows auto-lock ball
42 out of the nozzle. The large increase in pressure also causes
deformable portion 36 of dart 30 to shear and be blown past second
seat 21.
[0139] Referring to FIG. 10, the ball and dart 30, 38 and the two
steel deactivation balls 44 fall through the drill string and are
caught in ball catcher 24 as shown in FIG. 11. This completes a
cycle of the apparatus. The cycle can be started again from the
step of FIG. 1 and the cycle can be repeated until the ball and
dart catcher 24 is full.
[0140] Furthermore, several alternatives to the described
embodiments of FIG. 1 to FIG. 13 are possible. For example, it is
possible to omit the plastic auto-lock ball 42. In such an
embodiment, the tool will function without a locking feature which
reduces the amount of required balls to be dropped into the drill
string.
[0141] In a further alternative, it is possible to provide two
additional balls for the upper split flow mechanism, in addition to
the restriction devices 30, 38. These two additional balls can have
a similar function as steel deactivation balls 44 used for
operating the lower mechanism. When such additional balls are used
for the upper split-flow mechanism, it is possible to close the
upper ports 8 in an operation mode between FIG. 4 and FIG. 5,
thereby allowing to further increase the pressure above the
restriction devices 38, 30 before forcing them through the
engagement means 11 of the upper sleeve 10.
[0142] FIG. 14 shows a downhole circulation apparatus 1400
according to another exemplary embodiment of the invention.
[0143] As in the embodiment of FIG. 1 to FIG. 11, also the downhole
circulation apparatus 1400 is arranged to be mounted in a drill
string. A tubular body portion 4 is foreseen for mounting in a
drill string. A through-flow passage 6 is defined as a lumen within
the tubular body portion 4 for receiving a flow of drilling fluid
through the drill string. First ports 8 in the form of nozzles are
formed through the tubular body portion 4. A first sleeve 10 is
mounted inside the tubular body portion 4 to be movable between a
closed position (shown in FIG. 14) in which the port means 8 is
closed due to intended misalignment with ports 74 of the first
sleeve 10 and an open position in which the port means 8 is open
due to alignment with ports 74 (not shown) to allow drilling fluid
being conducted from an upper end 70 of the through-flow passage 6
to circulate out of the apparatus via the ports 74 and the port
means 8. An annulus 76 is formed between an outer surface of the
tubular body portion 4 and a wall 72 of the bore hole which is
surrounded by formation material. In other words, in the
configuration shown in FIG. 14, the port means 8 of the tubular
body portion 4 is not in alignment with the ports 74 of the sleeve
10, thereby preventing fluid communication between an interior of
the tubular body 4, the ports 74, the ports means 8 and annulus 76.
However, upon a certain downward movement of the sleeve 10, it is
possible to bring the ports 8, 74 in alignment, thereby selectively
enabling fluid communication between through-flow passage 70, ports
74, 8 and the annulus 76.
[0144] Biasing means (not shown in FIG. 14) such as a spring
(compare reference numeral 80) or the like is provided which biases
the sleeve 10 in the closed position as shown in FIG. 14. Such
biasing means can be configured for instance in a similar manner as
reference numeral 18 in FIG. 1A of WO 01/06086.
[0145] Additionally, a second port means 18 is formed through the
tubular body 4 at a location below the first port means 8.
Correspondingly, a second sleeve 20 is slidably mounted inside the
tubular body portion 4, being movable between a closed position
(shown in FIG. 14) in which the second port means 18 are closed by
the second sleeve 20 (more precisely due to intended misalignment
with ports 78 of the second sleeve 20) and an open position (not
shown) in which the second port means 18 is open due to alignment
with ports 78 to allow drilling fluid to circulate out of the
apparatus 1400 via the lower port means 18 and ports 78. As can be
taken from FIG. 14, the lower port means 18 is not in alignment
with ports 78 of the second sleeve 20. However, if the second
sleeve 20 is moved downwardly, the ports 18, 78 can be brought in
alignment, thereby allowing for fluid communication between the
first through-flow passage 6, the ports 78, 18 and the annulus 76.
