U.S. patent number 3,908,769 [Application Number 05/410,589] was granted by the patent office on 1975-09-30 for method and means for controlling kicks during operations in a borehole penetrating subsurface formations.
This patent grant is currently assigned to Shell Oil Company. Invention is credited to Frans DEKlerk, Philip W. Pattynama, Willem Schuyf, Bart Tent.
United States Patent |
3,908,769 |
Schuyf , et al. |
September 30, 1975 |
Method and means for controlling kicks during operations in a
borehole penetrating subsurface formations
Abstract
In well drilling operations, a down-hole packer is carried by a
drill string, above the drill bit, which is adapted to by inflated
by use of drilling fluid under pressure when the drill bit is
raised off the bottom. After the packer is set against the wall of
the borehole, communication between the interior of the drill
string and the well annulus is provided whereby a heavy drilling
fluid may be pumped into the well displacing from the well a
lighter drilling fluid, thereby providing a method for controlling
pressure kicks during well drilling operations.
Inventors: |
Schuyf; Willem (The Hague,
NL), Tent; Bart (Rijswijk, NL), Pattynama;
Philip W. (Rijswijk, NL), DEKlerk; Frans
(Rijswijk, NL) |
Assignee: |
Shell Oil Company (Houston,
TX)
|
Family
ID: |
26236022 |
Appl.
No.: |
05/410,589 |
Filed: |
December 6, 1973 |
Foreign Application Priority Data
|
|
|
|
|
Jan 4, 1973 [GB] |
|
|
564/73 |
Sep 10, 1973 [GB] |
|
|
42472/73 |
|
Current U.S.
Class: |
175/48; 166/184;
166/187; 166/188 |
Current CPC
Class: |
E21B
33/127 (20130101); E21B 21/103 (20130101) |
Current International
Class: |
E21B
21/00 (20060101); E21B 33/127 (20060101); E21B
21/10 (20060101); E21B 33/12 (20060101); E21B
033/127 () |
Field of
Search: |
;166/149,150,151,185,184,188,187,122 ;175/48,50 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Purser; Ernest R.
Assistant Examiner: Pavreau; Richard E.
Claims
We claim as our invention:
1. Means for controlling kicks during operations in a bore hole
penetrating subsurface formations, said means being adapted to be
included between two portions of tubular bore hole equipment and
comprising:
an elongated body member with a conduit longitudinally
therethrough, and a first valve system arranged in this conduit for
controlling the passage of fluid therethrough;
an inflatable packer around the body member and comprising an
elastic annular element connected at each end thereof to an annular
sleeve arranged slidingly in axial direction on part of the outer
wall of the elongate body member and sealing against the said outer
wall; and
a second valve system to control fluid communication between the
exterior of the body member and the conduit extending
longitudinally through the body member and between the interior of
the inflatable packer and the said conduit through the body member,
said second valve system including one of the annular sleeves,
means being provided for retaining said sleeve during inflation of
the packer when supplying fluid to the interior thereof in a
position in which it closes off the communication between the
exterior of the body member and the conduit through the body member
but allows communication between this conduit and the interior of
the inflatable packer.
2. Means according to claim 1, wherein the annular sleeve forming
part of the second valve system has a cross-section greater than
the crosssection of the other annular sleeve, and is mounted on
part of the body member having a smaller cross-section than the
part on which the other annular sleeve is mounted.
3. Means according to claim 1, wherein the annular sleeves of the
packer are freely rotatable around the body member.
4. Means according to claim 1, wherein the annular sleeve forming
part of the second valve system is movable between two end
positions and cooperates with at least one bore in the wall of the
body member, which interior of the packer in the second and third
position, and the other sleeve closing off the entrance to the bore
leading from the exterior of the body member to the cylinder/piston
system of the first valve element of the first valve system in the
third position.
5. Means according to claim 4, wherein the second valve system
includes fluid control means arranged in the conduit through the
body member and actuatable by the first valve system, these fluid
control means being displaceable between two end positions and
closing off the bore in one of the end positions.
6. Means according to claim 5, wherein a vent conduit is provided
to vent the interior of the packer to the exterior of the body
member in one of the end positions of the sleeve and of the fluid
control means of the second valve system.
7. Means according to claim 5, wherein the first valve system
comprises a first valve element and a second valve element, each
element being movable between two end positions, means adapted to
urge the valve elements apart to positions in which there is a free
passage through the conduit extending longitudinally through the
elongated body member, and dampening means adapted to control the
relative speed between the elements when they are urged apart, the
two valve elements when contacting each other closing off the
passage through the said conduit, the first valve element being a
non-return valve and the second valve element being coupled to the
fluid control means of the second valve system.
8. Means according to claim 7, wherein the dampening means operate
only when the valve elements of the first valve system are moved in
the direction of the flow of drilling liquid when passing through
the tubular borehole equipment.
9. Means according to claim 7, wherein the dampening means is of
the hydraulic type and arranged between the two valve elements of
the first valve system.
10. Means according to claim 7, wherein the dampening means is of
the hydraulic type and arranged between the first valve element of
the first valve system and the body member.
11. Means according to claim 7, wherein a cylinder/piston system is
arranged between the second valve element of the first valve system
and the body member, said cylinder communicating with the exterior
of the body member via a bore in the wall of the body member, which
bore can be closed off by that annular sleeve of the inflatable
packer, which sleeve does not form part of the second valve
system.
12. Means according to claim 7, wherein a cylinder/piston system is
arranged between the first valve element of the first valve system
and the body member, said cylinder communicating with the interior
of the inflatable packer.
13. Means according to claim 7, wherein a cylinder/piston system is
arranged between the first valve element of the first valve system
and the body member, said cylinder communicating with the exterior
of the body member via a bore in the wall of the body member.
14. Means according to claim 13, wherein the packer cooperates with
the body member via a pin and slot system allowing the packer when
inflated to be positioned in three distinct positions with respect
to the body member, the annular sleeve forming part of the second
valve system closing off the communication between the exterior of
the body member and the conduit extending through the body member
in the first position and second position, said sleeve closing off
the communication between the said conduit and the bore in one end
position of the sleeve forms a communication between the conduit
through the body member and the exterior of the body member, and in
the other end position of the sleeve forms a communication between
the conduit through the body member and the interior of the
inflatable packer.
15. Means according to claim 7, wherein a cylinder/piston system is
arranged between the first valve element of the first valve system
and the body member, said cylinder communicating with the conduit
extending axially through the body member via a bore, the entrance
to which bore being controlled by the fluid control means of the
second valve element that are arranged in the conduit.
16. Means according to claim 15, wherein a second cylinder/piston
system is arranged between the first valve element of the first
valve system and the body member, said cylinder communicating with
the interior of the packer and with the exterior of the body member
via separate communication bores in the wall of the body member,
the communication between the cylinder and the exterior of the body
member being controlled by an annular sleeve of the packer, and the
communication between the cylinder and the interior of the packer
being controlled by a piston on the first valve element of the
first valve system.
17. Means according to claim 1, wherein the annular sleeve forming
part of the second valve system is movable between two end
positions and cooperates with a first bore in the wall of the body
member and forming a communication between the conduit through the
body member and exterior of the body member, and with a second bore
in the wall of the body member and forming a communication between
the conduit through the body member and the interior of the
inflatable packer, said annular sleeve closing off the first bore
in one of the end positions and closing off the second bore in the
other end position.
