U.S. patent application number 15/684552 was filed with the patent office on 2018-03-01 for downhole actuation system.
The applicant listed for this patent is FRAC TECHNOLOGY AS. Invention is credited to Viggo BRANDSDAL.
Application Number | 20180058173 15/684552 |
Document ID | / |
Family ID | 59895894 |
Filed Date | 2018-03-01 |
United States Patent
Application |
20180058173 |
Kind Code |
A1 |
BRANDSDAL; Viggo |
March 1, 2018 |
DOWNHOLE ACTUATION SYSTEM
Abstract
A downhole actuation system wherein a counting sleeve comprises
at least one radial opening in which at least one seat element is
arranged, the at least one seat element being capable of taking up
a first, active position in which the at least one seat element
projects into a longitudinal through-channel of the counting sleeve
and a second, passive position in which the at least one seat
element is retracted from the through-channel, the at least one
seat element in its first position forming an annular seat
configured to engage the actuating body.
Inventors: |
BRANDSDAL; Viggo; (Ytre
Arna, NO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FRAC TECHNOLOGY AS |
Ytre Arna |
|
NO |
|
|
Family ID: |
59895894 |
Appl. No.: |
15/684552 |
Filed: |
August 23, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 34/10 20130101;
E21B 2200/06 20200501; E21B 43/14 20130101; E21B 33/12 20130101;
E21B 43/26 20130101 |
International
Class: |
E21B 33/12 20060101
E21B033/12; E21B 34/10 20060101 E21B034/10; E21B 43/14 20060101
E21B043/14 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 24, 2016 |
NO |
20161353 |
Claims
1. A downhole actuation system, designed to be actuated by an axial
movement of a counting sleeve, where the counting sleeve is
arranged in a pipe section in a well, the pipe section forming a
housing for the counting sleeve, where the axial movement of the
counting sleeve is designed to be initiated by an actuating body in
the pipe section, wherein the counting sleeve comprises: at least
one radial opening in which at least one seat element is arranged,
the at least one seat element being capable of taking up a first,
active position in which the at least one seat element projects
into a longitudinal through-channel of the counting sleeve and a
second, passive position in which the at least one seat element is
retracted from the through-channel, the at least one seat element
in its first position forming an annular seat configured to engage
the actuating body.
2. The actuation system according to claim 1, wherein the at least
one seat element is an elongate element arranged along an inner
circumference of the counting sleeve.
3. The actuation system according to claim 2, wherein the at least
one seat element is a split ring.
4. The actuation system according to claim 3, wherein the split
ring is a C-ring.
5. The actuation system according to claim 1, wherein the at least
one radial opening comprises a plurality of holes arranged
circumferentially around the counting sleeve, wherein each hole has
a seat element arranged therein.
6. The actuation system according to claim 1, wherein the actuating
body is a ball.
7. The actuation system according to claim 1, wherein the actuating
body is decomposable.
8. The actuation system according to claim 1, wherein the counting
sleeve is configured to start and carry out its axial movement when
the actuating body lands on the annular seat whilst the at least
one seat element is in its first position.
9. The actuation system according to claim 1, wherein the counting
sleeve is configured to end and stop its axial movement when the at
least one seat element that forms the annular seat retracts to the
second position, whereby the actuating body is released and allowed
to move further down in the well.
10. The actuation system according to claim 1, wherein the counting
sleeve further comprises two or more longitudinally spaced radial
openings, each of which having at least one seat element arranged
therein.
11. The actuation system according to claim 10, wherein the
counting sleeve comprises a final seat, the final seat comprising:
a split ring, the split ring being configured to rest on one or
more shoulders and to be compressed to an inner diameter that is
smaller than the diameter of the actuating body.
12. The actuation system according to claim 10, wherein the
actuation system is configured to form a new annular seat when the
actuating body has axially displaced the counting sleeve a
predetermined distance.
13. The actuation system according to claim 12, wherein the
predetermined distance corresponds to the distance between two rows
of holes in which one or more seat elements are arranged.
14. The actuation system according to claim 1, comprising a cam in
the pipe section outside the counting sleeve, the cam configured to
engage the at least one seat element and bring the at least one
seat element: from the first position to the second position,
and/or from the second position to the first position.
15. The actuation system according to claim 5, wherein the counting
sleeve comprises additional circumferentially arranged holes
comprising ball seat elements, the distance between the additional
circumferentially arranged holes and an underlying annular ball
seat being adapted such that a ball lying on the annular ball seat
will press the ball seat elements out of the wellbore and into
external grooves provided in the pipe section forming a housing for
the counting sleeve.
16. The actuation system according to claim 15, wherein the ball
seat elements that are arranged in the additional circumferentially
arranged holes and are pressed into the external grooves are
configured to prevent rotation of the counting sleeve.
17. The actuation system according to claim 16, wherein the ball
seat elements that are arranged in the additional circumferentially
arranged holes and are pressed into the external grooves prevent
axial displacement of the counting sleeve over a limited distance
by adaptation of the length of the grooves, the grooves in a
downward axial direction ending when the underlying annular seat
has been established, the termination of the grooves forming seats
for the ball seat elements.
18. The actuation system according to claim 15, wherein the ball
seat elements are released into the wellbore and out of the grooves
when the actuating body that forces them into the grooves has been
dropped further down in the well.
19. The actuation system according to claim 1, wherein the number
of sets of longitudinally spaced radial openings corresponds to the
number of actuating bodies which is desired should pass before the
actuation system is triggered or actuated.
20. The actuation system according to claim 1, further comprising
friction elements arranged between the counting sleeve and the pipe
section, the friction elements configured to control, brake and/or
stop the axial movement of the counting sleeve, the friction
elements consisting of at least one of: a split ring, a rough
surface, a coating, ridges, c-clip rings, shear rings, or shear
pins.
Description
[0001] The present invention relates to a downhole actuation system
for use with a well, for example a petroleum well.
