Downhole cutting tool and method of use

Abstract

A downhole cutting tool and method of operating the cutting tool. The cutting tool (10) has first and second flow pathways through the tool body (12) and a switching mechanism operated by axial force via weight-set or drop ball to control the opening of the flow pathways and direct fluid to the second flow path and operate the cutting mechanism (18). Fluid flow through the first pathway can be used to actuate a hydraulically operated tool mounted on the tool string below the cutting tool (10).

Claims

1. A downhole cutting tool comprising: a mandrel, the mandrel having a central mandrel bore with a first end configured to be coupled to an upper tool string, and a first set of ports at a second end; a tool body, the tool body comprising a cutting mechanism having a plurality of knives to cut casing, and having a first end surrounding a portion of the mandrel and a second end configured to be coupled to a lower tool string; a piston axially moveable in a chamber of the tool body and comprising a piston sleeve with a shoulder configured to engage a pivot arm of the cutting mechanism, a piston inlet nozzle to a central piston bore and ports extending into the central piston bore; a first flow pathway through the tool body; a second flow pathway through the tool body; the downhole cutting tool being switchable between a first position and a second position, wherein: in the first position: the first flow pathway is open, and fluid flow from the upper tool string enters the central mandrel bore, passes through the first set of ports into a bypass channel to enter the ports extending into the central piston bore and to an inner bore of the lower tool string, and the knives are retracted and held in a storage position; and in the second position: the second flow pathway is open, the first flow pathway is closed as the bypass channel is closed, and fluid flow from the upper tool string enters the central mandrel bore, passes into the chamber to enter the inlet nozzle to the central piston bore and move the piston sleeve to engage the shoulder with the pivot arm to rotate the knives to an extended operational position to cut casing.

2. The downhole cutting tool according to claim 1 wherein the downhole cutting tool includes shear screws to hold the mandrel relative to the tool body in the first position and weight is set down to move the mandrel relative to the tool body to the second position.

3. The downhole cutting tool according to claim 1 wherein the downhole cutting tool includes a drop ball seat at the second end of the mandrel and a drop ball is used to move the mandrel relative to the tool body to the second position.

4. The downhole cutting tool claim 1 wherein the downhole cutting tool further comprises a third flow pathway configured to direct at least some fluid flow into an annular space around the tool.

5. The downhole cutting tool according to claim 4 wherein the third flow pathway is via a second set of ports, at the second end of the mandrel axially spaced from the first set of ports, and further ports on the tool body.

6. The downhole cutting tool according to claim 5 wherein the downhole cutting tool further comprises a port valve, the port valve blocking the second set of ports when the downhole cutting tool is in the second position.

7. The downhole cutting tool according to claim 1 wherein the downhole cutting tool further comprises spring activated keys located on an internal surface of the tool body which engage with grooves located on an outer surface of the mandrel to hold the mandrel in the first position.

8. The downhole cutting tool according to claim 1 wherein the downhole cutting tool includes a drop ball seat at the second end of the mandrel between the first set of ports and a second set of ports with the second set of ports having channels to direct fluid passed the first set of ports to the channel at the second end of the mandrel so that a drop ball will switch the downhole cutting tool between the first and second positions.

9. The downhole cutting tool according to claim 1 wherein the downhole cutting tool further comprises biasing means to bias the piston in the first position and the biasing means is selected from a group comprising: spring, compression spring, compressible member and resilient member.

10. The downhole cutting tool according to claim 1 wherein the cutting mechanism further comprises a flow restriction assembly axially moveable in the tool body and located in the chamber between the second end of the mandrel and the piston.

11. The downhole cutting tool according to claim 10 wherein the flow restriction assembly comprises an inlet nozzle, a bore and an outlet wherein the outlet is configured to seat in the piston inlet nozzle.

12. The downhole cutting tool according to claim 11 wherein the inlet nozzle is smaller than the piston inlet nozzle.

13. The downhole cutting tool according claim 1 wherein the tool body has a spline so as to transfer torque through the downhole cutting tool in the first and second mandrel positions.

