Hydraulic Disconnect Apparatus and Method of Use
A hydraulic disconnect apparatus is disclosed for disconnecting a pipe string or coiled tubing string from a bottom hole assembly for drilling, work over, or plug and abandonment of oil and gas wells. Disconnection is accomplished by pumping a circulation ball from surface through the pipe or coiled tubing string until it lands on a seat inside the apparatus. Fluid pressure is then applied to shift a piston assembly within the apparatus, thereby allowing a series of balls to retract. The upper and lower portions of the apparatus can then be separated by applying a tensile force to the upper portion.
This application claims priority to U.S. provisional application Ser. No. 61/695,710 filed Aug. 31, 2012 for Hydraulic Disconnect Apparatus and Method, the entire content of which is hereby incorporated by reference.
FIELD OF THE INVENTIONThis invention pertains to downhole equipment for oil and gas wells. More particularly, it pertains to a hydraulic disconnect apparatus for use on a wellbore pipe string such as a coiled tubing string and, more particularly, this invention relates to an apparatus for disconnecting a pipe string from a bottom hole assembly (known as a BHA).
BACKGROUND OF THE INVENTIONDuring the drilling, work over, or plug and abandonment of oil and gas producing wellbores, a variety of downhole tools can be attached to a pipe or coiled tubing string and utilized to perform a variety of functions within the wellbore. It is often desirable to disconnect a tool from the pipe or coiled tubing string so that a tool may be left in the wellbore when the pipe or coiled tubing string is removed. Other times, a tool may become stuck in the wellbore during wellbore operations and the need arises to remove the pipe or coiled tubing string from the wellbore, independent of the tool, so that the wellbore may be reentered with a fishing tool string in an attempt to free the stuck tool from the wellbore. For these reasons, a tool disconnect device must be utilized.
A variety of tool disconnect devices may be use. Many tool disconnect devices employ a hydraulic tool disconnect mechanism that employ shear pins and collets in the disconnect mechanism. These tools suffer from shortcomings ranging from premature shear pin failure to cracking of collet bodies induced by the assembly or disassembly process. Some hydraulic disconnect devices employ a piston or ball to effectuate pressure changes for disconnection and that ball is typically left in the bottom sub portion of the hydraulic disconnect after the tool is disconnected from the pipe or coiled tubing string. A ball left in the bottom sub may prevent an operator from subsequently circulating fluid through the bottom sub and hinder subsequent well operations. Other types of tool disconnect devices suffer from unreliable tool disconnection or require high pressures in order to disconnect a tool from the pipe or coiled tubing string.
Consequently, there is a need for a hydraulic tool disconnecting apparatus having improved piston and collet configurations that will reliably disconnect a tool or BHA from a pipe or coiled tubing string without the aforementioned negative attributes.
SUMMARY OF THE INVENTIONThe present invention presents a new hydraulic disconnect apparatus to satisfy the aforementioned needs. The disconnect apparatus is comprised of an upper top sub member having a plurality of ball retaining pockets, a lower bottom sub housing member and a piston member preferably comprised of two parts, and a plurality of balls. The piston member is preferably configured with a lower support piston member and an upper collet member. The bottom sub contains a plurality of internal indentations that correspond with the balls, preferably matching or nearly matching the radii of the balls. The collet member contains an internal profile such that a circulation ball of a given size will seat and substantially block the circulation of fluid through the disconnect apparatus.
In the configurations shown in
Positioned within the top sub (5) and bottom sub (15) are a support piston (55) and a collet (50). The support piston (55) and coil t (50) are threadably connected by means of box connection (70) of collet. (50) and pin connection (180) of support piston (55). Support piston (55) and collet (50) are axially aligned with top sub (5) and bottom sub (15). The annulus between collet (50) and the internal surface of top sub (5) is sealed b means of seal (80). The annulus between support piston (55) and the internal bore of bottom sub (15) is sealed via by means of seal(s) (95). The combination of the support piston (55) and collet (50) will sometimes be referred to as piston assembly (200), as shown in
A plurality of attachment balls (60) arrayed in a series are located in ball retaining pockets (150) along top sub (5). These balls (60) are urged radially outward by contact with the support piston (55) to extend or protrude from retaining pockets (150) into indentations or dimples (90) in bottom sub (15). The balls (60) prevent the top sub (5) from moving in both axial and circumferential directions in relation to the bottom sub (15). Thus the balls (60) prevent the top sub (5) from separating from the bottom sub (15) due to tensile forces. The balls (60) also aid in the transmission of torque from the top sub (5) to the bottom sub (15) or vice versa.