BACKGROUND
[0002] An oil well normally consists of one or more pipes within
one another that are run down a borehole, the outer layer or layers
known as a "casing", an inner production tubing extending virtually
the length of the borehole, and control lines. The casing protects
the inner production tubing and holds the formations surrounding
the well in place so that they do not collapse into the well. They
also protect against unwanted inflow of fluids from the surrounding
formations.
[0003] During the completion and start-up of gas and oil wells it
is in some cases necessary to carry out a fracturing job or other
operations. When a fracturing job has to be done, it will typically
be required to pump a fluid into the reservoir under high pressure
so as to cause the shale or formation to fracture. This is done to
obtain a large surface down in the formation through the fractures
so as to allow the gas or oil to flow more easily in towards the
production tubing.
[0004] When this type of job is to be done, it is important to
maintain good control of the pressure of the different zones in the
well, and it can also be difficult to pump sufficiently large
volumes of fluid into the well in order to obtain the required
pressure, simply because the well constitutes a large volume.
[0005] It is therefore common to divide to the well into zones.
Today, this is normally done by using rubber elements that swell up
in contact with hydrocarbons or water. These rubber elements are
usually mounted on the exterior of the production tubing that is
run into the well in the reservoir. The rubber elements thus swell
up against the formation (the well wall) and form a seal between
the formation and the tubing. If several such seals are put in
place, the well will be divided into a plurality of closed-off
zones between them.
[0006] To be able to produce the well, it is in addition usual to
install one or more valves capable of being opened and closed
between two such rubber elements that will form a zone, the purpose
of this being to give the oil/gas an opening in the tubing through
which to flow, and to make an opening through which the fracturing
fluid can flow out during the fracturing job. The division into
zones means that it is only necessary to pump a small amount of
fluid into the well. The use of such rubber packers and valves
simplifies the fracturing jobs, and there is no need to increase
pressure in the whole well, but only in the area between two
packers that constitutes a zone. This is done in that the valve or
valves in the production tubing are opened in a zone between two
packers, whilst the rest are kept closed. In this way, the well can
be fractured or produced selectively, with the option of closing
off ingress of water that occurs in another zone by closing the
valves.
[0007] Another method is to form zones by pumping cement down
through the production tubing and up through the space on its
outside such that the tubing is cemented firmly to the formation.
This cement is pumped down the production tubing from the surface
and all cement is forced out of the tubing and up through the space
on its outside in that a cement dart is pumped down after the last
cement and forces all the cement down ahead of it when it is pushed
down in the tubing by fluid pressure applied from above. The tubing
is open at the end and the cement will now flow out from this
opening and up through the space between the formation and the
tubing. This will empty the inside of the tubing of cement and at
the same time cement it firmly to the formation on the outside.
[0008] The production tubing can also now comprise a plurality of
valves along the tubing that can be opened. The division into zones
will be accomplished by using cement that seals the space between
the tubing and the formation, after which one or more valves are
opened such that a pressure is applied from the surface which is
sufficiently high to fracture the cement in the immediate vicinity
of the valve that is open, but not sufficiently high to fracture
the cement of the nearest adjacent valve. In this way, the well is
also divided into zones.
[0009] The number of such zones and the number of valves in each
zone varies according to the well conditions, but it is common to
have 5 to 30, with each zone, for example, comprising up to 10
valves.
[0010] These valves can normally be opened/closed using a wireline
intervention tool, or they can be opened by dropping a ball or
another body into the production tubing in the well, which then
comes to a stop in a valve seat. The pressure is then increased
above the ball and a slide or sleeve is pushed down to open the
valve. Normally this is achieved in that the valves arranged
uppermost in the tubing have a seat of large diameter, the seat
diameter being reduced successively downwards in the well.
[0011] By first dropping a small ball into the production tubing,
the ball will pass through the ball seats of the upper valves
(which have a large diameter) and then land on a valve seat in the
lower part of the well that is adapted to the diameter of the
ball.
[0012] The right valve can thus be selected based on the diameter
of the ball. However, such a system creates restrictions and a
successive narrowing downwards in the well. This will also be the
case if forms of actuating bodies other than balls are used.
[0013] The conventional methods and systems comprising different
seat diameter, restrictions and narrowing, are disadvantageous in
view of the operations that are to be carried out later in the
well. These operations can, for example, include well logging,
placement of plugs to close off a section permanently etc., or
simply that the restrictions in the tubing constitute production
choking. These drawbacks often result in the ball seats having to
be drilled out, which involves costly operations with the aid of
coiled tubing after the fracturing job has been done, to ensure
that the production tubing in the well has a uniform inner diameter
without restrictions and constrictions.
[0014] Patent application EP 2 360 347 A2 relates to a system where
different ball sizes have to be used for each zone. It is based on
two sleeves for actuation, an inner sleeve containing a loose ball
seat that is fastened inside an outer sleeve by some shear pins.
When the ball lands on the seat, both sleeves will move down until
a shear pin is broken and the ball is released and moves down to
the next valve where the operation is repeated, and then continues
downwards such that all the zones open.
[0015] Today, there are two solutions where balls of the same
diameter can be used in all the zones. One of these solutions has
an external indexing system that causes the sleeve to rotate, also
known as a "jay slot system", as described in US 2013/0248201. This
allows the balls to fall until the desired number of
rotations/indexations of the sleeve has been obtained. Typical for
such systems is that the largest number of rotation points is on
the upper sleeves and the smallest number on the lower ones. These
systems are expensive and complicated to produce and set up
(install), and it is particularly costly to mill the external
groove in the sleeve that is to cause rotation.
[0016] The system is also very sensitive to contaminants and
impurities in the well fluid that will enter the grooves and the
spring pocket, resulting in the system locking completely. It is
also difficult to reset the system if it is desired to carry out a
new fracturing or acid stimulation job, or close the zone.
