Hydraulic Disconnect Apparatus and Method of Use

Abstract

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.

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.