The support piston (55) is configured with a shoulder (125) which abuts the lower face (195) of top sub (5). The support piston (55) may be secured in this position via shear screw(s) (100) and by collet (50). Collet (50) can also be configured such that shear screw(s) (100) may be eliminated completely. Surface (110) of collet (50) is in contact with abutment surface (105) of top sub (5). Collet (50) holds the support piston (55) in the correct location to keep the balls (60) firmly pressed into dimples (90) in bottom sub (15), thereby keeping apparatus (10) in a connected configuration.
The top sub (5) of the hydraulic disconnect apparatus (10) is shown in
The top sub (5) of apparatus (10) is not provided with and does not require a sub collet for load transfer. The collet (50) in disconnect apparatus (10) simply retains the piston assembly (200) in place so as not to rely on shear screws as is the case with many current hydraulic disconnect devices. Collets are necessarily utilized in the subs in many current hydraulic disconnect devices to serve as tensile load bearing components. When a tensile load is applied to a pipe string or coiled tubing string configured with these disconnect devices, the tensile load applied must be transferred through the collet members of the sub. Accordingly, the collets of such devices are subjected to repeated tensile loads placed upon them during in normal wellbore operations, such as when the pipe string is jarred, and these repeated loads increase wear and tear on these disconnect devices and the risk of premature separation. Because the hydraulic disconnect apparatus (10) described herein does not utilize a collet as a load bearing member, the pipe string and the apparatus (10) may be repeatedly jarred during operations with the risk of premature separation of the BHA from the pipe string due to connection failure, such as shearing of the shear pin (or screw), significantly reduced.
The support piston (55) of the hydraulic disconnect apparatus (10) is shown in
In the typical hydraulic disconnect device only shear screws are employed to retain a piston assembly in place. Use of the collet (50) gives the hydraulic disconnect apparatus (10) the ability to withstand repeated jarring impacts without the potential for premature separation of the BHA. Another advantage of the collet (50) of disconnect apparatus (10) is that collet (50) does not have to be collapsed for assembly and disassembly of the apparatus (10). Most hydraulic disconnect devices utilize collets where the fingers of the collets must be collapsed in order for the tool to be assembled and disassembled. Stresses are induced into a collet each time it is collapsed and this repeated collapsing can cause cracking in the fingers of the collet leading to premature failure.
For assembly of the hydraulic disconnect apparatus (10), the balls (60) are first inserted into the ball retaining pockets (150) of top sub (5) until balls (60) contact pocket protrusions (155). After all balls (60) are in place, the support piston (55) is inserted into the lower end of top sub (5) with the ball recesses (85) aligned with the balls (60). Insertion continues until shoulder (125) abuts lower face (195). Collet (50) is then inserted into top sub (5) and box connection (70) is partially threadably engaged to pin connection (180). The support piston (55) must be repositioned downward such that the balls (60) are fully retracted. The top sub (5) along with the partially threaded piston assembly (200) is then inserted into bottom sub (15) while interlocking castle features (30) and (35) until it can go no further.
The piston assembly (200) is then shifted upward until shoulder (125) again abuts lower face (195). When the piston assembly (200) is shifted upward the balls (60) will be pushed radially outward from the ball recesses (85) and seated in the dimples (90) that are located inside the bottom sub (15). The collet (50) is then fully threaded to support piston (55) until tight. The shear screws (100) can now be inserted if being utilized. The hydraulic, disconnect apparatus (10) is now complete.