[0017] Another known system is taught in GB 2506265. This system
has similar drawbacks as the solution mentioned above.
[0018] It is an object of the present invention to provide a
downhole actuation system which provides advantages over known
solutions and techniques in the above-mentioned or other areas.
SUMMARY
[0019] In an embodiment, there is provided a downhole actuation
system, designed to be actuated by means of an axial movement of a
counting sleeve, where the counting sleeve is arranged in a pipe
section in a well, the pipe section forming a housing for the
counting sleeve, where the axial movement of the counting sleeve is
designed to be initiated by an actuating body in the pipe section,
wherein the counting sleeve comprises at least one radial opening
in which at least one seat element is arranged, the at least one
seat element being capable of taking up a first, active position in
which the at least one seat element projects into a longitudinal
through-channel of the counting sleeve and a second, passive
position in which the at least one seat element is retracted from
the through-channel, the at least one seat element in its first
position forming an annular seat configured to form a seat for the
actuating body.
[0020] The appended claims outline further embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] An illustrative, non-limiting description of embodiments
will now be presented with reference to the appended figures,
wherein:
[0022] FIG. 1a shows a side view of a subterranean borehole
provided with a number of valve units according to an embodiment of
the present invention,
[0023] FIG. 1b shows a side view of a subterranean borehole
provided with a number of valve units according to another
embodiment of the present invention,
[0024] FIG. 1c shows a side view of a valve unit according to an
embodiment of the present invention,
[0025] FIG. 2 shows the valve unit illustrated in FIG. 1c with an
actuating body landed on a ball seat,
[0026] FIG. 3 shows an embodiment of a counting sleeve which may be
used in a valve unit,
[0027] FIG. 4 shows a close up detail of an actuating body that has
landed on an embodiment of a ball seat according to the present
invention,
[0028] FIG. 5 shows another close up detail of an actuating body
that has landed on an embodiment of a ball seat according to the
present invention,
[0029] FIG. 6 shows a close up detail of a valve unit according to
an embodiment of the present invention,
[0030] FIG. 7 shows a side view of a valve unit with an actuating
body landed on a ball seat according to an embodiment of the
present invention,
[0031] FIG. 8 shows the valve unit illustrated in FIG. 7 with an
actuating body landed on a ball seat,
[0032] FIG. 9 shows a side view of a valve unit with an actuating
body on its way to a ball seat according to an embodiment of the
present invention,
[0033] FIG. 10 shows a side view of an embodiment of a valve unit
according to the invention in an open position,
[0034] FIG. 11 shows various views of an embodiment of a valve unit
in an open position according to the invention,
[0035] FIG. 12 shows a close up detail in side view of a valve unit
in an open position of an embodiment according to the
invention,
[0036] FIG. 13 shows a side view of a valve unit with an actuating
body landed on a ball seat according to an embodiment of the
present invention,
[0037] FIG. 14 shows a close up detail in side view of an
embodiment according to the invention,
[0038] FIG. 15 shows a close up detail in side view of an
embodiment according to the invention,
[0039] FIG. 16 shows a side view of a valve unit with an actuating
body landed on a ball seat according to another embodiment of the
present invention,
[0040] FIG. 17 shows a side view of a valve unit with an actuating
body in various positions according to another embodiment of the
present invention,
[0041] FIG. 18 shows a side view of a valve unit with an actuating
body in various positions similar to FIG. 17,
[0042] FIG. 19 shows a detailed side view of an alternative ball
seat solution according to an embodiment of the present
invention,
[0043] FIG. 20 shows a detailed side view of an alternative ball
seat configuration according to an embodiment of the present
invention,
[0044] FIG. 21 shows a further side view of the alternative ball
seat configuration shown in FIG. 20,
[0045] FIG. 22 shows a side view of a valve unit with a further
alternative ball seat configuration according to an embodiment of
the present invention, and
[0046] FIG. 23 shows a perspective view of the embodiment shown in
FIG. 22.
DETAILED DESCRIPTION
[0047] Illustrative embodiments related to actuation of different
types of valves will now be described. It should, however, be
understood that the downhole actuation system may be employed for
actuation of various other functions and operations in different
types of tools or equipment.
[0048] FIGS. 1a-c show a borehole 100 for a well 101 that extends
down through an oil/gas-bearing formation 102, and where a
production string 104 extends down in the well. It can be seen that
the well 101 first extends vertically and then bends into a
horizontal direction.
[0049] FIG. 1a shows an example where nine valve units or pipe
sections 1 are installed in the well in order, section by section,
to be able to pump fluid into the formation 102 to make it ready
for the production of oil/gas.
[0050] An actuating body/ball 3 of a single size is dropped or
pumped into the well and will land on a ball seat 4 in a valve
unit. This is, inter alia, shown in FIG. 4. A constriction or cam
30 presses a plurality of ball seat elements 5 in the annular ball
seat 4 inwards and creates a seat that prevents the ball 3 from
continuing downward in the well. When the first ball 3 is dropped
into the well 101, it will land on an actuated annular ball seat 4,
which annular ball seat 4 is located in a counting sleeve 2.
[0051] This can be achieved in that the system consists of an
actuation system that preferably only has one internal, axially
movable counting sleeve 2. The internal, axially movable counting
sleeve 2 has one or more actuatable annular ball seats 4 comprising
ball seat elements 5 capable of moving into and out of a wellbore.
How this takes place is explained in more detail below.
[0052] There may be some leakage past the ball 3, the annular ball
seat 4 and the counting sleeve 2 wall, but this is marginal
compared with if the ball 3 had not been present on the annular
ball seat, and has in practice been found to be of little
significance. In most cases, it is not necessary to form an
entirely sealed connection between the ball 3, the annular ball
seat 4 and the counting sleeve 2 wall, but rather establish a flow
restriction that allows build-up of fluid pressure above the ball
3.