Second biasing means in the form of a spring 80 is provided which
biases the second sleeve 20 towards the closed position.
[0146] In the embodiment of FIG. 14, the upper downhole tool of
apparatus 1400 is realized as a clutch mechanism, as will be
described in the following in more detail. The first sleeve 10
comprises a flow responsive portion 82 in the form of a narrowing
section of an annular shape. The flow responsive portion 82 is
arranged to interact with drilling fluid conducted by a pump (not
shown) along an axial direction 84 of the apparatus 1400. When a
fluid pressure of the drilling fluid which is conducted along the
axial direction 84 (for instance in order to drive a downhole motor
(not shown), lubricate downhole components, etc.) exceeds a
predefined threshold value, the force acting on the flow responsive
portion 82 will be larger than the biasing force of the first
biasing means (not shown). Hence, this force will move sleeve 10
downwardly to bring the ports 8, 74 in alignment, thereby enabling
bypassing of fluid from the flow through-passage 6 towards the
annulus 76. For example, drilling fluid for bore hole cleaning can
be conducted into the annulus 76. Hence, by adjusting the flow rate
or the liquid pressure, it is possible to operate the upper clutch
mechanism.
[0147] In addition to the already described features, the clutch
mechanism furthermore comprises a first clutch member 86 secured to
the tubular body 4 in a fixed manner. Moreover, a second clutch
member 88 is axially spaced with regard to the first clutch member
86 but is also rigidly fixed or secured to the tubular body portion
4. The sleeve 10 is axially arranged or sandwiched between the
first clutch member 86 and the second clutch member 88 and can be
mounted for axial and/or rotational displacement between the upper
abutment position shown in FIG. 14 and the lower abutment position
in which the lower end of the sleeve 10 abuts against the second
clutch member 88. Furthermore, when the sleeve 10 abuts against one
of the clutch members 86, 88, a cooperative engagement between the
sleeve 10 and the respective one of the clutch members 86, 88
occurs which can be realized by an indexable latch mechanism (not
shown in detail). Therefore, the sleeve 10 will interlock with the
corresponding latching mechanism, thereby locking the sleeve 10
selectively in the upper or the lower position. The biasing means
will always have the tendency to drive back the sleeve 10 into the
upper position in the absence of external forces. The skilled
person is aware of corresponding latching mechanisms for latching a
clutch mechanism in the upper or lower position, compare for
instance U.S. Pat. No. 6,041,874 or WO 01/06086.
[0148] While the clutch mechanism in the upper portion of FIG. 14
will be operated by fluid pressure, the autolock mechanism located
in the lower portion of the apparatus 1400 will be operated by
dropping a number of balls, as will be described in the following
in more detail.
[0149] For this purpose, the second lower sleeve 20 comprises the
engagement means 21 in the form of a seat which is shaped so as to
receive a spherical activation ball 90. This activation ball 90
which may be made of steel can be dropped into the tubular body 4
from a top of the bore hole. Since a lateral extension of the
activation ball 90 is smaller than a lateral extension of the
narrowest portion of the flow responsive portion 82, the activation
ball 90 will travel downwardly along the axial direction 84 and
will be seated in the seat of the engagement means 21 in a position
indicated with 1. This will increase the fluid pressure above the
activation means 90 in the engagement means 21 which moves the
second sleeve 20 from the closed position (FIG. 14) to the open
position (not shown) in which the ports 78, 18 are in alignment. In
this position, it is possible to bypass a bore hole fluid such as a
cleaning fluid or loss circulation material through the ports 78,
18 into the annulus 76.
[0150] In order to lock the apparatus 1400 in the open state of
ports 18, 78, a plastic locking ball 42 is dropped into the bore
hole and will clamp between the ports 18, 78, as indicated
schematically with II in FIG. 14. In other words, locking ball 42
will clamp between ports 18, 78 and will therefore lock the lower
bypass valve in the open state.
[0151] In order to subsequently close the locked lower bypassing
mechanism, steel balls 44 are dropped into the apparatus 1400. They
will accommodate in the ports 78, as indicated with III and IV.