18. Means according to claim 17, wherein the second valve system
includes fluid control means arranged in the conduit through the
body member and actuatable by the first valve system, these fluid
control means being displaceable between two end positions and
closing off the second bore in one of the end positions.
19. Means according to claim 1, wherein the body member comprises a
telescopic joint with torque transmission means, said first valve
system comprises a first valve element connected via a connecting
element to one of the elements of the telescopic joint and movable
between two end positions, said first valve element closing off the
passsage through the conduit extending through the body member in
the extended position of the joint and leaving this passage free in
the contracted position of the joint.
20. Means according to claim 19, wherein the first valve system
comprises a second valve element being of the non-return type and
displaceable between two end positions along the connector element,
said second valve element closing off the passage through the said
conduit in one of the end positions.
21. Method for controlling kicks during operations in a borehole
penetrating subsurface formations, in which equipment including a
drill string and a means as claimed in claim 1 is suspended, said
method comprising the steps of:
a. stopping the operations;
b. closing off the annular space around the drill string at a level
near the entrance of the borehole and actuating the first valve
system to closing position;
c. pumping down fluid through the drill string to inflate the
packer to close off the annular space around the drill string;
d. stopping the pumping fluid;
e. displacing the drill string with respect to the inflated packer
set against the wall of the borehole, to operate the second valve
system to open the communication between the exterior of the body
member and the conduit extending through the body member;
f. opening the annular space at the level near the borehole
entrance;
g. resuming pumping of fluid through the drill string and changing
the composition of this fluid;
h. displacing fluid in the annular space by the fluid of different
composition;
i. stopping the fluid circulation and subsequently displacing the
drill string with respect to the inflated packer set against the
wall of the borehole to operate the second valve system to close
the communication between the conduit and the exterior of the body
member to deflate the packer, and
j. resuming operations.
22. Method according to claim 21, wherein the step of lifting the
drill string is included between the steps (a) and (b).
23. Method according to claim 21, in which the equipment includes
the means as claimed in claim 8 in which the first valve system is
actuated into closing position in step (b) after closing off the
annular space around the drill string at a level near the entrance
of the borehole, by temporarily opening the upper end of the drill
string and allowing an upward flow of fluid through the drill
string.
24. Method according to claim 21, wherein the actuation of the
first valve system in step (b) is performed by lifting the
equipment free from the borehole.
25. Method according to claim 21, wherein the actuation of the
first valve system in step (b) is performed by the step of closing
the first valve element thereof by lifting the equipment free from
the bottom of the borehole and by the step of closing the second
valve element thereof by opening the upper end of the drill string
and allowing an upward flow of fluid through the drill string, and
to the step of closing off the annular space around the drill
string at a level near the borehole entrance.
26. Method according to claim 21, in, and including between steps
(e) and (f) the step of measuring the pressure in the annular space
below the packer set against the bore-hole wall, said measuring
step comprising slowly lowering the pressure within the upper end
of the drill string to open the first valve system, measuring the
pressure variation in the string until the lowest value has been
reached, followed by opening the upper end of the drill string to
close the first valve system.
27. Method according to claim 21, including the step of measuring
the pressure in the annular space below the packer set against the
wall of the borehole, this step being carried out between the steps
e) and f).
28. Method according to claim 27, in which the measuring step
includes gradually varying the pressure at the entrance of the
drill string and measuring the pressure at said entrance.
29. Method according to claim 28, wherein the annular space at the
level near the borehole entrance is opened and the pressure at the
entrance of the drill string is measured when there is change in
conditions of the fluid in said annular space.
Description
BACKGROUND OF THE INVENTION
The invention relates to a method and means for controlling kicks
during operations in a borehole penetrating subsurface
formations.
During operations in a well, and in particular during drilling
operations, there is a chance that notwithstanding the close
control of the density of the mud which is applied i.a. for
plastering the wall of the hole, an unbalance occurs between the
pressure of the mud in the hole and the pressure of the fluid in
the pore space of the subsurface formation through which or into
which the borehole penetrates. This phenomenon is indicated as
"kick" and can be detected by an increase in the return of mud from
the borehole. Such increase of mud return results from fluid
flowing out of the formation into the borehole and is due to the
unbalance in pressures. If such kick is not controlled, and in
particular if the fluid entering the borehole consists fully or
partly of gas, the kick may easily lead to a blowout. As is known,
a blowing well is extremely difficult to control, and therefore all
possible measures should be taken to prevent such a blow-out by
controlling the kicks the moment they are noticed.
An object of the present invention is a means for controlling kicks
during operations in a borehole such as during drilling or during
pulling of equipment from the hole, which means will allow kick
control in a reliable and simple manner.
Another object of the present invention is a method for handling
the means suitable for controlling kicks during operations in a
borehole, which method allows a quick and safe suppression of kicks
to prevent them for developing into blow-outs.
SUMMARY OF THE INVENTION
According to the invention a means for controlling kicks during
operations in a borehole penetrating subsurface formations, which
means is adapted to be included between two portions of tubular
borehole equipment, comprises the following components:
AN ELONGATE BODY MEMBER WITH A CONDUIT EXTENDING LONGITUDINALLY
THERETHROUGH, AND A FIRST VALVE SYSTEM ARRANGED IN THIS CONDUIT FOR
CONTROLLING THE PASSAGE OF FLUID THERETHROUGH;
AN INFLATABLE PACKER AROUND THE BODY MEMBER AND COMPRISING AN
ELASTIC ANNULAR ELEMENT CONNECTED AT EACH END THEREOF TO AN ANNULAR
SLEEVE ARRRANGED SLIDINGLY IN AXIAL DIRECTION ON PART OF THE OUTER
WALL OF THE ELONGATE BODY MEMBER AND SEALING AGAINST THE SAID OUTER
WALL, AND
A SECOND VALVE SYSTEM TO CONTROL FLUID COMMUNICATION BETWEEN THE
EXTERIOR OF THE BODY MEMBER AND THE CONDUIT EXTENDING
LONGITUDINALLY THROUGH THE BODY MEMBER AND BETWEEN THE INTERIOR OF
THE INFLATABLE PACKER AND THE SAID CONDUIT THROUGH THE BODY MEMBER,
SAID SECOND VALVE SYSTEM INCLUDING ONE OF THE ANNULAR SLEEVES,
MEANS BEING PROVIDED FOR RETAINING SAID SLEEVE DURING INFLATION OF
THE PACKER WHEN SUPPLYING FLUID TO THE INTERIOR THEREOF IN A
POSITION IN WHICH IT CLOSES OFF THE COMMUNICATION BETWEEN THE
EXTERIOR OF THE BODY MEMBER AND THE CONDUIT THROUGH THE BODY MEMBER
BUT ALLOWS COMMUNICATION BETWEEN THIS CONDUIT AND THE INTERIOR OF
THE INFLATABLE PACKER.