[0053] According to this embodiment, an axial displacement of a
counting sleeve 2 will be effected when larger pressure is formed
above the actuating balls 3 that have come to rest on an annular
ball seat in a valve. When the counting sleeve is axially
displaced, the ball seat elements 5 in an annular ball seat 4 will
retract and the ball 3 will be capable of being pumped further down
to the next annular ball seat 4 in the valve below, where the same
procedure takes place (i.e., an axial displacement of the valve's
counting sleeve), until the number of predetermined clicks in a
valve has been reached and the valve(s) opens/open. When a ball 3
is retained by an annular ball seat 4 in a counting sleeve 2, this
pressure will, as mentioned, displace the counting sleeve 2 axially
and thus displace the counting sleeve by one click.
[0054] According to one embodiment, the counting sleeve 2 is
designed to regulate flow out and in through the valve openings.
One such use may be to seal against flow through the openings of a
pipe section until the counting sleeve 2 has counted the correct
number of actuating balls (number of "clicks"), in other cases, the
purpose may be to shut off flow through the openings of the pipe
section after the correct number of actuating balls has been
counted. It should again be understood that the counting sleeve
could also be used to actuate other operations or functions, or
actuate a sequence of operations or functions.
[0055] In an exemplary embodiment of a well comprising a plurality
of valves that is divided into five zones, the uppermost valves
seen from above looking down into the well will typically have
respectively: five ball seat element rings with an actuatable
annular ball seat 4, then four, three, two and lastly the lowermost
set which will typically have one annular ball seat 4. Such a
configuration will provide a system where the bottom valve (set) is
actuated first, then the next and the next etc. As mentioned, the
sequence may be different if desired.
[0056] According to an embodiment, the system can be so designed
that all valves 1 that are run into the well as a part of the
production tubing are in an actuated position. In that case, that
means that at least one annular ball seat 4 is actuated in each
valve's counting sleeve 2. In this way, all the counting sleeves in
the successive valves will immediately be displaced axially in one
step when the first ball passes through the valves.
[0057] In the aforementioned exemplary embodiment, when a ball 3
passes through the uppermost valve, it will typically displace the
inner counting sleeve 2 one step or click, in order then to allow
the ball 3 to fall freely downwards in the well. When the ball 3
has displaced the counting sleeve 2 in the upper valve by one click
axially and released the ball, the next subsequent annular ball
seat 4 in the counting sleeve 2 in this valve will be actuated.
[0058] In the aforementioned exemplary embodiment, the valve or
valves arranged lowermost in the well will typically be designed to
open out towards the formation when the first ball 3 passes through
the row of counting sleeves 2 that are located above the lowermost
valve or pipe section 1.
[0059] Actuation and de-actuation of each annular ball seat 4 takes
place in that the counting sleeve 2 has at least one group, row or
ring of radial and circumferential throughbores or holes 6. In each
of these there is typically installed ball seat elements 5 from the
exterior of the sleeve 2. The ball seat elements 5 installed in
this group of bores or holes 6 will not be able to fall out through
the holes 6 and into the tubing as the holes will have a smaller
diameter than the ball seat elements 5. This means to say that each
hole 6 has a diameter that can be essentially constant through the
bore, apart from the end of the bore that opens in towards the
wellbore, this end being provided with a constriction which ensures
that a ball seat element 5 cannot fall out of the bore and into the
wellbore. According to an embodiment, the ball seat elements 5 have
a larger diameter than the radial thickness of the counting sleeve
2, i.e., a larger diameter than the body of the counting sleeve.
This ensures that the ball seat elements 5 either project slightly
into the wellbore (and thus can form an annular ring seat 4), or
slightly out on the exterior of the counting sleeve (such that it
can be held in a groove, pushed out of the wellbore, pushed into
the wellbore with the aid of a constriction or cam 30 etc.).
[0060] When the annular ball seat 4 formed by the groups of radial
and circumferential bores 6 and ball seat elements 5 is not in the
active position, the ball seat elements can be able to travel
freely in the bores in the counting sleeve 2 out towards the inner
wall of the pipe section. This is because the pipe section 1, in
the area around the non-active annular ball seats, has an internal
diameter greater than the external diameter of the counting sleeve
2, such that a space is formed between the pipe section and the
counting sleeve 2. The ball seat elements 5 will not be able to
fall out, but will be able to travel a limited distance outwards
such that they do not constitute a restriction inside the counting
sleeve 2. This travel will typically be limited to, for example,
slightly less than half the ball seat element's diameter. By
limiting the travel to less than the ball seat element's half
diameter, the ball seat elements are prevented from falling out of
their respective holes 6 in the counting sleeve and into the space
between the counting sleeve and the pipe section.
[0061] The annular ball seat 4 is actuated by the counting sleeve 2
either being displaced axially relative to the pipe section 1 that
houses the actuation mechanism. Actuation takes place in that the
pipe section 1 has an internal cam or constriction 30 that causes
the ball seat elements 5 to be pushed partly out into the wellbore.
These ball seat elements 5 are typically arranged in a ring, i.e.,
form a ball seat that comprises a ring of ball seat elements 5.
[0062] When a counting sleeve 2 is displaced axially by a ball 3
lying on an active annular ball seat 4, the groups of ball seat
elements 5 in the annular ball seat 4 in the relevant counting
sleeve 2 will also be displaced axially, the group of ball seat
elements 5 located in the space between the pipe section and the
counting sleeve just above the internal constriction or cam of the
pipe section being pressed partly out when the group or row of
radial, circumferential bores and ball seat elements pass the
constriction or cam. The ball seat elements, which now are pressed
partly out into the wellbore, will create a restriction
constituting an annular ball seat that the ball is unable to
pass.