As shown in
As shown in
When a tensile load, is applied to the pipe string, the top sub (5) of the hydraulic disconnect apparatus (10) is separated from the bottom sub (5) as shown in
Claims
1. A disconnect apparatus for disconnecting a pipe string from a bottom hole assembly comprising:
- (a) a tubular top sub member having an upper end, a lower end, a central bore through which a fluid may be introduced, a collet engagement surface, a plurality of radially oriented ball retaining pockets, and an internal abutment shoulder;
- (b) a plurality of attachment balls extending from said ball retaining pockets of said top sub member;
- (c) a support piston assembly having an upper end, a lower end, a central bore through which a fluid may be introduced, a collet section at said upper end, said collet section having an external abutment shoulder, and a piston section at said lower end, said piston section having a plurality of ball recesses;
- (d) said support piston assembly positioned within and releasably attached to said top sub member by means of said collet section and said collet engagement surface and configured to move upward and downward within said top sub member upon release of said collet from said collet engagement surface of said top sub member, said downward support piston assembly movement being restrained by said internal abutment shoulder of said top sub member and said external abutment shoulder of said collet;
- (e) a tubular bottom sub member having an upper end, a lower end, a central bore through which a fluid may be introduced, and a plurality of internal radially oriented dimples, said bottom sub member attached to said top sub member by engagement of said attachment balls within said internal dimples of said bottom member between said piston section and said bottom sub member; and
- (f) wherein downward movement of said support piston assembly will move said attachment balls from said internal dimples of said bottom sub member into said ball recesses of said piston section thereby releasing said bottom sub member from said top sub member.
2. The disconnect apparatus recited in claim 1 wherein said upper end of said top sub member is attached to a pipe string and said lower end of said bottom sub member is attached to a bottom hole assembly.
3. The disconnect apparatus recited in claim 2 wherein the introduction of a desired pressure on said support piston assembly will release said collet section of said piston support assembly from said collet engagement surface of said top sub member thereby imparting downward movement of said piston support assembly for releasing said bottom sub member.
4. The disconnect apparatus recited in claim 3 wherein said desired pressure on said on said support piston assembly is created by a circulation ball obstructing said central bore of said support piston assembly.
5. The disconnect apparatus recited in claim 4 wherein said top sub member and said bottom sub member abut between interlocking splines.
6. A disconnect apparatus for disconnecting a pipe string from a bottom hole assembly comprising:
- (a) a pipe string having central bore through which a fluid may be introduced;
- (b) a tubular top sub member having an upper end, a lower end, and a central bore aligned with said central bore of said pipe string through which a fluid may be introduced, said upper end of said top sub member threadedly attached to said pipe string;
- (c) said top sub member having a collet engagement surface and a plurality of radially oriented ball retaining pockets;
- (d) a plurality of attachment balls positioned in said ball retaining pockets of said top sub member;
- (e) a support piston assembly positioned within said top sub member, said support piston assembly having a central bore aligned with said central bore of said top sub member, a collet section releaseably attached to said collet engagement surface of said top sub member, and piston section having a plurality of plurality of ball recesses, said support piston assembly and said top sub member configured to limit axial travel of said support piston assembly within said top sub member upon release of said collet from said collet engagement surface of said top sub member; and
- (f) a tubular bottom sub member having a plurality of internal radially oriented dimples and a central bore through which a fluid may be introduced, said bottom sub member attached to said top sub member by confined engagement of said attachment balls between said internal dimples of said bottom sub member and said piston member wherein upon release of said collet from said collet engagement surface of said top sub member, said attachment balls will disengage from said internal dimples of said bottom sub member and move into said ball recesses of said piston section thereby releasing said bottom sub member from said top sub member.
7. The disconnect apparatus recited in claim 6 wherein said bottom sub member is attached to a bottom hole assembly.
8. The disconnect apparatus recited in claim 7 wherein a desired pressure on said support piston assembly will release said collet section of said piston support assembly from said collet engagement surface of said top sub member.
9. The disconnect apparatus recited in claim 8 wherein said desired pressure on said on said support piston assembly is created by introduction of a circulation ball into said central opening of said pipe string thereby obstructing said central bore of said support piston assembly.
10. The disconnect apparatus recited in claim 8 wherein said top sub member and said bottom sub member abut between interlocking splines.