14. The downhole cutting tool according to claim 1 wherein the downhole cutting tool comprises a tool string coupled to the downhole cutting tool as the upper tool string and the lower tool string and wherein a hydraulically actuated downhole tool is coupled to the lower tool string.

15. The downhole cutting tool according to claim 14 wherein the hydraulically actuated downhole tool is selected from a group comprising: drill, mill, packer, bridge plug, hydraulic disconnects, whipstock, hydraulic setting tools and perforating gun.

16. A method of operating a downhole cutting tool and a hydraulically actuated downhole tool on a single downhole trip comprising: providing a downhole cutting tool according to claim 1 wherein the downhole cutting tool comprises a tool string coupled to the downhole cutting tool as the upper tool string and the lower tool string and wherein a hydraulically actuated downhole tool is coupled to the lower tool string; running the tool string into casing with the downhole cutting tool in the first position; pumping fluid through the downhole cutting tool via the first flow pathway to actuate the hydraulically actuated downhole tool; switching the downhole cutting tool to the second position; pumping fluid through the downhole cutting tool via the second flow pathway to extend the knives and thereby cut the casing.

17. The method of operating a downhole cutting tool and a hydraulically actuated downhole tool on a single downhole trip according to claim 16 wherein the method comprises setting weight down on the downhole cutting tool to switch it to the second position.

18. The method of operating a downhole cutting tool and a hydraulically actuated downhole tool on a single downhole trip according to claim 16 wherein the method comprises dropping a ball through the tool string to switch the downhole cutting tool to the second position.

19. The method of operating a downhole cutting tool and a hydraulically actuated downhole tool on a single downhole trip according to claim 16 wherein the method comprises rotating the downhole cutting tool by rotating the tool string whilst the knives are deployed to cut the casing.

20. The method of operating a downhole cutting tool according to claim 16 wherein the hydraulically actuated downhole tool is a drill and actuation of the drill is used to dress-off a cement plug prior to cutting the casing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) There will now be described, by way of example only, various embodiments of the invention with reference to the drawings, of which:

(2) FIG. 1A is a longitudinal sectional view through the downhole tool in first operational mode according to a first embodiment of the invention

(3) FIG. 1B is an enlarged view of a section of the downhole tool of FIG. 1A;

(4) FIG. 1C is an enlarged view of the piston of the embodiment of FIG. 1A;

(5) FIG. 1D is an enlarged view of the pivot arm of the embodiment of FIG. 1A

(6) FIG. 2A is a longitudinal sectional view through the downhole tool in a second operational mode according to an embodiment of the invention;

(7) FIG. 2B is an enlarged view of a section of the downhole tool of FIG. 2A;

(8) FIG. 3A is a longitudinal sectional view through the downhole tool in a cutting mode according to an embodiment of the invention;

(9) FIG. 3B is an enlarged view of a section of the downhole tool of FIG. 3A;

(10) FIG. 4 is a longitudinal view of the downhole tool of FIG. 1A according to an embodiment of the invention.

(11) FIG. 5A is a sectional view of a downhole tool in first operational mode according to an embodiment of the invention.

(12) FIG. 5B is an enlarged view of a section of the downhole tool of FIG. 5A;

(13) FIG. 6A is a longitudinal sectional view through of the downhole tool of 5A in a cutting mode according to an embodiment of the invention;

(14) FIG. 6B is an enlarged view of a section of the downhole tool of FIG. 6A;

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(15) FIGS. 1A, 2A and 3A are longitudinal sectional views of a downhole tool in accordance with a first embodiment of the invention in different phases of operation.

(16) FIG. 1A is a longitudinal section through the downhole tool 10. The downhole tool 10 has an elongate body 12 and a mandrel 14.