[0063] At the same time as this new annular ball seat is now formed
by the ball seat elements in that they are pressed partly inwards
(into the wellbore) by the pipe section constriction or cam, the
ball seat elements in the annular ball seat previously actuated,
i.e., the previous annular ball seat located on the pipe section's
internal constriction or cam when the previous actuating ball
(previous click) reached the actuation mechanism, will be free to
be pushed partly out into the space around the counting sleeve
below the constriction or cam, the actuating ball that rested on
the previous annular ball seat being allowed to proceed further
down in the well. The actuation mechanism will now have undergone
one displacement or a click and be ready to receive and stop the
next actuating ball, after which the same can happen again or the
final actuation.
[0064] In the new space below the constriction or cam 30 between
the counting sleeve 2 and the valve or pipe section 1, the ball
seat elements 5 will have the possibility of collapsing or
retracting such that the internal restriction in the counting
sleeve which constituted the annular ball seat 4 is removed and
allows the actuating ball 3 to fall further down in the well. The
actuation mechanism has now counted a passing actuating ball whilst
the counting sleeve is displaced axially to the next position,
wherein a new annular ball seat is formed.
[0065] In some cases, it is conceivable that the actuating balls 3
will be pumped so quickly and forcefully down the well (high
pressure) that the ball seat elements lying in the annular ball
seat 4 do not manage to collapse fast enough into the space between
the counting sleeve 2 and the valve or pipe section 1 below the
constriction or cam 30, such that the counting sleeve is displaced
too far down and, for example, two displacements/clicks, one and a
half or finds another unfavourable intermediate position. This is
not desirable because count can be lost or the counting sleeve/ball
may get stuck. The ball per se will decompose, but then it will not
have passed through the valves below, such that the row of valves
is out of synchronisation. A similar situation may arise if
impurities get into the space between valve and counting sleeve
such that there is no room for the ball seat elements to collapse
into, with the same result that the valves are left in a
non-controllable position.
[0066] According to one embodiment of the invention, this can be
avoided in that above (or another suitable point on the counting
sleeve) the bores and the ball seat elements that constitute the
annular ball seat in the counting sleeve, there is bored one or
more new holes 13 for one or more elements 14 (FIGS. 3 and 4),
which per se may resemble or correspond to the different types of
ball seat elements 5 mentioned in this document. These holes 13 and
the elements 14 will be able to have the same or partly similar
properties as the ball seat elements 5 and the holes 6 that
constitute the annular ball seat 4. The position of these
additional bores or holes will advantageously be at the point that
forms the largest diameter D of the actuating balls 3, i.e., that
the actuating ball will block the bores or holes at its largest
diameter D and thus press the ball seat elements out into a space
between pipe section and counting sleeve, e.g., in the form of
groove 15 or the like.
[0067] This at least one element 14, which now is pressed out (in
the groove 15 or the like), will not be able to pass the internal
constriction or cam 30 in the valve or the pipe section 1 which
typically runs 360 degrees around in the pipe section 1 (FIG. 5).
Optionally, the groove 15 may have a determined length, where the
lower end of the groove forms a seat or a stop. Such a design will
result in the counting sleeve then being wholly or partly locked
against further axial movement, as the actuating ball rests against
an actuated annular ball seat 4 which is on the pipe section 1
constriction or cam 30 whilst the actuating ball 3 presses the ball
seat element or elements 5 out above the pipe section constriction
or cam 30, optionally the lower end of the groove which forms a
seat or a stop. Axial movement will then not be possible.
[0068] In this position the elements 14, which are pressed out (in
the groove 15 or the like), will prevent the counting sleeve from
being carried along to an uncontrollable or unfavourable
intermediate position, and that they are released as soon as the
underlying ball seat elements in the annular ball seat collapse
into the space between the valve housing and the counting sleeve.
Above such travel stop elements, a new annular ball seat will have
reached active position as a new ring of ball seat elements has
come onto the pipe section cam.
[0069] According to one embodiment of the invention, the counting
sleeve can also be locked against unwanted rotation in that one or
more grooves 15 are cut out in the pipe section constriction or cam
30, which are through-going and which correspond with a steering
mechanism in the counting sleeve that follows this cut-out or
groove. This rotation-preventing groove 15 may be the groove
mentioned above or comprise separate, dedicated grooves and one or
more elements 14.
[0070] In FIGS. 1-19 the ball seat elements 5 are shown as
spherical balls. It should be understood that these spheres are
only used as examples to illustrate the invention. Elongate dogs,
split sleeves, ellipsoid elements, square elements, semi-spherical
elements, oval elements, cylindrical, conical etc., rods or other
suitable geometries that have the property that they can slide in
and out of holes in the counting sleeve holes, are all possible
alternatives to spheres. FIG. 19 shows one such alternative
embodiment form comprising dogs.
[0071] In FIGS. 1-19 the bores or holes 6 are shown as radially
extending bores or holes, i.e., perpendicular to the axial
direction of the wellbore. It should be understood that this is
only a possible embodiment used as an example to illustrate the
invention. FIGS. 20 and 21 show alternative configurations of the
bores or holes 6, the bores or holes 6 being angled (i.e., an angle
less than 90 degrees relative to the axial direction of the
wellbore). Other angles and directions are possible. Considerations
that may form the basis for different configurations of angles and
directions may include force distribution factors, deformation as a
result of the application of large forces, impacts etc. If the ball
falls into the annular ball seat with sufficiently large force, the
geometry of the ball seat elements 5 and the holes 6 will be of
major importance in relation to how and where forces are
transferred. In embodiments corresponding to those shown in FIGS.
1-18, a large portion of the forces that strike the annular ball
seat when the ball lands, is transferred to the housing or the pipe
section around the counting sleeve, which may result in
damage/deformation. By selecting alternative geometries, e.g.,
other types of ball seat elements and/or angled holes, forces can
be distributed such that, for example, the counting sleeve absorbs
a larger portion of the forces. If the counting sleeve takes up a
larger portion of the forces, it will in turn be able to distribute
forces to the grooves 15, the cam 30, or other stop elements. Such
a design can also be advantageous if it is found that the counting
sleeve or other elements have a tendency to become stuck (deposits,
corrosion etc.), because the counting sleeve may have applied
thereto a larger force that jerks it free or overcomes unexpected
frictional forces.