According to the invention, method for controlling kicks during
opereations in a borehole penetrating subsurface formations in
which equipment is suspended including a drill string and the means
according to the present invention, comprises the following
steps:
a. stopping the operations;
b. closing off the annular space around the drill string at a level
near the entrance of the borehole and actuating the first valve
system to closing position;
c. pumping down fluid through the drill string to inflate the
packer to close off the annular space around the drill string;
d. stopping the pumping of fluid;
e. displacing the drill string with respect to the inflated packer
set against the wall of the borehole, to operate the second valve
system to open the communication between the exterior of the body
member and the conduit extending through the body member;
f. opening the annular space at the level near the borehole
entrance;
g. resuming pumping of fluid through the drill string and changing
the composition of this fluid;
h. displacing fluid in the annular space by the fluid of different
composition;
i. stopping the fluid circulation and subsequently displacing the
drill string with respect to the inflated packer set against the
wall of the borehole to operate the second valve system to close
the communication between the conduit and the exterior of the body
member and to open the communication between the conduit and the
interior of the packer to deflate the packer, and
j. resuming operations.
BRIEF DESCRIPTION OF THE DRAWING
The invention will now be described by way of example, with
reference to two embodiments of the invention shown in the
drawings.
FIG. 1 of the drawings schematically shows a longitudinal section
of a kick control means according to the invention;
FIG. 2 of the drawings schematically shows a longitudinal section
of an alternative construction of the kick control means according
to FIG. 1;
FIGS. 3-8 of the drawings schematically show a longitudinal section
of another construction of a kick control means according to the
invention in various positions thereof;
FIG. 3 shows the control means during drilling of the hole;
FIG. 4 shows the control means just after a kick has been
detected;
FIG. 5 shows the control means just before inflating the
packer;
FIG. 6 shows the control means with the packer in the inflated
position;
FIG. 7 shows the control means during circulation of a drilling mud
with higher density than the original drilling mud; and
FIG. 8 shows the control means during deflaction of the packer
before rsuming drilling.
FIGS. 9-14 of the drawings schematically show part of a
longitudinal section of still another embodiment of the invention
in various positions thereof:
FIG. 9 shows the control means during drilling of the hole;
FIG. 10 shows the control means just after a kick has been
detected;
FIG. 11 shows the control means just prior to inflating the
packer;
FIG. 12 shows the control means during inflation of the packer;
FIG. 13 shows the control means just prior to circulation of a
drilling mud with higher density than the original drilling mud;
and
FIG. 14 shows the control means just prior to deflation of the
packer.
The kick control means shown in FIG. 1 comprises an elongate body
member 1 having a central longtiudinally extending conduit 2
passing therethrough. The upper end of the body member 1 is
provided with coupling means 3 for coupling the body member to (not
shown) tubular equipment which is used for drilling a borehole.
This equipment may include a drill string and a drill collar string
connected to the drill string.
A packer 4 comprising two annular sleeves 5, 6 slidable arranged on
the outer wall of the body member 1, is mounted around the body
member 1 and adapted to be inflated to close off the annular space
around the body member 1 when the latter is suspended in a
borehole. This closing off can be performed by inflating the
elastic annular element 7 which is connected at the ends thereof
the annular sleeves 5 and 6. Sleeve 5 slides over a part 8 of the
body member 1 with diameter smaller than the diameter of the part 9
of the body member 1, which latter part is supporting the slidable
annular sleeve 6. Since sleeve 5 is of larger cross-section than
sleeve 6, sleeve 5 will always be forced upwards when the packer 4
is inflated by supplying pressure fluid via the bore 10 in the wall
of the body member 1. Thus, communication via bore or port 10
between the interior of the packer 4 and the conduit 2 is
maintained during inflation of the packer 4. During normal
operations, the packer 4 rests with sleeve 6 thereof on shoulder 11
of the body member 1. Inflation of the packer 4 moves the sleeve 6
upwards.
Once the packer 4 is inflated and the elastic element 7 thereof set
against the wall of the borehole (not shown), the body member 1 can
be displaced relatively to the packer 4. When lifting the body
member 1, the packer 4 is maintained at the level at which it is
set in the borehole. The bore 10 is moved past the sleeve 5 until
it forms a communication between the exterior of the body member 1
and the conduit 2. Thus, sleeve 5 and bore 10 form a valve system
which is indicated hereinafter as second valve system 12.
The lower end of the body member 1 carries a telescropic unit 13
comprising a key 14, a keyway 15 and a sleeve 16. The lower end of
sleeve 16, although being shown in one piece with the drill bit 17,
is normally formed separately thereof and coupling means are
provided for connecting the sleeve 16 to the drill bit 17. Within
the means of the present specification and claims, the bit 17 is
understood to form part of the tubular equipment which can be
suspended in a borehole. They key 14 and keyway 15 form torque
transmission means to transmit the drilling torque from the body
member 1 to the drill bit 17.
A first valve system is provided, which system comprises a first
valve element 18 co-operating with a seat 19 and a second valve
element 20 of the non-return type and co-operating with a seat 21
arranged on the lower of the body member 1. In its rest-position,
valve element 20 is maintained at a predetermined distance from the
seat 21 by valve cage 22 connected to the body member 1. Rod 23
passes through opening 24 in valve element 20 and connects the
first valve element 18 to the sleeve 16 of the telescopic joint
13.
Openings 25 are arranged in the lower end of the sleeve 16 for
passing the flow of drilling fluid from the interior of the sleeve
16 to the bit 17. These openings may be constituted by the nozzle
openings of the drill bit 17.
The operation of the kick-control means shown in FIG. 1 is as
follows.
During drilling, the kick control means shown in FIG. 1 is
suspended in a borehole by tubular borehold equipment known per se,
such as a drill string and drill collar string. The telescopic
joint 13 and the packer 4 are then in the position shown in FIG. 1.
Although there is a pressure difference between the fluid in the
conduit 2 and the fluid in the space outside the body member 1, the
elastic annular element 7 of the packer 4 is sufficiently stiff to
withstand this pressure difference and to maintain a substantially
annular form. The drilling fluid supplied from pumps at the surface
(not shown) to the bit 17 passes through the conduit 2, between
valve 18 and seat 19, between valve 20 and seat 21, and through the
openings 25.
When a kick of dangerous magnitude is noticed in the drilling fluid
system, these pumps supplying fluid to the conduit 2 are shut down
and the drill string (not shown) to which body member 1 is
attached, is lifted. The annular space around the drill string to
closed off at the entrance of the borehole at the surface by
blow-out preventers known per se (not shown). The pressure in the
borehole being higher than the pressure in the sleeve 16, the
telescopic joint 13 remains in the retract position as shown.