(17) A first end 14a of the mandrel 14 is configured to be coupled to an upper tool string such as a drill string (not shown). The second end 14b of the mandrel is axially movably mounted in the body 12.

(18) A first end 12a of the body 12 surrounds a portion of mandrel 14. The second end 12b of the body is configured to be coupled to a lower tool string such as a drill string (not shown). The lower tool string may be connected to downhole tool located further downhole. The second end 12b of the body is designed for insertion into a downhole tubular first.

(19) The mandrel 14 is configured to be axially moveable in the body and is held in a first position by sheer screws 16. The tool body 12 comprises a cutting mechanism 18 configured to deploy knifes 20 to cut the casing.

(20) FIG. 1B shows an enlarged view of area A-A of FIG. 1A. As shown in FIG. 1A the cutting mechanism 18 comprises a plurality of knives 20 disposed circumferentially around the tool body 12. (One knife 20 is shown in FIGS. 1A and 1B). The knives 20 are rotatably mounted on pivot 22, best shown in FIG. 1D, and are configured to move between a storage position where the knives are retracted shown in FIG. 1A and an operational position where the knives are deployed shown in FIGS. 3A and 3B.

(21) The mandrel 14 has a central bore 30 which is closed at the second end 14b. At the second end 14b of the mandrel are located a first set of ports 32 and second set of ports 34. The first and second sets of ports are axially separated from one another. Ports 32 are in fluid communication with channels 32a in the mandrel 14.

(22) FIGS. 1B and 10 shows a piston 40 which is axially movably mounted in the body 12. The piston 40 is configured to move axially between a first position shown in FIG. 1A and second position shown in FIG. 3A. Although it is shown to move between a first and second position, intermediate positions may be selected. The piston 40 comprises a piston sleeve 42. The piston sleeve 42 has a first shoulder 44. Side 44a of shoulder 44 is configured to engage a pivot arm 28 connected to the cutting knives 20, best shown in FIG. 1D. In the first mandrel position the position of the first shoulder 44 hinders the rotation of the pivot arm 28 and maintains the knives in a retracted position.

(23) The piston 40 has an inlet nozzle 50 to a central bore 52 which extends through the piston 40. Ports 54 extend into the central bore 52 of the piston.

(24) The shoulder 44 is configured to minimize the maximum cutting OD (sweep) of the knives when cutting. Side 44b of shoulder 44 is configured to stop the piston 40 at a set cutting OD (Sweep). The side 44b of shoulder 44 may be configured to stop the piston 40 by engaging with a shoulder 47 on the tool body at a set cutting outer diameter sweep. The maximum cutting OD may be adjusted. The maximum cutting OD may be adjusted by changing the position of the sleeve 42 on the piston 40. The sleeve is threaded attached to the piston 40 and the maximum cutting OD can be adjusted by rotating the sleeve. The sleeve position is secured in position by set screws 58. Alternatively, or additionally a screw may be provided that limits the amount the sleeve can be adjusted (not shown).

(25) The piston 40 comprises a shoulder 60. Shoulder 60 is configured to engage the pivot arm 28 connected to the cutting knives 20 and to pivotally move the knives 20 between a knife storage position shown in FIG. 1A and an operational position shown in FIG. 3A when a fluid pressure is applied to piston 40.

(26) The mandrel 14 is held in a first position relative to the body 12 by shear screws 16. The mandrel is configured to move from the first position shown in FIG. 1A to a second position shown in FIG. 2A.

(27) In the first mandrel position a first fluid flow pathway through the tool is open. The first pathway consists of channels 32a on the mandrel 14 in fluid communication with a bypass channel 38. The bypass channel 38 is in fluid communication with ports 54 on the piston 40.

(28) In a first mandrel position the ports 32 align with ports 33 and on the tool body. Fluid that flows through ports 32 and 33 flows into the annular space which may aid in the removal of cutting and/or debris from cutting and/or drill sites.

(29) During normal circulation mode, fluid flows through a first flow pathway in the tool and may actuate and/or control another tool located further downhole on the tool string.