[0072] It should be understood that "pipe section 1" and/or
"housing" in this connection comprises the pipe or the material
around the counting sleeve 2, in relation to which this sleeve is
displaced. This pipe or material is primarily motionless. According
to an advantageous embodiment, the only next moving parts in the
system are the counting sleeve and the ball seat elements that are
used to form the annular ball seat 4. The valve per se may comprise
other moving parts, depending on what function or functions it is
to have or operations it is to perform.
[0073] In this document, the actuating body is referred to as a
ball 5, but it should be understood that other actuating bodies
that can be dropped, pumped or run down the wellbore are also
included, e.g., a dart. Reference is also made to actuation system
and actuation mechanism. These terms are used somewhat
interchangeably.
[0074] As mentioned, it is conceivable that the ball seat elements
that are pressed out are not sufficient to prevent double counts,
as the ball seat elements in the rings that are above and below the
active annular ball seat 4 may project out slightly and cause
restrictions that can result in friction between passing actuating
balls and the counting sleeve, which may lead to an unintentionally
long axial movement of the counting sleeve. According to an
embodiment of the invention, this can be avoided in that, for
example, friction-creating elements 16; 17; 18 are installed in the
form of e.g., a split ring between the counting sleeve and the pipe
section, which creates friction between the counting sleeve and the
pipe section that is so large that only a ball lying on one active
annular ball seat on the pipe section constriction or cam will be
capable of moving the valve's counting sleeve (FIG. 14). This can
be controlled in that during pumping of the actuating balls
pressure build-ups can be monitored and a check can be made of
correct pressure build-up above the balls down through all the
valves. By correct pressure build-up is meant the pressure required
above the ball to overcome the retaining power of this split ring.
If such pressure build-ups are registered as correct for all the
valves throughout the well, it will be possible to establish with
reasonable certainty that all the counting sleeves have correctly
counted the number of balls and thus carried out the correct number
of displacements/clicks. Other friction-creating elements are also
conceivable, e.g., a rough surface, a coating, ridges, c-clip
rings, shear rings, shear pins.
[0075] According to an embodiment, this can be achieved by
equipping the last valve in each zone with a travel stop such that
the counting sleeve is not allowed to travel so far in the pipe
section that an actuating ball is dropped from the annular ball
seat on the constriction or cam in the pipe section. This travel
stop can in its simplest embodiment comprise an edge or shoulder
50, such that the lower end of the counting sleeve stops physically
against this in the pipe section before the annular ball seat 4
reaches the end of the constriction or cam 30 in the pipe section
(FIG. 18). In this way, the annular ball seat in this valve will
retain the actuating ball and block against flow down past the
actuating ball. This last valve or pipe section 1 in a zone must
also be adjusted with regard to positioning of openings in valve
housing and counting sleeve such that these coincide and are open
in such an end position.
[0076] A potential use of the invention is the possibility of
forming or shutting off communication between the wellbore and the
environment around the well, i.e., a valve. It should be understood
that the use of the actuation system according to the invention in
connection with a valve is only one example, as many of the
functions and considerations can be used or be relevant for other
applications.
[0077] A plurality of valves comprising an actuation system will be
capable of being arranged at regular or irregular intervals
downwards in the well, the number of displacements or clicks for
which the actuation mechanism is designed will determine how many
balls must be dropped to actuate the valve. The different valves
that are arranged downwards in the well can be actuated after a
desired number of passing balls. When the lower valves in a well
have been opened, fluid will typically be pumped out through the
opening in the pipe section and into the reservoir. When this
operation is complete, the next ball is dropped into the well and
this will then typically open the valve or valves in the overlying
zone in the well. It is then desirable to pump fluid out through
openings in the valve houses in this new zone and not in the zone
that has already been treated or above the zone or zones above the
new active zone. However, the sequence may be varied, e.g., in that
some valves are opened whilst others are closed. The valves can
also be opened and/or closed in graduated steps, e.g., in that each
ball and each click gives a larger or smaller valve opening.
[0078] The valve openings can comprise radial holes in the counting
sleeve that overlap corresponding radial holes in the surrounding
pipe section when the actuation mechanism has performed the number
of desired displacements or clicks. Other embodiments or positions
of valve openings are also conceivable.
[0079] Other uses of the invention may comprise actuating different
tools, functions or operations downhole in the well.
[0080] Further, it may be an advantage if the valve's inner
counting sleeve is equipped with at least one industry-standardised
profile for connection of a well tool. By a profile is meant
typically an internal cut-out. One such profile will preferably be
arranged at each end of the counting sleeve, one at the bottom for
opening by means of well tools and one at the top for closing.
[0081] When all the valves in all the groups have been opened and,
for example, a fracturing job has been carried out, there will be a
number of actuating bodies lying on the seats in the last valve in
the different zones and/or groups of valves. These must normally
exit the well again as they could block hydrocarbon flow from the
well. It is therefore an advantage that actuating bodies are used
which either have a shape or structure that allows them to travel
freely back to the surface without coming into conflict with the
seats in the valves, or that actuating bodies are used which
decompose after a certain time, such that free flow of hydrocarbons
can take place from the well.