By opening the upper end of the drill string to atmospheric
pressure, fluid starts to flow from the hole through the openings
25 and past valve 20 and seat 21 into the conduit 2. This creates a
pressure difference across valve 20 which consequently moves onto
its seat 21 and closes off the entry to the conduit 2. When the
flow ceases, the pressures inside and outside the sleeve 16 are the
same and consequently the sleeve 16 moves downwards under influence
of its own weight and the weight of the bit 17, thereby extending
the telescopic joint 13. At the same time, the valve 18 is pulled
into its seat 19. This valve stays in its seat when subsequently
supplying fluid to the interior of the conduit 12 by starting the
pumps. The pump pressure is then raised to a valve sufficient to
inflate the packer 4 and to set the packer against the wall of the
borehole. Sleeve 5 stays in its place during inflation and bore 10
remains open. Sleeve 6 is raised to a higher level. Since the
packer 4 is clamped or forced against the wall of the borehole in
frictional fluidtight engagement therewith, the drill string and
the body member 1 can subsequently be raised with respect to the
packer 4 to move the bore 10 of the second valve system 12 to an
open position above the sleeve 5 of this valve system. The high
pressure fluid then passes out of the conduit 2 through the bore 10
into the annular space above the inflated packer 4, and by opening
the blow-out preventer means at the surface which closes the top of
the annular space, a circulation of mud can be set up via the drill
string and the annular space. By increasing the density of fluid
which is circulated into this annular space thereby displacing the
fluid of relatively lower density, the hydrostatic pressure above
the packer 4 is increased. When this hydrostatic pressure is
sufficiently high to control the kick pressure below the packer 4,
circulation of fluid is stopped and the drill string is lowered to
displace the bore 10 to the position as shown in FIG. 1. Packer 4
is thereby deflated and further lowering of the drill string causes
contraction of the telescopic joint 13 when the bit 17 is set on
the bottom of the hole. Consequenly, the valve 18 is moved out of
its seat 19 and drilling can be resumed. It will be appreciated
that the kick control means is ready for use again.
Sealing means can be arranged where necessary to prevent flow of
fluid between locations of different pressure. In particular, such
sealing means are arranged between the sleeves 5 and 6 and the
surfaces 8 and 9, respectively.
Valve 20 and valve 18 may be of shape different than shown in the
drawings. The same applies for the seats 19 and 21. If desired,
valve 20 may be omitted. The telescopic unit is then extended by
lifting the drill string after closing the passage through the
drill string and the passage through the annular space therearound
at the entrance of the borehole.
By providing a channel (not shown) of small cross-section through
the valve 18, the pressure prevailing below the inflated packer can
be measured. This allows an exact calculation of the density of the
fluid which is to be circulated into the borehole to control the
kick.
The kick control means in FIG. 2 does not comprise a telescopic
joint as the tool shown in FIG. 1. This renders the tool cheaper
and more reliable in the borehole. The body member 31 comprises a
conduit 32 and a coupling 33 for coupling the member 31 to (not
shown) tubular euqipment for carrying out operations in a hole.
Since the body member 31 carries a drill bit 34, these operations
are drilling operations and the tubular equipment is a drill
string. Suitable coupling means (not shown) are arranged between
the lower end of the body member 31 and the drill bit 34. As in
Fig. 1, the tool shown in FIg. 2 has a packer 35 comprising two
annular sleeves 36, 37 slidably over the outer wall of the member
31, and an inflatable elastic annular element 38. The sleeve 36 has
a cross-section larger than the cross-section of the sleeve 37 and
is carried by a part 39 of the member 31 which has a cross-secion
smaller than the cross-section of the part 40 of the body member
31. The lower sleeve 36 is carried by a shoulder 41 of the member
31 and the elastic annular element 38 is sufficiently stiff to
maintain the packer 35 in the position shown.
A first valve system 42 and a second valve system 43 are carried by
the body member 31.
The second valve system 43 comprises three elements, to wit the
sleeve 36, a bore 44 and an inner sleeve 45, which sleeve is
carried via a rod 46 by the first valve system 42.
The first valve element of the first valve system 42 is formed by a
non-return valve 47 and has a dampening system connected thereto.
The dampening system consists of an oil-filled cylinder 48 and a
piston 49 connected to the valve element 47. A small diameter bore
50 is arranged through the piston 49. The lower end of the valve
element 47 has an opening 51 of a size to create a pressure
difference across the valve element 47 when there is an upward flow
of fluid through this opening, which difference is sufficiently
great to move the valve element 47 upwards against the action of a
spring 53 to close around the lower end of the second valve element
54 of the first valve system 42. This latter valve element is
connected via rod 46 to the inner sleeve 45 of the second valve
system 43.
The opening 51 communicates via space 52 with opening 53A in the
lower end of the body member 31. This opening 53A may also be
formed by the jet nozzle or jet nozzle of the drill bit 34.
When the tool shown in FIG. 2 is suspended in a borehole from
tubular borehole equipment, there is an unobstructed passage for
drilling fluid supplied by pumps (not shown) via the drill string
and drill collar string to the body member 31, through which the
fluid passes along the conduit 32, the interior of sleeve 45, the
space around the second valve element 54, the passage between the
first valve element 47 and the second valve element 54, the
interior 55 of the first valve element 47, the opening 51, space 52
and opening 53A to the drill bit 34.
When a kick occurs in the borehole, the pumps are shut down by an
operator and a blow-out preventer (not shown) is actuated to close
off the annular space around the drill string at the entrance of
the borehole. Thereafter the upper end of the drill string is
opened which results in an upward flow of fluid through the opening
53A, the space 52, the opening 51 and the interior 55 of valve
element 47. This flow creates a presssure difference across the
valve element 47 which subsequently moves upwards and closes around
the valve element 54. The speed at which the valve element 47 moves
is i.a. controlled by the dampening means 48, 49 and 50.
Subsequently, the pumps are restarted and the pressure in conduit
32 is raised which results in a downward movement of the first
valve system 42. The spring 53 tries to urge the first valve
element 47 and the second valve element 54 apart during this
downward movement, but is counteracted by the dampening means 48,
49 and 50, so that the valve element 54 remains in sealing contact
with the valve element 47 until the latter is again in the position
shown in FIG. 2. The pump pressure above the first valve system 42
being higher than the kick pressure in the hole, the valve elements
54 and 47 remain in contact and close off the passabe through the
conduit 32.
The downward displacement of valve 54 effects the operation of the
second valve system 43 by the displacement of the inner sleeve 45
therby uncovering bore 44. Bore 44 then forms a communication
betweeen conduit 32 and the interior of packer 35 which results in
inflation of the packer by the high pressure fluid entering the
bore 44. Once the packer 35 is set against the (not shown) wall of
the borehole, the drill string is lifted to expose the bore 44 to
the annular space above the packer 35. The high pressure fluid then
flows into this annular space and by opening the blow-out prevent
at the entrance of the borehole, the fluid in this annular space
can be displaced by a fluid with higher density than the fluid
originally present in this annular space. This high density fluid
is supplied by the (not shown) pumps to the interior of the drill
string. When the hydrostatic pressure above the packer 35 has been
raised to a sufficient extend, the drill string is lowered again to
bring the bore 44 into communication with the interior of the
packer 35 and with the conduit 32. By gradually lowering the
pressure of the fluid in the conduit 32, the packer 35 is deflated,
and when the pressure above the closed first valve system 42 equals
the pressure in the borehole, the two valve elements 47 and 54 of
this valve system 42 separate under influence of the spring 53 and
the free passage through the conduit 32 is restored, whereafter the
operations which were being carried out in the borehole prior to
the occurrence of the kick, can be resumed.
If desired, a vent conduit can be incorporated in the second valve
system 43, to vent the interior of the packer 35 in the position of
the inner sleeve 45 as shown in FIG. 2 to the exterior of the body
member 31 at a location above the packer.