(30) Fluid flowing through the upper tool string first flows through the first flow pathway then through bore 30 of the mandrel. Fluid flows through bore 30 through channels 32a into the bypass channel 38. The flow continues through ports 54 on the piston 40 into the bore 52. The fluid flows in the inner bore of the tool string and may be used to actuate at least one downstream hydraulic tool such as a drill, packer or bridge plug (not shown). Some fluid flows through ports 32 and 33 into the annular space.

(31) In the first mandrel position the ports 34 are blocked by port valve 35 which prevents flow from acting on the piston sleeve to actuate the cutter mechanism 18.

(32) In the first mandrel position, the tool 10 can be rotated on the work string and fluid may be pumped through this first pathway without actuating the cutting mechanism and deploying the knives. This may facilitate the actuation of a downstream tool to enable multiple tasks to be performed in once the tool is deployed downhole without requiring the tool to return to surface.

(33) Flow through the tool may control the actuation of a downstream tool such as a drill or mill and may enable cement dressing off of a cement plug prior to the casing being cut by the cutting mechanism.

(34) By proving a first pathway which bypasses the actuating of the cutting mechanism in the first mandrel position the tool may allow a high fluid flow rate to be pumped through the tool. The tool may also allow the transfer torque to a downstream tool such as a drill bit or mill without actuating the cutting mechanism. FIG. 4 shows a longitudinal view of the tool in circulation mode.

(35) In order to move the mandrel from a first position to a second position an axial load is applied to the mandrel 14. The axial load may be provided by a set down weight or hydraulic pressure. In this example the axial load is provided by a set-down weight which moves the mandrel from the first axial position shown in FIG. 1A to a second axial position shown in FIG. 2A.

(36) The mandrel 14 is configured to be moved within the body 12 to a second position as shown in FIGS. 2A and 2B. The mandrel is held in the second position by spring activated keys 19 located in an internal surface of body 12 engaging with grooves 19a located on the outer surface of the mandrel.

(37) FIGS. 2A and 2B show the mandrel in the second position where the mandrel 14 closes the first pathway and opens a second pathway. The mandrel 14 is moved axially such that ports 32 are not aligned with ports 33 on the body preventing fluid flow from the bore 30 into the annular space. The channels 32a are blocked by port valve 35 and are no longer in fluid communication with the bypass channel 38. The ports 34 on the second end 14b of the mandrel are moved through port valve 35 into chamber 62 in the body 12.

(38) The piston 40 is biased in a direction X by spring 64 as shown in FIG. 2A. In this example the spring 64 is a compression spring. However, it will be appreciated that any spring, compressible member or resilient member may be used to bias the sleeve in a first position.

(39) The spring force acting on the piston provided by spring 64 in direction X maintains shoulder 44 in contact with pivot arm 28 and prevents pivot arm 28 from rotating and deploying the knives 20.

(40) FIGS. 3A and 3B show the actuation of the cutting mechanism when the mandrel in is the second position. Fluid is pumped into the tool string and flows through the second pathway to actuate the cutting mechanism.

(41) Fluid passes through the second pathway. Fluid flows through bore 30 of the mandrel into the chamber 62 via ports 34 on the mandrel 14. The chamber 62 is in fluid communication with an axially moveable restrictor assembly 66. The flow resistor assembly 66 has an inlet nozzle 68, a bore 70 and an outlet 72. The inlet nozzle 68 is configured to introduce a pressure difference in the fluid upstream of the inlet nozzle 68 and the fluid downstream of the inlet nozzle 68.

(42) The fluid flows through the nozzle 68 of the flow restrictor assembly 66. The nozzle 68 is dimensioned to provide a resistance to flow. When the fluid pressure applied to the nozzle 68 it moves the flow resistor assembly 66 in direction Y as shown in FIG. 3A. The outlet 72 of flow restrictor assembly 66 is aligned and/or seated on inlet nozzle 50. When the fluid pressure applied to the nozzle 68 is sufficient to overcome the spring force of spring 64 the flow restrictor assembly 66 and piston 40 are moved towards second end 12b of the downhole tool, shown as direction Y in FIG. 3A.