[0082] According to one embodiment, there is also provided a
solution to the problem of resetting the valves in the starting
position in a safe manner such that they can be used for later
subsequent maintenance fracturing jobs. This is done by providing
the valve unit with a standardised tool profile to which a suitable
tool may be attached. Such attachment can be done in many ways, but
a common method will be use of coiled tubing. Then, either all the
valves can be opened forcibly by running coiled tubing or they can
be closed forcibly. This can, for example, be done by connecting to
a profile in the bottom of the counting sleeve and pulling or it up
to its end stop where the connection is released. When the counting
sleeve has been pulled back to the starting position, it will
overcome the friction in the split rings (if these are used). When
the counting sleeve has been pulled all the way up/back, it will,
e.g., shut off flow out through the openings in the valve unit. In
this preferred embodiment, the resetting tool can be run down to
the lowermost valve in the well using coiled tubing in order then
to be slowly pulled out of the well and at the same time close all
the valves in the system and reset them in the starting position in
a controlled way as the resetting tool is released when the
counting sleeve is drawn back to the starting position.
[0083] The opposite function is also conceivable where the position
is changed from open to closed by the correct number of actuating
bodies counted by the counting sleeve.
[0084] According to an embodiment, the invention provides the
possibility of reuse of the valves in that they can be remotely
opened without using well tools. By virtue of the design of the
valve and the counting sleeve, it will be possible to reuse the
valve's counting function when resetting the system to the starting
position, either with the aid of a well tool as mentioned, or by
using a ball that actuates a reset function. Normal time intervals
between fracturing jobs are typically 4-5 years, which means that
the savings also on reuse are substantial.
[0085] Other equally relevant uses may comprise, but are not
limited to: actuating well perforating guns, actuating other types
of well inflow valves, injection valves for chemicals, gas lift
valves and so-called sliding sleeves. It should be understood that
valves are only an example of the use of the actuation
mechanism/system. To the extent the terms "actuation
mechanism/system" and "valve" or "valve unit" are used, sometimes
interchangeably, "valve" or "valve unit" should only be regarded as
an example of the actuation mechanism/system according to the
invention.
[0086] To prevent hardening and blocking up during and after use
of, e.g., cement, a suitable lubricant/grease comprising sugar or
the like can be used. The sugar added to the lubricant will prevent
the cement from hardening in the area where the lubricant is
located, but will not prevent hardening of the cement/concrete that
passes the lubricant.
[0087] According to an embodiment, a lower seat that is established
can comprise a split ring 60 that is compressed instead of an
annular ring seat 4, so as to thus form a split ring seat 70. This
may be a part of the counting sleeve or a separate part that is
pushed down by the final axial movement of the counting sleeve. The
last ball that passes will actuate the split ring seat before it is
released from the counting sleeve's last annular ball seat, after
which the ball lands on the underlying split ring seat (FIG.
18).
[0088] The lowermost seat may alternatively have other designs, for
example, dogs, crescents or other suitable geometries.
[0089] A gasket (not shown) that secures additional sealing between
the ball and the final seat may advantageously be used. It is an
alternative that the last seat is held in place until actuation
with the aid of, e.g., a shear pin or split ring, such that it does
not move into an active position during vibrations, handling,
during running in the well or because of previously passed
balls.
[0090] The valve or pipe section 1 can preferably be produced in
any material suitable for installation in a well, and as a
non-exhaustive example mention may be made of some types of steel
used, such as ASI 4113, 420 mod 13% Cr, super duplex or high-grade
steel such as Inconel 718. It is also conceivable that ceramic
materials and other composite materials may be used.
[0091] The advantage of having such an underlying seat after the
valve has been opened, is that a larger contact surface between the
ball and the counting sleeve can be obtained than will be provided
by the rings of ball seat elements. It is thus possible to obtain
greater pressure tolerance and better sealing between the ball and
the seat, such that less fluid flows past and down to zones
below.
[0092] According to an embodiment, there is provided a
tubing-mounted downhole actuation system, which is designed to be
actuated by means of an axial, displacing movement of a counting
sleeve 2, where the counting sleeve 2 is arranged in a pipe section
1 of a well, the pipe section 1 forming a housing for the counting
sleeve 2, where the counting sleeve 2 comprises an interior surface
and an exterior surface, the interior surface of the counting
sleeve forming a part of the wellbore 101, where the counting
sleeve's 2 axial, displacing actuating movement is designed to be
initiated by an actuating body 3 that passes through the actuation
system through the wellbore 101. The counting sleeve 2 comprises a
circumferential row of holes 6 in which one or more ball seat
elements 5 are arranged, the ball seat elements 5 being capable of
taking up at least two positions, one first active, projecting
position 80 in which the ball seat elements 5 project into the
wellbore 101, and one second passive, retracted position in which
the ball seat elements are retracted relative to the wellbore 101,
the ball seat elements 5 in their projecting position forming an
annular ball seat 4 that is designed to form a seat for the
actuating body.
[0093] According to another embodiment, the actuating body 3 may
comprise a ball.
[0094] According to another embodiment, the actuating body may be
decomposable.
[0095] According to another embodiment, the counting sleeve 2 may
be designed to start and carry out its axial movement when the
actuating body 3 lands on the annular ball seat whilst the ball
seat elements are in their first projecting position 80.
[0096] According to another embodiment, the counting sleeve can be
designed to end and stop its axial movement when the ball seat
elements that form the annular ball seat 4 retract to and take up
their second retracted position, after which the ball 3 is released
and allowed to move further down in the well 101.
[0097] According to another embodiment, the counting sleeve can
comprise two or more circumferential rows of holes 6 in which one
or more ball seat elements 5 are arranged.
[0098] According to another embodiment, the counting sleeve can
comprise a final ball seat comprising a split ring 60, this being
designed to rest on one or more shoulders 50 and be compressed to
an inner diameter that is smaller than the diameter D of a
ball.
[0099] According to another embodiment, two or more circumferential
rows of holes 6, in which one or more ball seat elements are
arranged, may form a potential annular ball seat 4.
[0100] According to another embodiment, only one row of holes 6
forms one annular ball seat 4 at a time.
[0101] According to another embodiment, the actuation system is
designed to form a new annular ball seat 4 when the actuating body
has axially displaced the counting sleeve a predetermined distance
A.