During operation of the kick control means shown in FIG. 2 to
control a kick in the manner as herein described above, the
pressure of the kick can be measured in the inflated position of
the packer. Thereto, after the drill string has been lifted to
displace bore 44 to a position above the annular sleeve 36, the
pressure within the conduit 32 is gradually lowered until a
constant pressure is reached. This pressure is the kick pressure
and starting herefrom the required density of the fluid which is to
be circulated into the annular space above the packer to control
the kick can be calculated.
The first valve system 42 has been opened by this gradual pressure
decrease in the conduit 32. To close this valve system again (as is
necessary to allow circulation of the fluid to displace the
relatively low density fluid in the annular space above the packer)
the drill string is opened at its upper end to an extend sufficient
to create an upward flow in the conduit 32 which flow displaces the
first valve element 47 of the first valve system 42 upwards to
close against the second valve element 54 of this system.
Thereafter the pressure in the conduit 32 is raised quickly to
displace the first valve system 42 downwards without allowing the
elements 47 and 54 to be separated under influence of the spring
53. Thereby, the bore 44 is brought again into communication with
the conduit 32 and the circulating step as described already
hereinabove can be carried out.
Instead of a single bore 44 as shown in FIG. 2, two bores may be
applied, the first bore forming a communication between the conduit
32 and the annular space above the packer 35 when inflated, and the
second bore forming a communication between the conduit 32 and the
interior of the packer 35. The sleeve 36 in its upper end position
closes off the second bore and in its lower end position closes off
the first bore. The inner sleeve 45 cooperates with the second bore
only.
The dampening means which control the speed at which the first
valve element 47 of the first valve system 42 can be displaced may
also be arranged between the first valve element 47 and the second
valve element 54 of the first valve system 42. These dampening
means need to function only when the first valve system 42 is
moving downwards. Thus, a channel (not shown) of larger
cross-section than the bore 50 in the piston 49 of the dampening
means may be applied to interconnect the two portions of the
cylinder 48. A non-return valve (not shown), which operates only to
close this channel when the first valve system 42 moves downwards
is incorported in this channel.
To lock the second valve element 54 of the first valve system 42 in
the closed position, a cylinder/piston system (not shown) may be
arranged between this valve element or an extension thereof and the
body member 31. The cylinder communicates by a bore (not shown)
with the space below the packer 35 when inflate, the entrance to
which bore is controlled by the position of the annular sleeve 37.
By manipulating the drill string with respect to the inflated
packer, the fluid within the cylinder can be locked up, thus
locking the second valve element 54 in the closed position
thereof.
A similar locking system as describe in the preceding paragraph may
be applied to the first valve element 47 of the first valve system
42. The cylinder of such locking system (not shown) may assist in
closing the first valve element 47, which means that the
cross-section of the bore 51 can be enlarged. This cross-section
may even be made equal to the cross-section of the passage 52. This
type of locking system is also hereinafter described with reference
to the embodiment shown in FIG. 9.
The sleeves of the packers 4 and 35 shown in the drawing both
comprise sealing element to maintain the pressure at which the
packers are inflated, when the drill string is displaced with
respect to the packers and the communication between the conduits
extending longitudinally through the body members and the packer
interior is closed off.
When the tool as shown in FIG. 2 has two bores instead of a single
bore 44 (the operation of this two-bore system being explained
above) and further has a cylinder/piston locking arrangement
cooperating with the first valve element 47 of the valve system 42
(as also explained hereinabove), the packer will have to cooperate
with the body member via a pin and slot system allowing the packer
when inflated to be positioned in three distinct positions with
respect to the body member, the annular sleeve forming part of the
second valve system closing off the communication between the
exterior of the body member and the conduit extending through the
body member in the first position and second position, said sleeve
closing off the communication between the said conduit and the
interior of the packer in the second and third position, and the
other sleeve closing off the entrance to the bore leading from the
exterior of the body member to the cylinder/piston system of the
first valve element of the first valve system in the third
position.
The construction and operation of the kick control means shown in
FIGS. 3-8 of the drawings will now be described.
It will be appreciated that the kick control means shown in FIGS.
3-8 is mounted at a suitable location in tubular euqipment used for
drilling a hole in the subsurface of the earth and that the upper
part of the elongate body member 101, as well as the lower part of
this body member, is provided with means (not shown) for coupling
the body member to the tubular equipment. This equipment may
include a drill string and a drill collar string connected to the
drill string.
The elongate body member 101 (see FIG. 3) comprises a
longitudinally extending conduit 102 passing therethrough.
A packer 104 comprising two annular sleeves 105, 106 slidably
arranged on the outer wall of the body member 101, is mounted
around the body member 101 and adapted to be inflated to close off
the annular space around the body member 101 when the latter is
suspended in a borehole. This closing off can be performed by
inflating the elastic annular element 107 which is connected at the
ends thereof to the annular sleeves 105 and 106. Sleeve 105 is
adapted to slide over a part 108 of the body member 101 with
diameter smaller than the diameter of the part 109 of the body
member 101, which part is supporting the slidable annular sleeve
106. Since sleeve 105 has a cross-sectional area larger than the
cross-sectional area of sleeve 106, sleeve 105 will always be
forced upwards during inflation of the packer 104 when pressure
fluid is supplied via the bore 110 in the wall of the body member
101. Thus, communication between the bore 110 and the interior of
the packer 104 is maintained during inflation of the packer 104.
During normal operations, the packer 104 rests with sleeve 106
thereof on shoulder 111 of the body member 101. Inflation of the
packer 104 moves the sleeve 106 upwards.
A first valve system 112 and a second valve system 113 are carried
by the body member 101.
The second valve system 113 comprises three elements, to wit the
sleeve 105, the bore 110 and a valve 114, which valve is carried
via a rod 115 by the first valve system 112, as will be explained
hereinafter. The valve 114 can be displaced between two end
positions. In the upper end position, the valve 114 rests against
the shoulder 116 of the valve housing 117 forming part of the body
member 101. In the lower end position, the valve 114 rests against
the shoulder 118 of the valve housing 117. A spring 119 resting at
one end thereof against the guide 120 for the rod 115, urges the
valve 114 to the upper end position. Guide 120 forms part of the
valve housing 117.
The annular space 121 between the two parts 114 A and 114 B of the
valve 114 communicates in the upper end position of the valve 114
with the interior of the packer 104 via the bore 110 and with the
exterior of the body member 101 via a conduit 121 A. In the lower
end position of the valve 114, which position is shown in FIG. 5 of
the drawings, the interior of the packer 104 communicates with the
conduit 102 via the bore 110, whereas the exterior of the body
member 101 remains in communications with the annular space 121 of
the value 114 via the conduit 121A.
The lower end of the rod 115 is connected to the first valve system
112. This first valve system 112 comprises a first valve element
112 and a second valve element 123 which latter element is
connected to rod 115. The first valve element 122 is movably
arranged between two end positions. In the lower end postiion
(shown in FIG. 3 of the drawings) this valve element 112 rests on
the shoulder 124 arranged on the inner wall of the conduit 102 of
the body member 101. In the upper end position (shown in FIG. 4)
the first valve element 122 rests against the shoulder 125 formed
on the housing 117 of the second valve system 113.
A spring 126 urges the first valve element 122 of the first valve
system 112 to its lower end position. This spring is arranged in an
oilfilled cylinder 127 which forms a dampening system together with
the piston 128 mounted on the first valve element 122. The piston
has one or more small diameter bores 129 passing therethrough.
