Downhole pump apparatus having decoupleable isolation plug

Abstract

A pump apparatus for recovering hydrocarbons from downhole wells, having a seating surface adapted to sealingly engage an interior surface of a circumferential seal member situated within production tubing when said pump is in a downhole operative position. An isolation plug is provided, releasably coupled to a lower end of said pump, having sealing means thereon to sealingly engage said interior surface of said circumferential seal member when the isolation plug is linearly positioned within said circumferential seal member and decoupled from the pump assembly, thereby preventing gases and fluids from fluid communication to surface when the pump is raised and removed from the well. A method for sealing a well upon removal of a pump is further disclosed.

1 . A downhole pump apparatus for preventing gases and fluids within a hydrocarbon formation from having fluid communication to surface upon removal of a downhole pump from within a production well, comprising:
 a pump assembly having a pump means, further having a seating surface adapted to sealingly engage an interior surface of a circumferential seal member situated within production tubing when said pump assembly is in a downhole operative position;   an isolation plug, longitudinally spaced apart from said seating surface on said pump assembly, and releasably coupled to a lower end of said pump assembly, adapted for linear movement within said production tubing, having sealing means thereon dimensioned to sealingly engage said interior surface of said circumferential seal member when said isolation plug is linearly positioned within said circumferential seal member;   releasable latch means situated on said lower end of said pump assembly, adapted for releasably de-coupling said isolation plug from said lower end of said pump assembly when said sealing means on said isolation plug sealingly engages said circumferential sealing member;
 wherein said pump assembly when raised from said downhole operative position is adapted to cease sealing engagement between said circumferential seal member and said seating surface, and said isolation plug when simultaneously raised is adapted for said sealing means thereon to become sealingly engaged with said circumferential seal member, and said latch means may thereafter be operated to disengage said isolation plug and said isolation plug thereby remains downhole when said remainder of said pump apparatus is further raised from within said production well. 
   
     
     
         2 . The downhole pump apparatus as claimed in  claim 1 ,
 wherein said latch assembly thereon, when said pump assembly is lowered downhole, is adapted to engage said isolation plug in said production well and force said isolation plug downwardly out of sealing engagement with said circumferential seal member and allow said seating surface on said pump assembly to then re-engage in sealing relationship said circumferential seal member.   
     
     
         3 . A downhole pump apparatus for preventing a production well from having fluid communication to surface upon removal of a downhole pump from said well, comprising:
 elongate tubing means, having at a distance therealong an interior circumferential seal member;   an isolation plug, having sealing means thereon and dimensioned to permit said sealing means thereon to sealingly engage said interior circumferential seal means when said isolation plug is linearly positioned within said tubing at said distance along an interior of said elongate tubing means;   a downhole pump assembly coupleable to said isolation plug, having at an upper end thereof a seating surface adapted to sealingly engage said circumferential seal member when said pump assembly is in a downhole operative position, and having on a lower mutually opposite end thereof latch member for releasably engaging said isolation plug;   wherein said downhole pump assembly when raised from said downhole operative position is adapted to cease sealing engagement between said interior circumferential seal means and said seating surface, and said isolation plug when simultaneously raised is adapted for said sealing means thereon to become sealingly engaged with said circumferential seal means, and said latch means may thereafter be operated to disengage said isolation plug and said isolation plug thereby remains downhole when said downhole pump assembly is raised; and   wherein said downhole pump assembly when lowered downhole said latch assembly thereon is adapted to engage said isolation plug in said downhole well and force said isolation plug downwardly out of sealing engagement with said circumferential seal means.   
     
     
         4 . The downhole pump apparatus as claimed in  claim 3 , further comprising a stop member within said production tubing proximate a bottom of said production well, against which the isolation plug may abut, to allow said latch means when lowered onto said isolation plug to be forceably coupled to said isolation plug. 
     
     
         5 . A downhole pump apparatus for preventing a production well from having fluid communication to surface upon removal of a downhole pump from said well, comprising:
 elongate tubing means, having at respective distances therealong longitudinally spaced-apart first and second circumferential seal members;   a downhole pump assembly, having a seating surface adapted when said pump assembly is in a downhole operative position to sealingly engage and interior surface of said first circumferential seal member;   an isolation plug, releasably coupleable to a lower end of said downhole pump assembly, having sealing means thereon and dimensioned to permit said sealing means thereon to sealingly engage an interior surface of said said second circumferential seal member when said downhole pump assembly and seating surface is raised thereby disengaging said seating surface from seating engagement with said first circumferential seal member;   latch means, situated on a lower end of said downhole pump assembly opposite said upper end thereof, adapted for releasably coupling said isolation plug to said lower end of said downhole pump assembly;   wherein said downhole pump assembly, when raised from said downhole operative position, is adapted to cease sealing engagement between said first circumferential seal member and said seating surface, and said isolation plug thereon when simultaneously raised is adapted to permit said sealing means thereon to become sealingly engaged with said second circumferential seal member as to prevent fluid communication from a downhole side of said isolation plug to an uphole side of said isolation plug; and   wherein said latch means is adapted to permit said isolation plug when sealingly engaging said second sealing means to become uncoupled from said downhole pump assembly so as to permit said isolation plug to thereby remain downhole when said downhole pump assembly is further raised; and   wherein said downhole pump assembly when lowered downhole is adapted to sealingly re-engage said first circumferential seal member, and said latch assembly thereon is adapted to engage said isolation plug in said downhole well and force said isolation plug downwardly out of sealing engagement with said second circumferential seal member.   
     
     
         6 . A method for removing a downhole pump assembly from a well which avoids undesirable flow of downhole fluids to surface upon removal of said pump assembly, comprising the steps of:
 (a) providing first and second interior circumferential seal means along an elongate tubing means, at respective spaced-apart longitudinal distances therealong;   (b) providing a downhole pump assembly, having at an upper end thereof a seating surface;   (c) providing an isolation plug, releasably coupleable to a lower end of said downhole pump assembly, having sealing means thereon and dimensioned to permit said sealing means thereon to sealingly engage said second interior circumferential seal means when said downhole pump assembly and seating surface is raised thereby disengaging said seating surface from seating engagement with said first circumferential seal;   (d) providing latch means, situated on a lower end of said downhole pump assembly opposite said upper end thereof, adapted for releasably coupling said isolation plug to said lower end of said downhole pump assembly;   (e) lowering said pump assembly in a downhole operative position within said well so as to permit said seating surface thereon to sealingly engage said first circumferential seal means;   (f) raising said downhole pump assembly thereby causing said seating means to cease sealing engagement between said first circumferential seal means and said seating surface, and simultaneously causing said isolation plug thereon to become sealingly engaged with said second circumferential seal means so as to prevent fluid communication from a downhole side of said isolation plug to an uphole side of said isolation plug; and   (g) causing said latch means to releasably uncouple said isolation plug from said downhole pump assembly so as to permit said isolation plug to thereby remain downhole when said downhole pump assembly is further raised and removed from said well.   
     
     
         7 . The method as claimed in  claim 6 , further comprising the steps, after step (g), of:
 lowering said downhole pump assembly within said well so as to permit said seating surface thereon to sealingly re-engage said first circumferential seal means and simultaneously causing said latch assembly thereon to engage said isolation plug in said downhole well; and   forcing said isolation plug downwardly out of sealing engagement with said second circumferential seal means.