Furthermore, the deactivation ball 44 placed at the position IV
will also press locking ball 42 outwardly so that the latter will
move into the annulus 76. Closing the ports 78 by the deactivation
balls 44 will further increase the pressure above engagement means
21 which is already in engagement with activation means 90, thereby
pressing activation means 90 and deactivation means 44 through the
seat of engagement means 21. Hence, the balls 90, 44 will be stored
in a ball catcher assembly (compare reference numeral 24 in FIG. 1
to FIG. 11) not shown in FIG. 14 and the following figures.
[0152] FIG. 15 shows an apparatus 1500 according to another
exemplary embodiment of the invention. Apparatus 1500 differs from
the apparatus 1400 only in that the upper downhole tool is an
autolock mechanism and the lower downhole tool is a clutch
mechanism, so that the downhole tools of FIG. 14 are
interexchanged.
[0153] Apparatus 1600 according to another exemplary embodiment and
shown in FIG. 16 differs from the apparatus 1500 in that the upper
downhole tool is not realized as an autolock tool (as in FIG. 15),
but as a split-flow tool (as in FIG. 1). In other words, the upper
downhole tool of FIG. 16 can be realized in a similar manner as the
upper downhole tool described above referring to FIG. 1 to FIG.
13.
[0154] In FIG. 16, the upper sleeve 10 comprises engagement means
11 configured for receiving a first restriction device 30. The
first restriction device 30 has a second through-flow passage 32
and is configured so that dropping the first restriction device 30
into the apparatus 1600 causes the first restriction device 30 to
engage the engagement means 11 to cause an increase in fluid
pressure above the first restriction device 30 which moves the
first sleeve 10 from the closed position (compare FIG. 16) to the
open position (not shown). In the open position, ports 74, 8 are in
alignment, whereas they are not in alignment in the operation mode
shown in FIG. 16. When the first restriction device 30 (which can
be realized as a dart or in the way shown in FIG. 12 or FIG. 13)
engages engagement means 11 to bring ports 74, 8 in alignment,
there is simultaneously a fluid flow along first through-flow
passage 70 as well as a bypass flow through aligned ports 74, 8.
Dropping subsequently a second restriction device 38, realized as a
ball in FIG. 16, into the apparatus 1600 causes the second
restriction device 38 to engage the first restriction device 30,
thereby blocking the second through-flow passage 32. This causes a
fluid pressure increase in the apparatus 1600 above the restriction
devices 30, 38. This moves both restriction devices 30, 38 past the
upper sleeve 10 to cause biasing means 80 of the split flow
mechanism to move the first sleeve 10 back to the closed position
of FIG. 16. This can be performed in a similar manner as described
above referring to FIG. 1 to FIG. 5.
[0155] However, it is optionally possible to use deactivation means
44 in a similar manner as described above referring to FIG. 14 and
FIG. 15 for an
[0156] autolock mechanism: The fluid pressure above the restriction
devices 30, 38 in engagement means 11 can be further increased by
dropping deactivation means 44 into the apparatus 1600 so that they
will block ports 74, thereby forcing members 30, 38, 44, 44 to pass
through engagement means 11 as well as through the below clutch
mechanism in a downward direction to be caught in a ball catching
device 24 (not shown in FIG. 16).
[0157] Since the diameter of the flow responsive portion 82 below
is, even at the narrowest position, wider than a lateral extension
of first restriction device 30, downward travel of members 30, 38,
44, 44 will not influence the lower downhole tool in FIG. 16.
[0158] The lower downhole tool in FIG. 16, a clutch mechanism, can
again be operated in a similar way as described referring to FIG.
14 and FIG. 15.
[0159] It should also be said that the clutch mechanism and the
split-flow mechanism of FIG. 16 can be arranged vice versa, i.e.
the clutch mechanism above the split-flow mechanism.
[0160] In the following, referring to FIG. 17, an apparatus 1700
according to another exemplary embodiment of the invention will be
described which is basically a combination of two autolock tools of
the type shown in the upper portion of FIG. 15. In the shown
embodiment, both autolock devices are configured identically with
the exception that the lower autolock tool has larger ports 74' of
the sleeve 10 as compared to the ports 74 of the upper sleeve 10.