[0102] According to another embodiment, the predetermined distance
A can correspond to the distance between two radial,
circumferential rows of holes in which one or more ball seat
elements are arranged.
[0103] According to another embodiment, the first active projecting
position 80 can be taken up with the aid of a constriction 30 in
the pipe section 1 outside the counting sleeve 2, an axial movement
of the counting sleeve 2 and the constriction 30 helping to force
the ball seat elements 50 into the wellbore and into the first
active, projecting position 80, from a second passive, retracted
position, in order there to form an annular ball seat 4 when a row
of radial, circumferential holes 6 comprising ball seat elements 5
that form an annular ball seat 4 pass the constriction 30.
[0104] According to another embodiment, the second passive,
retracted position can be taken up when a row of radial,
circumferential holes 6 comprising ball seat elements 5 passes the
constriction, an axial movement of the counting sleeve helping to
release the ball seat elements from a second passive, retracted
position into a first active, projecting position 80, in which the
ball seat elements project into the wellbore 101, when a row of
radial, circumferential holes 6 comprising ball seat elements 5
passes the constriction or cam 30.
[0105] According to another embodiment, the counting sleeve can
comprise additional circumferentially arranged holes comprising
ball seat elements 14, the distance between the additional radial,
circumferential holes and an underlying annular ball seat being
adapted such that a ball lying on the annular ball seat will press
the ball seat elements out of the wellbore and into external
grooves 15 provided in the pipe section forming a housing for the
counting sleeve.
[0106] According to another embodiment, the ball seat elements 14
that are arranged in the additional circumferentially arranged
holes and are pressed into the external grooves 15 can prevent
rotation of the counting sleeve.
[0107] According to another embodiment, the ball seat elements 14
that are arranged in the additional circumferentially arranged
holes and are pressed into the external grooves 15 can prevent the
axial displacement of the counting sleeve from being limited by
adaptation of the length of the grooves, the grooves in the
downward, axial direction ending when the underlying annular ball
seat 4 has been established, the termination of the grooves 15
forming seats for the ball 14.
[0108] According to another embodiment, the ball seat elements 14
can be released into the wellbore and out of the grooves 15 when
the ball 3 that forces them into the grooves has been dropped
further down in the well.
[0109] According to another embodiment, there can, between the
counting sleeve and the pipe section therearound and above and
below the constriction, be provided space that give sufficient room
for ball seat elements 5; 14 when they are to be in the retracted
position.
[0110] According to another embodiment, the number of rows of
radial, circumferential holes comprising ball seat elements 5 that
are to form annular ball seats 4, can correspond to the number of
balls it is desired should pass before the actuation system is
triggered or actuated.
[0111] According to another embodiment, between the counting sleeve
and the pipe section therearound, there can be provided friction
elements 17; 18 that control, brake and/or stop the axial movement
of the counting sleeve, the friction elements consisting of at
least one of the group comprising: split ring, a rough surface, a
coating, ridges, c-clip rings, shear rings, shear pins.
[0112] According to another embodiment, at least one internal
profile may be provided.
[0113] According to another embodiment, at least one internal
profile can be adapted for engagement with a tool that is adapted
to grip the profile and reset the actuation system in the starting
position.
[0114] According to another embodiment, at least one internal
profile can be adapted for engagement with a tool that is designed
to grip the profile and set the actuation system in a desired
position.
[0115] According to another embodiment, at least one internal
profile can be adapted for engagement with a tool that is designed
to grip the profile and forcibly actuate the actuation system.
[0116] According to another embodiment, the actuation system can
help to open a valve that provides communication between the
interior and the exterior of the wellbore.
[0117] According to another embodiment, the actuation system can
help to close a valve that closes off communication between the
interior and the exterior of the wellbore.
[0118] According to another embodiment, the actuation system can
help to initiate a function or operation.
[0119] According to another embodiment, the counting sleeve 2 can
engage and actuate an underlying seat 70 for the actuating body
3.
[0120] According to another embodiment, the underlying seat 70 for
the actuating body 3 can comprise a split ring 60.
[0121] According to another embodiment, the underlying seat can
comprise a gasket against the actuating body 3.
[0122] According to embodiments described herein, it is thus
provided a downhole actuation system that does not create
restrictions or a successive narrowing downward in the well, where
the actuation system can be used to actuate different types of
functions or operations. Advantageously, the system can be designed
to allow a ball of the same size to be used to open and/or close
all valves in a desired sequence. According to embodiments
described herein, an actuation system that is reliable, comprises
few moving parts, is not sensitive to contaminants or impurities in
the well fluid is provided. If desirable, the system can be so
arranged as to allow repeated usage and/or be reset.
[0123] In an embodiment, illustrated in FIGS. 22 and 23, there is
provided a downhole actuation system having a counting sleeve 2
arranged in a pipe section. The pipe section 1 forms a housing for
the counting sleeve 2, which is designed to be moved axially by
means of an actuating body 3 (equivalently as shown in FIGS. 19 and
21) which can be passed through the pipe section 1. The counting
sleeve 2 comprises a plurality of radial openings, in this case
four openings, in which seat elements in the form of c-rings 42a-d
are arranged. The c-rings 42a-d have a passive, disengaged position
in which they are spaced from the internal through-channel of the
sleeve 2, and an active, engaged position where they are engaged by
a cam 30 (equivalently as shown in FIGS. 19-21) and pushed partly
into the through-channel. A part of the c-rings 42a-d which extend
into the through-channel form an annular seat configured to engage
and support the actuating body 3.
[0124] In the embodiment shown in FIGS. 22 and 23, four c-rings
42a-d are used, however the system may be designed with more or
fewer c-rings. In this embodiment, four activation bodies 3 (e.g.,
activation balls) need to be passed through the counting sleeve 2
before fluid ports 40 in the sleeve 2 align with fluid ports 41 in
the pipe section 1 so as to provide fluid communication between the
inside and the outside of the pipe section 1.
* * * * *