11. In a pipe string having a having a central bore containing a fluid column, a method for disconnecting a pipe string from a bottom hole assembly comprising the steps of:
- (a) providing a pipe string having a central bore containing to fluid column;
- (b) providing a tubular top sub member having an upper end, a lower end, and a central bore aligned with said central bore of said pipe string, said top sub member having a collet engagement surface and a plurality of radially oriented ball retaining pockets;
- (c) providing a plurality of attachment balls positioned in said ball retaining pockets of said to sub member;
- (d) providing a support piston assembly, said support piston assembly having a central bore aligned with said central bore of said top sub member, a collect section, and piston section having a plurality of plurality of ball recesses;
- (e) positioning said support piston assembly within said top sub member in a manner whereby axial travel of said support piston assembly within said top sub member is limited;
- (f) releasably attaching said collet section of said piston support assembly to said collet engagement surface of said top sub member;
- (g) providing a bottom sub member having a plurality of internal radially oriented dimples and a central bore through which a fluid may be introduced;
- (h) attaching said top sub member to said bottom sub member in a manner whereby said attachment balls are confined between said internal dimples of said bottom sub member and said piston member and whereby upon release of said collet from said collet engagement surface of said top sub member, said attachment balls will disengage from said internal dimples of said bottom sub member and move into said ball recesses of said piston section thereby allowing said bottom sub member to be released from said top sub member;
- (i) attaching said bottom sub member to a bottom hole assembly;
- (j) running said pipe string and said attached bottom hole assembly into a wellbore; and
- (k) releasing said collet from said collet engagement surface of said top sub member thereby moving said support piston assembly and said attachment balls from said internal dimples of said bottom sub member into said ball recesses of said piston section of support piston assembly thereby releasing said bottom sub member from said top sub member.
12. The method as recited in claim 11 further comprising the step of applying tension to said pipe string.
13. The method as recited in claim 12 wherein said step of releasing said collet from said collet engagement surface of said top sub member includes the step of apply fluid pressure on said support piston assembly.
14. The method as recited in claim 13 wherein the step of apply fluid pressure on said support piston assembly includes introducing a circulation ball into said central opening of said pipe string thereby obstructing said central bore of said support piston assembly.
15. The method as recited in claim 14 wherein the step of attaching said top sub member to said bottom sub member includes abutting said top sub member and said bottom sub member between interlocking splines.
16. The method as recited in claim 15 wherein the step of positioning said support piston assembly within said top sub member in a manner whereby axial travel of said support piston assembly within said top sub member is limited includes providing interfacing shoulder surfaces on said top sub member and said collet of said support piston assembly.
17. A disconnect apparatus for disconnecting a pipe string from a bottom hole assembly comprising:
- (a) a pipe string having central bore through which a fluid may be introduced;
- (b) a tubular top sub member threadedly attached to said pipe string; said top sub member having a collet engagement surface and a plurality of radially oriented ball retaining pockets;
- (c) a plurality of attachment balls positioned in said ball retaining pockets of said top sub member;
- (d) a support piston assembly haying a collet and a piston section having a plurality of plurality of ball recesses, said support piston assembly releasably attached to said collet engagement surface of said top sub member and positioned within said top sub member to allow limited axial moment of said support piston assembly within said top sub member;
- (e) a tubular bottom sub member having a plurality of internal radially oriented dimples, said bottom sub member abutting said top sub member with said attachment balls confined between said internal dimples of said bottom sub member and said piston member thereby attaching said bottom sub member to said top sub member and whereby downward movement of said support piston assembly will move said attachment balls from said internal dimples of said bottom sub member into said ball recesses of said piston section of support piston assembly thereby releasing said bottom sub member from said top sub member; and
- (f) a bottom hole assembly attached to said bottom sub member.
18. The disconnect apparatus recited in claim 17 further comprising a means for obstructing said central bore of said support piston assembly and creating a desired pressure on said support piston assembly thereby releasing said collet from said collet engagement surface of said top sub member causing downward movement of said support piston assembly.
19. The disconnect apparatus recited in claim 18 wherein axial travel of said support piston assembly within said top sub member is limit by interfacing shoulder surfaces on said top sub member and said collet of said support piston assembly.
20. The disconnect apparatus recited in claim 19 further comprising interlocking splines between said top sub member and said bottom sub member.
Type: Application
Filed: Aug 31, 2013
Publication Date: Mar 6, 2014
Inventor: Toby Scott Baudoin (Rayne, LA)
Application Number: 14/016,097
International Classification: E21B 23/03 (20060101);