Further, a cylinder/piston system is arranged on the first valve
element 122 of the first valve system 112, which cylinder/piston
arrangement consists of a cylinder 130 and a piston 131. The
cylinder 130 communicates via a bore 132 with the interior 133 of
the packer 104.
The first valve element 122 of the first valve system 112 has a
central passage 134 passing therethrough. This first valve element
122 is of the non-return type and can be closed by reversing the
flow in a direction opposite to the arrows (which indicate the way
of the drilling fluid during drilling operations). This reversed
flow will create a pressure difference over the jet nozzles (not
shown) of the drill bit (not shown). Since the cylinder space 130
below the piston 131 communicates via the bore 132, the interior
133 of the packer 104, the bore 110, the space 121 and the conduit
121A with the exterior of the body member 101, this pressure
difference will also exist over the piston 131 and the force
resulting therefrom will displace the valve 122 to a position in
which this valve 122 is in contact with valve 123. This
displacement of the valve 122 to closing position is enhanced by
the pressure difference created by the flow over the valve element
122 when passing through the passage 134 of this valve element.
The first valve element 122 of the first valve system 112 is
adapted to cooperate with the second valve element 123 of the same
system to close off the passage through the conduit 102 in the
position shown in FIG. 4 of the drawings. Suitable sealing means
(not shown) are arranged between the parts of the valve elements
122 and 123 contacting each other.
The relative position between the valve elements 122 and 123 can be
maintained (as will be explained hereinafter) during the
displacement of these elements forming the first valve system 112
to a position in which the first element 122 is in its lower end
position (see FIG. 5).
Sealing means can be arranged when necessary to prevent flow of
fluid between locations of different pressure. In particular,
sealing means may be arranged between the sleeves 105 and 106 and
the surfaces 108 and 109, respectively.
The operation of the kick control means as shown in FIGS. 3-8 of
the drawings is as follows.
When the tool is suspended in a borehole in the position shown in
FIG. 3, there is an unobstructed passage for drilling fluid
supplied by (not shown) pumps via the drill string the drill collar
string (not shown) to the body member 101 through which the fluid
passes via the conduit 102, therby passing along the side wall of
the valve housing 117, through the space between the first and
second elements 122 and 123 of the first valve system 112 and
through the central passage 134 of the valve element 122.
Subsequently, the flow (the direction of which is indicated by
arrows) passes through suitable tubular equipment (not shown) to a
drill bit (not shown).
When a kick occurs in the borehole, the pumps are shut down and a
(not shown) blow-out preventer is actuated to close off the annular
space around the drill string at the entrance of the borehole.
Thereafter, the upper end of the drill string is opened which
results in an upward flow of fluid (in a direction opposite to the
direction indicated by the arrows in FIG. 3) through the conduit
102. This flow which results from the relatively high kick pressure
in the hole creates a pressure difference across the valve element
122 and the piston 131 thereof, which valve element 122
subsequently moves upwards and closes around the valve element 123.
This position is shown in FIG. 4. The speed at which the valve
element 122 moves is, inter alia, controlled by the dampening means
127-129.
subsequently, the pumps ae restarted and the pressure in conduit
102 is raised which results in a downward movement of the first
valve system 112 (see FIG. 5). The spring 126 tries to urge the
first valve element 122 and the second valve element 123 apart
during this downward movement, but is counteracted by the dampening
means 127-129, so that the valve element 122 remains in sealing
contact with the valve element 123 until the first is in its lower
position shown in FIG. 5. The pump pressure above the first valve
system 112 being higher than the kick pressure in the hole, the
valve elements 122 and 123 remain in contact and close off the
passage through the conduit 102.
The downward displacement of valve 123 effects the operation of the
second valve system 113 by the displacement of the valve 114 which
is connected to the valve element 123 of the first valve system 112
via the rod 115. The entrance to the bore 110 is then opened (see
FIG. 5) and pressure fluid at a pressure higher than the kick
pressure in the hole can then enter the space 133 of the packer 104
and the cylinder 130 below the piston 131 mounted on the valve
element 122 of the first valve system 112 (see arrows in FIG. 5).
This results in inflation of the packer 104, whereby the packer is
pressed into sealing contact with the (not shown) wall of the
borehole. Once the packer 104 has been inflated (see FIG. 6) and
set against the wall of the borehole, the drill string is lifted to
move the body member 101 relatively to the packer clamped against
the wall so as to expose the bore 110 to the annular space above
the packer 104 (see FIG. 7). The pump is subsequently stopped.
During the displacement of the body member 101 relative to the
packer 104 set against the wall of the borehole, the fluid present
in the space 133 of the packer 104 is first closed off from the
conduit 102 and subsequently further compressed by the displacement
of the annular sleeve 105 (which has a relatively large
cross-section compared to the sleeve 106) towards the annular
shoulder 135 between the parts 108 and 109 of the body member 101,
over which parts the annular sleeves 105 and 106 are displaced. The
pressure in the space 133 is thus increased to a value higher than
the pressure in the conduit 102 at the level of the packer 104,
which results in upward displacement of the valve member 122 of the
first valve system 112. During this latter operation, the packer
104 remains in sealing contact with the wall of the borehole and
with the body member 101.
The difference in volume of the cylinder space 130 in the position
of valve element 122 shown in FIG. 6 and in the position of this
valve element 122 shown in FIG. 7 equals the difference in volume
of the space 133 of the packer 104 in these two positions. In the
embodiment as described here, the sleeve 105 contacts the shoulder
135 at the end of the stroke, whereas the same time the valve
element 122 contacts shoulder 125 of the valve housing 117.
After the valve element 122 has been displaced to the position
shown in FIG. 7, the pressure of the kick (that a is the pressure
of the fluid in the annular space around the drill string but below
the inflated packer 104) can be measured as follows.
In the position shown in FIG. 7, the upper end of the annular space
above the packer 104 is still closed off. If this annular space
contains liquid only and the entrance to the drill string is closed
off prior to stopping the pump, the pressure prevailing in conduit
102 just above the valve system 112 will be higher than the kick
pressure prevailing in the conduit 102 but below the valve system
112. By gradually lowering the pressure in the conduit 102 above
the valve system 112 (e.g., by a controlled blowing off the
pressure at the top of the drill string) a situation will be
reached at which the pressures above and below the valve system 112
are substantially equal, which will result in an upward movement of
the combination of the valve 114 and the valve element 123, which
combination then acts as a measuring piston. This upward movement
is haltered by the valve 114A when contacting the shoulder 116.
Then the communication between the conduit 102 and the bore 110
(which latter in the position shown in FIG. 7 communicates with the
annular borehole space above the packer 104) will be closed. The
pressure then measured at the top of the drill string is equal to
the kick pressure minus the pressure created by the hydrostatic
column in the drill string and by the spring 119. The moment at
which the valve 114 closes off the entrance to bore 110 can be
detected by observing the pressure decline in the annular borehole
space above the packer 104.
However, if the annular space above the packer 104 contains a fluid
partly consisting of gas, kick pressure measurement will have to be
performed in another manner than described above. It will be
appreciated that in this case, when the string is displaced to
bring the bore 110 into communication with the annular space above
the packer 104 and the pump is stopped, the pressure in the drill
string will fall below the kick pressure due to the compressibility
of the gas present in the annular space above the packer 104.