Upper port means have smaller ports 8 than ports 18 of lower port
means of the tube 4. For operation, steel ball 90 functioning as an
actuating means is dropped into the drill string to thereby be
engaged in the engagement means 11 of the upper downhole tool. This
increases the fluid pressure above the arrangement 11, 90, thereby
opening the above bypass valve so that ports 74, 8 are aligned and
drilling fluid can be bypassed from through-flow passage 70 via
ports 74, 8 into the surrounding annulus. For locking the upper
bypass valve open, optional but advantageous locking ball 42 may be
dropped into the drill string which will clamp between ports 8, 74.
Subsequently, deactivating means in the form of two smaller (as
compared to ball 90) balls 44 are dropped into the drill string and
will close the ports 74. This will increase the pressure above
arrangement 90, 11 thereby forcing activating ball 90 together with
deactivating balls 44 in a downward direction. Locking ball 42 will
move out of the drill string under the influence of one of the
deactivating balls 44.
[0161] When arriving at the lower autolock tool of FIG. 17,
activation ball 90 will be engaged by engagement means 11 of the
lower downhole valve. Since the ports 74', 18 are larger than the
corresponding ports 74, 8, deactivating balls 44 may leave the
apparatus 1700 towards the annulus or may remain on engagement
means 11. Hence, the system is then in an operation mode in which
the lower bypass valve is open due to the increased pressure
resulting from the activating means 90 being engaged in the
engagement means 11 of the lower downhole valve. This allows to
bypass fluid via the fluid communication path 70, 74', 18. In order
to lock the lower bypass valve open, an optional locking ball 42'
having a larger dimension as compared to locking ball 42 is dropped
into the bore hole which locks the path 18, 74' open. Deactivating
balls 44' having a larger size as compared to deactivation balls 44
due to the larger size of the ports 74' as compared to the ports 74
are then dropped into the drill string to close the ports 74'. At
the end of the procedure, the deactivation ball 90 together with
balls 44' will move through the engagement means 11 of the lower
bypass valve and will be collected by a ball catch assembly 24.
[0162] FIG. 18 shows an apparatus 1800 according to another
exemplary embodiment of the invention. As in FIG. 17, also the
apparatus 1800 comprises two engagement means 11, 11' which however
have a different diameter or size for engaging balls of different
sizes. However, in FIG. 18 the ports 18, 74 of the lower downhole
tool need not be larger than those of the upper one, although this
may be preferred for LCM purposes.
[0163] The apparatus 1800 comprises a first frangible activation
ball 92 designed as a hollow sphere which is configured so that it
breaks upon exertion of a predefined mechanical load. Such a
frangible hollow sphere can be manufactured from boro-silicate
(Pyrex) to form a toughened glass. In a similar fashion as
activation ball 90 in FIG. 17, the frangible activation ball 92 can
be dropped into the drill string to be engaged by the engagement
means 11 of the upper downhole tool. This will open, in accordance
with the above description, the fluidic path 70, 74, 8 since the
ports 74, 8 are then in alignment. Hence, bypassing of fluid is
then possible via the fluidic path 70, 74, 8. Upon further
increasing the pressure above the arrangement of engagement means
11 and frangible activation means 92, the frangible activation
means 92 will break and small pieces thereof will move downwardly
through engagement means 11 as well as through engagement means 11'
of the lower downhole valve. This will again close the upper valve
without influencing the operation mode of the lower valve.
[0164] Subsequently, a second frangible activation ball 94 may be
dropped into the drill string which has a size small enough to pass
the engagement means 11 of the upper downhole tool without
interaction. However, since the inner diameter of the engagement
means 11' of the lower downhole tool is smaller than that of the
upper downhole tool 11, the second frangible activation means 92
will be engaged by the engagement means 11' to thereby open the
lower valve. Opening the lower valve in this respect means that the
ports 74, 18 are brought in alignment with one another, since the
increased pressure above the arrangement 11', 94 is larger than the
biasing force of the spring 80. A further increase of the pressure
will then also break the frangible activation means 94 into pieces
which are pumped away so as to again close the lower valve.