(43) The flow resistor assembly 66 may be adjusted to stop at selected position after travelling a predetermined distance in direction Y. When the flow resistor assembly 66 stops at this selected position the outlet 72 of flow restrictor assembly 66 will not be aligned and/or seated in inlet nozzle 50. Flow will bypass the smaller nozzle 68, and will flow through the larger sleeve inlet nozzle 50. This may provide a pressure change when the knives are at a certain cutting OD (sweep) and provide an indication that the knives are deployed and/or the cut has been made.

(44) Movement of the piston 40 and sleeve 42 in direction Y axially moves shoulder 60 to engage and move pivot arm 28 connected to the cutting knives 20. The knives 20 are moved to an operational position to allow the cutting of a casing shown in FIG. 3A.

(45) The pivot arm 28 has a slot 29 (best shown in FIG. 1D) which prevents the pivot arm impacting the sleeve when the knife is rotated to an extended position.

(46) To retract the knives 20, the fluid flow through the second pathway is reduced. The fluid pressure applied to nozzle 68 and/or nozzle 50 is no longer sufficient to overcome the spring force of spring 64 and the flow restrictor assembly 66, piston 40 and sleeve 42 are moved towards first end 12a of the downhole tool, shown as direction X in FIG. 3A.

(47) The movement of the piston 40 in direction X moves the shoulder 60 to disengage with the pivot arm 28. Shoulder 44 engages with the pivot arm 28 which rotates pivot arm 28 and retract the knives 20.

(48) The fluid pumped through the second pathway may be adjusted to control the degree of deployment of the knives 20.

(49) The tool and/or tool string may be rotated with the knives deployed to cut the tubular. The tool can be rotated when the knifes are in an operational or retracted position. The tool has a spline that transfer the torque in both positions.

(50) The tool described above may be provided with a plurality of seals. Seals may be provided along the first and/or second pathway to prevent fluid egress. Seals may be provided between the mandrel and the tool body.

(51) The above example described the switching between a first mandrel position and a second mandrel position by applying an axial force in the form of a set-down weight. However, an alternative method applying an axial force is a ball-drop.

(52) FIGS. 5A, 5B, 6A and 6B show an alternative design for downhole tool 110. The tool comprises a ball seat 180 at end 114b of mandrel 114. The ball seat 180 has first series of ports 182 and a second series of ports 184 (shown best in FIG. 5B). The first series of ports 182 are aligned with the first pathway. The first fluid pathway is similar to the first fluid pathway described in relation to FIGS. 1A and 1B and will be understood from the description of FIGS. 1A and 1B above.

(53) During normal circulation mode, the first fluid flow pathway through the tool is open. The first pathway consists of first series of ports 182 on the ball seat 180 which are in fluid communication with a bypass channel 138. The bypass channel 138 is in fluid communication with ports 154 on the piston 140.

(54) Fluid flows through the first flow pathway and may actuate and/or control a hydraulically operated tool located further downhole on the tool string.

(55) Some flow may pass through the second series of ports 184 in the ball seat and into the second flow path. The second flow path is similar to the second fluid pathway described in relation to FIGS. 2A and 2B and will be understood from the description of FIGS. 2A and 2B above. The second fluid pathway consists of series of ports 184 on the ball seat 180 which are in fluid communication with chamber 162. The chamber 162 is in fluid communication with the cutting mechanism 118. However, during normal circulation mode the flow through the second flow path is not sufficient to actuate the cutting mechanism 118.