Consequently the valve 114 will be moved upwards to the position as
shown in FIG. 4 under influence of the kick pressure acting on the
lower end of the valve element 123. The communication between the
bore 110 and the conduit 102 is broken in this position of the
valve 114. Subsequently the pressure in the drill string is
gradually increased by a controlled supply of pressure liquid at
the entrance of the drill string. At the same time the behaviour of
the pressure in the annular space above the packer 104 is observed.
When the pressure inside the drill string has risen to a value at
which the pressure just above the valve 114 is slightly greater
than the sum of the kick pressure below the valve element 123 and
the pressure exerted by the spring 119, the valve 114 will be moved
downwards, therby opening the entrance to the bore 110. This
movement can be ascertained by observing the pressure in the
annular space above the packer 104, which pressure will then start
to rise. The pressure measured at that particular moment at the top
of the drill string is then equal to the kick pressure minus the
pressure created by the hydrostatic column in the drill string and
by the spring 119.
It will be appreciated that during the above-described pressure
measuring steps, the space below the packer 104 remains isolated
from the rest of the hole as well as from the interior of the drill
string, thus preventing the entrance of any high pressure fluid
into the hole or the drill string. In particular, the entrance of
high pressure gas, which would hamper the exact measuring of the
kick pressure, is prevented. This isolation of the kick zone from
the rest of the hole is obtained by the action of the valve element
123 and the valve 114, which combination acts as a measuring
piston.
It will be understood that, if desired, the pressure variation
performed at the top of the drill string to measure the kick
pressure, may be carried out more than once. Thus, the pressure at
the entrance may first be decreased to a value at which the valve
114 moves upwards, and subsequently be increased to a value at
which this valve 114 moves downwards. Also this pressure may first
be increased and subsequently be decreased.
To be absolutely sure that no gas is present either in the drill
string, or in the annular space above the packer 104, the fluid
present in these spaces may be circulated out by a liquid. This
circulation may be in the direction of the arrows shown in FIG. 7,
or in the direction opposite thereto.
By measuring the pressure as described above, the kick pressure can
be calculated and a mud with specific density sufficient to control
the kick is then prepared. Subsequently, this mud is circulated
into the drill string at a pressure sufficient to move the valve
114 and valve element 123 downwards against the kick pressure and
the action of spring 119 so as to open the entrance to bore 110
(see FIG. 7) and thus allowing the mud with relatively low density
as present in the drill string and the annular borehole space above
the packer 104 to be replaced by the heavier mud. To allow such
circulation, the upper end of the annular borehole space is opened
and the mud pumps are started to pump the new mud down through the
drill string.
When the annular borehole space is filled with mud having a
relatively high density, the circulation of mud is stopped and the
drill string is moved relatively to the packer 104 set against the
wall of the borehold. Consequently, the valve 114 moves upwards
thereby bringing one side of the bore 110 into communication with
the conduit 121A. Further, the other side of the bore 110 is
brought into communication with the interior 133 of the packer 104.
This position is shown in FIG. 8 and the arrows indicate the flow
of liquid out of the cylinder spacer 130 and the interior 133 of
the packer 104. Consequently, the valve member 122 moves downwards
thereby reopening the passage through conduit 102, and the packer
is deflated and under influence of its elasticity obtains the
original position thereof as shown in FIG. 3.
Drilling operation can now be resumed by pumping the mud with
relatively high density down through the drill string and by
rotating the drill string.
It will be appreciated that since the packer 104 can be placed just
above the drill bit (not shown), the present tool allows a
replacement of substantially the total amount of mud present in a
borehole that is being drilled.
By lifting the drill string, the packer 104 can be set at any
desired level in the hole, which allows setting of the packer
against competent parts of the wall of the borehole.
During normal operations carried out by tubular equipment in which
the present tool is incorporated, the packer 104 cannot be inflated
inadvertently, since inflation of the packer requires first a
reverse liquid flow in the tubular equipment.
If desired, a spring (not shown) may be inserted between the sleeve
106 and the shoulder 111. This results in an available stroke
length for sleeve 106 sufficiently large to allow opening of bore
110 to the exterior space of the body member 101 when displacing
the string with respect to the inflated packer, even if this packer
is set against the wall of a hole having a diameter only slightly
greater than the outer diameter of the body member 101.
It is further remarked that in the position of the packer 104 and
the valve element 122 as shown in FIG. 7, the sleeve 105 and the
valve element 122 need not necessarily be in contact with the
shoulders 135 and 125 respectively. It will be sufficient if only
one of the shoulders is contacted by the cooperating member.
However, the valve element 122 should have been raised sufficiently
to remain in sealing contact with the valve element 123 when the
latter is raised to its upper end position (vide relative position
of valve element 122 and 123 shown in FIG. 4).
The kick control means can also be operated to control kicks that
occur during operations in the borehole other than drilling. Such
other operations may include pulling of equipment out of the
well.
Since the dampening means need to function only when the first
valve system 112 is moving downwards, a channel (not shown) of
larger cross-section than the bores 129 in the piston 128 of the
dampening means may be applied to interconnect the two parts of the
cylinder 127. A nonreturn valve (not shown), which operates only to
close this channel when the first valve element 122 moves
downwards, is incorporated in this channel.
The construction and operation of the kick control means shown in
FIGS. 9-14 of the drawings will now be described.
The main difference between the embodiments of the invention shown
in FIG. 9 and FIG. 3 resides in the locking system that is used for
locking the first valve element of the first valve system in the
upper position thereof. A further difference is the position of the
opening for draining mud from the inflatable packer during
deflation thereof. This opening is positioned near the lower end of
the packer and thus obviates collection of solids settled out of
the mud in the lower part of the packer interior.
Just as the kick control means according to FIG. 3, the kick
control means according to FIG. 9 is mounted at a suitable location
in tubular drilling equipment used for drilling a hole. Thereto,
the upper and lower ends of the elongated body member 201 comprise
screw couplings (not shown) for coupling the body member 201 to the
tubular equipment.
The body member 201 comprises an axially extending conduit 202.
Further, a packer 204 is slidingly mounted on the outer wall of the
body member 201, this packer comprising two annular sleeves 205 and
206, and an elastic annular element 207 connected thereto. The
outer surface of the body member 201 comprises a stop member 208
for limiting the downward stroke of the sleeve 205. The right
surface 209 of the body member 201 limits the upward stroke of this
sleeve 205. A spring 210 is arranged below the sleeve 206 to keep
the packer 204 in the position shown in FIG. 9 when deflated and in
the position shown in FIG. 12 when inflated. In both positions, the
bore 211 is closed off by the sleeve 205 from communication with
the space outside the body member 201.
In the deflated position of the packer 204 as shown in FIG. 9, the
interior 212 of the packer communicates via bore 213, space 214 and
bore 215 with the exterior of the body 201. This bore 215 is closed
off by the sleeve 206 from communication with the exterior of the
body 201 when the body 201 is lifted with respect to the inflated
packer 204 to the position shown in FIG. 13 of the drawings.