[0165] FIG. 19 shows an apparatus 1900 according to another
exemplary embodiment of the invention. In this embodiment, two
split-flow downhole tools are combined, each of which functioning
in a similar way as described referring to the apparatus 1600.
[0166] In this embodiment, the second restriction device 38 is
provided with a wire line 98 so that the second restriction device
38 can be pulled out of the bore hole after having closed the
second through-flow passage 32.
[0167] The operation of the apparatus 1900 is as follows: The first
restriction device 30 is dropped in the drill string and engages
with the engagement means 11 of the upper downhole tool of FIG. 19.
In the same way as described above referring to FIG. 16, this
splits the flow into an axial component and a lateral bypass
component. In order to again close the upper valve, the second
restriction device 38 is dropped into the bore hole which engages
the engagement portion 40 of the first restriction device 30. This
closes the upper downhole valve by forcing the first restriction
device 30 through the first engagement means 11 to travel downwards
towards the engagement means 11 of the lower downhole valve of FIG.
19. Since the second restriction device 38 is connected to the
wireline 98, it cannot travel downwards, but can be pulled upwards
out of the bore hole.
[0168] The skilled person will understand that any desired ball or
dart disclosed in any of the embodiments may also be equipped with
a wireline so as to be retrievable from the bore hole. By taking
such a measure, if desired or required, it may be prevented that a
drop device used for operating the upper downhole tool could have
an undesired impact on the lower downhole tool.
[0169] Coming back to FIG. 19, a similar split flow procedure as
performed with the upper downhole valve can be repeated with the
lower engagement means 11. Its through flow path can either also be
closed again by the second restriction device 38 having the
wireline 98 or alternatively by a third restriction device 38'
which does not necessarily need a wireline.
[0170] After use, the restriction devices 30, 38' can be collected
in a catch assembly 24.
[0171] FIG. 20 shows an apparatus 2000 according to still a further
exemplary embodiment of the invention, in which three downhole
valves are serially connected in a single drill string. In the
shown embodiment, three autolock devices, as compared to two
autolock devices shown in FIG. 17, are connected in series.
Correspondingly, a third downhole valve has third port means 100,
and third sleeve means 10 are also provided. The third sleeve means
10 are provided with ports 74''. A single activation ball 90 can be
used for all three downhole valves, each having an engagement means
11 for engaging activation ball 90. However, the locking is
performed with separate locking balls 42, 42', 42'' of plastic
material which can be locked between the respective sleeve 10 and
ports 8, 18, 100. Deactivation means 44, 44' and 44'',
respectively, can be used as well. In the shown embodiment, the
size of the locking means and deactivation means is the larger the
lower the corresponding downhole valve is located.
[0172] FIG. 21 to FIG. 26 show cross-sectional drawings of a
downhole circulation apparatus 2100 embodying the present invention
showing a combination of a ball operated downhole tool 2102 above
and a clutch mechanism downhole tool 2104 below.
[0173] In the tandem device shown in FIG. 21 to FIG. 26, the two
downhole tools 2102, 2104 for bypassing drilling fluid are serially
coupled, one of which (2104) being a clutch mechanism. There is a
first biasing means 12 (such as a spring) biasing the clutch
mechanism to the closed state and a separate second biasing means
12 (such as another spring) biasing the other downhole tool (2102)
to the closed state.
[0174] FIG. 21 shows the complete tandem device having the
ball-operated downhole tool 2102 on top (FIG. 22 and FIG. 23 show
details) and clutch mechanism downhole tool 2104
(pressure-operated) below (FIG. 24 to FIG. 26 show details).
[0175] In addition to the explicitly described combinations of
downhole tools, many other combinations of different downhole tools
are possible, i.e. any desired combination of autolock tools and/or
split-flow tools and/or frangible activation means tools and/or
clutch mechanisms.
[0176] It will be appreciated by person skilled in the art that the
above embodiment has been described by way of example only and not
in any limitative sense, and that the various alternations and
modifications are possible without departure from the scope of the
invention as defined by the appended claims.
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