(56) FIGS. 6A and 6B show actuation of the cutting mechanism. To actuate the cutting mechanism 118 a ball 190 is dropped in the bore of the tool string and is carried by fluid flow through bore 130 until it is retained by the ball seat 180. Once the ball 190 has engaged the ball seat 180 the ball 190 blocks ports 182 preventing fluid flow in the first pathway. Fluid is directed though ports 184 into the chamber 162 and through the second pathway. The actuation of the cutting mechanism is as described in relation to FIGS. 3A and 3B and will be understood from the description of FIGS. 3A and 3B.

(57) In this example the mandrel is not axially moveable between a first and second position. In this case the first series of ports 182 are always aligned with the first pathway and the second series of ports 184 are always aligned with the second pathway.

(58) Alternatively, and/or additionally, the mandrel and/or ball seat may be axially movable in the tool body. The mandrel and/or ball seat may be axially moveable when sufficient fluid pressure is applied to the ball and ball seat providing an axial force on the mandrel to move it to a second position. The mandrel and/or ball seat when moved to the second position the second series of ports are aligned with the second pathway.

(59) During normal circulation mode, fluid flows through the bore of the mandrel. The flow passes through the first flow pathway via the series of ports and may actuate and/or control a hydraulically operated tool located further downhole on the tool string.

(60) To actuate the cutting mechanism a ball is dropped in the bore of the tool string and is carried by fluid flow where its retained by the ball seat. Once the ball has engaged the ball seat it blocks the first series of ports preventing fluid flow in the first flow pathway. The fluid pressure may act on the ball seat and when sufficient fluid pressure acts on the ball seat the mandrel and/or ball seat be axially movable to a second position in the tool body. The mandrel and/or ball seat in the second position uncovers a second series or ports which are in fluid communication with the second fluid path way. Subsequent fluid flow through the second fluid flow pathway actuates the cutting mechanism disposed in the second fluid flow pathway.

(61) Throughout the specification, unless the context demands otherwise, the terms comprise or include, or variations such as comprises or comprising, includes or including will be understood to imply the inclusion of a stated integer or group of integers, but not the exclusion of any other integer or group of integers. Furthermore, relative terms such as, lower, upper, up down and the like are used herein to indicate directions and locations as they apply to the appended drawings and will not be construed as limiting the invention and features thereof to particular arrangements or orientations. Likewise, the term inlet shall be construed as being an opening which, dependent on the direction of the movement of a fluid may also serve as an outlet, and vice versa.

(62) The invention provides a downhole cutting tool. The tool comprises a tool body, a first flow pathway and a second flow pathway through the tool body. The tool also comprises a cutting mechanism configured to be in fluid communication with the second fluid flow pathway and a switching mechanism configured operable to control the opening of the first and/or second fluid flow pathway.

(63) The present invention obviates or at least mitigates disadvantages of prior art downhole tools and provides a robust, reliable and compact downhole cutting tool suitable for actuating multiple downhole tool and cutting a casing in a single trip.

(64) The invention enables multiple downhole operations to be performed on the same downhole trip, which normally would require at least two separate trips. The invention allows sufficient fluid flow to be pumped through the tool to actuate tools on the tool strings further downhole without uncontrolled actuation of the cutting tool.

(65) The invention allows the selective actuation of different tools on the same tools string. This may facilitate the controlled actuation of downhole tools such as drills and mills which require high flow rates on the same tool string as a casing cutter tool which requires a lower fluid flow rate.

(66) This may facilitate the actuation of a drill to dress-off a cement plug and the subsequent activation of the cutting tool to cut the casing in a single downhole trip. The invention avoids the simultaneous and/or accidental actuation of the downhole tools on the tool string. The downhole cutting tool has improved productivity and efficiency, and is capable of reliably performing multiple downhole operations once deployed downhole.

(67) The foregoing description of the invention has been presented for the purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the precise form disclosed. The described embodiments were chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilise the invention in various embodiments and with various modifications as are suited to the particular use contemplated. Therefore, further modifications or improvements may be incorporated without departing from the scope of the invention herein intended.