Two valve systems are arranged inside the passage 202 through the
body member 201. The first valve system 216 comprises the sleeve
valve 217 and the valve body 218. The upper part of the sleeve
valve 217 (which is a non-return valve) can cooperate with the
valve body 218. This valve body 218 is connected to the ring valve
219 A of the second valve system 219. The sleeve 205 and the bore
211 form part of the second valve system 219. During drilling, the
right valve 219A of the second valve system 219 is kept in the
position shown in FIG. 9 by the action of the spring 220, whereas
the sleeve valve 217 of the first valve system 216 is maintained in
its lower position by the action of the spring 221. The spring 221
is mounted in an oil-filled dampening chamber 222 comprising a
piston 223 with bore 224.
The sleeve valve 217 comprises three more pistons 225, 226 and 227.
Piston 225 cooperates with a cylinder space 228 that communicates
with the axially extending conduit 202 via a bore 229. The bore 229
is closed off in the position shown in FIG. 12 of the first and
second valve systems 216 and 219 thereby trapping liquid in the
cylinder space 228 and preventing downward movement of the sleeve
valve 217. Piston 226 closes off the cylinder space 214 at the
upper end thereof. When supplying a high-pressure liquid to the
space 214, the sleeve value 217 moves upwards to the position shown
in FIG. 10 under influence of this pressure which operates on the
piston 226 in the beginning of the stroke, and on piston 227 at the
end of the stroke.
In the position of valve 218 as shown in FIG. 13, the sleeve valve
217 is locked in its upper position by the liquid pressure exerted
in the cylinder space 234 as will be explained hereinafter.
In all positions of the sleeve valve 217, the space 230 (see FIG.
9) above the piston 226 is vented via the bore 231.
The operation of the kick control as shown in FIGS. 9-14 of the
drawings is as follows.
The position of the first and second valve systems 216 and 219
during normal drilling is shown in FIG. 9. The flow of drilling
fluid is indicated by the arrows 232. The pressure of the drilling
fluid passing through the central conduit 202 acts (via the bore
231) on the upper side of the piston 226 of the valve sleeve 217 of
the first valve system 216. Since this pressure is larger than the
pressure outside the body 201, which pressure inter alia acts (via
the bore 215) on the lower side of the piston 226, the sleeve valve
217 remains in the lower position thereof as shown in FIG. 9.
When a kick occurs, the blow-out preventers on top of the hole are
closed and the supply of drilling liquid to the conduit 202 is shut
down by the drilling operator. By opening the top of the drill
string to atmospheric pressure, the pressure above the piston 226
drops below the pressure outside the body member 201 (and acting
below the piston 226). As a result thereof, the sleeve valve 217 is
moved upwards to the position shown in FIG. 10, thereby compressing
spring 221. The upper end of the sleeve valve 217 closes around the
valve body 218 thereby closing off the passage through the axial
conduit 202.
Thereafter the supply of liquid to the drill string is resumed and
the pressure above the valve body 218 is increased to displace the
valve body 218 downwards (see FIG. 11) against the action of the
spring 220, thereby also displacing ring valve 219A of the second
valve system and opening the bore 211 to allow pressure fluid to
flow out of conduit 202 (see arrows 233 in FIG. 12) to the interior
212 of the packer 204, thereby inflating the elastic annular member
207 to press this member against the wall of the bore hole (not
shown). The sleeve valve 217 is prevented from downward movement by
the action of the dampening means 221-224 and subsequently remains
in its upper position since the bore 229 is closed off by the valve
body 218 thereby trapping the liquid in the cylinder space 228.
During inflation of the packer 204, the lower sleeve 206 of the
packer is displaced upwards by the spring 210. The sleeve 205 of
the packer 204 remains in its upper position, and the bore 211
remains open for the supply of liquid to the interior 212 of the
packer 204.
Subsequently, the supply of liquid to the passage 202 is stopped,
which results in a drop of pressure in the space above the valve
body 218, which body then moves upwards together with the ring
valve 219A thereby closing off the bore 211 (see FIG. 13).
Thereafter, the drill string - in which the kick control means of
FIGS. 9-14 is mounted - is lifted and the body member 201 is
displaced upwards (see FIG. 13) with respect to the packer 204
which is clamped against the (not shown) wall of the bore hole. As
a result of this displacement, the bore 211 which used to
communicate with the interior 212 of the packer 204, is now brought
into communication with the exterior of the bore hole above the
packer 204, whereas the bore 215 which used to communicate with the
exterior of the body 201, is brought into communication with the
interior 212 of the packer 204.
Subsequently, by increasing the pressure above the valve body 218,
this body will be displaced downwards together with the ring valve
219A of the second valve system (this position of ring valve 219A
is not shown in FIG. 13). The bore 211 is thereby uncovered and
pressure fluid is allowed to flow from the space above the valve
body 218 to the space above the packer 204 in the bore-hole. As
explained already in detail with reference to the embodiment shown
in FIGS. 3-8, the pressure fluid may be of a relatively large
density to displace fluid of relative low density in the annular
space of the bore-hole. Also, the pressure prevailing below the
valve body 218 can be measured to get information on the kick
pressure. This pressure measurement can be carried out in the same
manner as explained with reference to the embodiment shown in FIG.
7 of the drawings.
It will be appreciated that during all the operations carried out
during pressure measuring and during circulation of drilling fluid
through the bore 211, the sleeve valve 217 will remain in its upper
position since downward movement thereof is prohibited by the
liquid trapped below the piston 227. Though this liquid is via bore
215 in communication with the interior 212 of the packer 204, this
liquid cannot escape from space 234 as the packer 204 cannot be
further inflated.
After a sufficient amount of fluid has been transferred from the
conduit 202 to the annular space above the packer 204, the pump
supplying this liquid is stopped. The pressure in conduit 202 above
the valve 218 is lowered and the valve body 218 together with ring
valve 219A moves upwards thereby closing off the bore 211 (see
position shown in FIG. 13).
Thereafter, the body member 201 is lowered (see FIG. 14) with
respect to the inflated packer 204 by lowering the drill string
(not shown) until the ring surface 209 of the body member 201
contacts the sleeve 205. The bore 215 is uncovered by this
displacement and the liquid can escape from the cylindrical space
234 to the exterior of the body member 201 under influence of the
displacement of sleeve valve 217 which is moved downwards by the
action of spring 221. The liquid in dampening chamber 222 is then
displaced through the port 224. In the lower position of the sleeve
valve 217 (which position is the same position as shown in FIG. 9)
the interior 212 of packer 204 communicates via the bore 213 and
the space 214 with the bore 215 and the drilling fluid present in
the packer 204 is dispelled therefrom under influence of the
elasticity of the annular member 207. Any solids that have settled
out in the lower part of the interior 212 of the packer 204 are
removed by the liquid flowing out of the packer. The packer in its
deflated position is ready for use again and drilling can be
resumed with the packer 204 and the two valve systems 216 and 219
in the position shown in FIG. 9.
It will be appreciated that sealing members (such as 0-seals) may
be provided on the surfaces that are used for sealing contact with
other elements of the kick control means.
Further, the annular sleeves 205 and 206 may show the same
difference in diameter as shown by the annular sleeves 105 and 106
of the embodiment according to FIG. 3 of the drawings.
* * * * *