Unloader valve assembly

Abstract

An unloader valve assembly includes a cylindrical housing defining an annular space, an inner wall thereof including a port that enables fluid communication between the annular space and a location outside the inner wall of the housing. A mandrel having a tubular configuration is positioned inside the housing, the mandrel defining a central bore for receiving fluid and includes a mandrel port enabling fluid communication between the central bore and the annular space. A piston encircling the mandrel is movable along an axis defined by the central bore. A spring is situated between the inner wall of the housing and the mandrel and movable between an extended configuration urging the piston downwardly and a compressed configuration being urged upwardly by the piston.

1 . An unloader valve assembly for engaging, via a seal mandrel assembly, a cement retainer assembly that is deployed inside a casing of a well bore and that is attached to the casing with slips and having a sliding sleeve initially in a closed configuration not allowing fluid to flow into proximity of the cement retainer assembly from a check valve assembly having a flapper at an open configuration, the sliding sleeve being slidably movable to an open configuration upon downward urging of the seal mandrel assembly into engagement with the cement retainer allowing fluid to flow from the check valve assembly into the casing, said unloader valve assembly, comprising:
 a housing that includes an inner wall having a cylindrical configuration defining an annular space;   wherein said inner wall of said housing includes a port that enables fluid flow between said annular space and a location outside said inner wall of said housing;   an upper adapter coupled to an upper end of said housing and operable to engage the check valve assembly;   a lower adapter coupled to a lower end of said housing and operable to engage the seal mandrel assembly;   a mandrel positioned inside said interior space of said housing and inwardly displaced from said inner wall of said housing, said mandrel having a tubular configuration defining a central bore for receiving a flow of fluid;   wherein said mandrel includes a mandrel port operable for fluid communication between said central bore and said annular space;   a piston encircling said mandrel that is movable along an axis defined by said central bore when urged to move;   a spring having an upper end operably coupled to said upper adapter and a lower end operably coupled to said piston, said spring being situated between said inner wall of said housing and said mandrel and movable between an extended configuration urging said piston downwardly and a compressed configuration being urged upwardly by said piston.   
     
     
         2 . The unloader valve assembly as in  claim 1 , wherein said spring is naturally biased toward said extended configuration so as to urge said piston downwardly to bear against said lower adapter. 
     
     
         3 . The unloader valve assembly as in  claim 1 , wherein a volume of said annular space is increased when said piston is urged upwardly in said annular space and said spring is moved toward said compressed configuration. 
     
     
         4 . The unloader valve assembly as in  claim 3 , wherein said annular space has a volume sufficient to contain an entire volume of fluid displaced by penetration of the seal mandrel assembly into the cement retainer assembly. 
     
     
         5 . The unloader valve assembly as in  claim 2 , wherein a pressure increase in said central bore is communicated through said mandrel port and bears against a bottom of said piston so as to urge said piston upwardly to compress said spring toward said compressed configuration. 
     
     
         6 . The unloader valve assembly as in  claim 5 , wherein fluid in said central bore is allowed to flow from said central bore through said port in said inner wall of said housing to said location outside said housing as said piston is urged upwardly. 
     
     
         7 . The unloader valve assembly as in  claim 6 , wherein said piston moves upwardly in unison with fluid being displaced by penetration of the seal mandrel assembly into the cement retainer assembly. 
     
     
         8 . The unloader valve assembly as in  claim 1 , wherein:
 said upper adapter is coupled to said housing in a threaded engagement;   said lower adapter is coupled to said housing in a threaded engagement.   
     
     
         9 . An unloader valve assembly, comprising:
 a housing that includes an inner wall having a cylindrical configuration defining an annular space;   wherein said inner wall of said housing includes a port that enables fluid flow between said annular space and a location outside said inner wall of said housing;   an upper adapter coupled to an upper end of said housing and operable to engage a check valve assembly;   a lower adapter coupled to a lower end of said housing operable to engage a seal mandrel assembly;   a mandrel positioned inside said interior space of said housing and inwardly displaced from said inner wall of said housing, said mandrel having a tubular configuration defining a central bore for receiving a flow of fluid;   wherein said mandrel includes a mandrel port operable for fluid communication between said central bore and said annular space;   a piston encircling said mandrel that is movable along an axis defined by said central bore; and   a spring having an upper end operably coupled to said upper adapter and a lower end operably coupled to said piston, said spring being situated between said inner wall of said housing and said mandrel and movable between an extended configuration urging said piston downwardly and a compressed configuration being urged upwardly by said piston.   
     
     
         10 . The unloader valve assembly as in  claim 9 , wherein said spring is naturally biased toward said extended configuration so as to urge said piston downwardly such that said piston bears against said lower adapter. 
     
     
         11 . The unloader valve assembly as in  claim 9 , wherein a volume of said annular space is increased when said piston is urged upwardly in said annular space and said spring is moved toward said compressed configuration. 
     
     
         12 . The unloader valve assembly as in  claim 9 , wherein a pressure increase in said central bore is communicated through said mandrel port and bears against a bottom of said piston so as to urge said piston upwardly so as to move said spring toward said compressed configuration. 
     
     
         13 . The unloader valve assembly as in  claim 5 , wherein fluid in said central bore is allowed to flow from said central bore through said port in said inner wall of said housing to said location outside said housing as said piston is urged upwardly. 
     
     
         14 . The unloader valve assembly as in  claim 9 , wherein:
 said upper adapter is coupled to said housing in a threaded engagement;   said lower adapter is coupled to said housing in a threaded engagement.   
     
     
         15 . An unloader valve assembly for placement in a casing of a well bore, comprising:
 a seal mandrel assembly situated in the casing;   a check valve assembly having a flapper member positioned in the casing for insertion of a fluid into the casing;   a cement retainer assembly positioned inside the casing lowerly adjacent said seal mandrel assembly and coupled to a wall thereof with slips and having a sliding sleeve initially in a closed configuration not allowing fluid to flow into proximity of the cement retainer from said check valve when said flapper is at an open configuration, said sliding sleeve being slidably movable to an open configuration upon downward urging of said seal mandrel assembly into engagement with said cement retainer assembly allowing fluid to flow from the check valve assembly into the casing;   a housing situated within the casing between said check valve assembly and said seal mandrel assembly and that includes an inner wall having a cylindrical configuration defining an annular space;   wherein said inner wall of said housing includes a port that enables fluid flow between said annular space and a location outside said inner wall of said housing;   an upper adapter coupled to an upper end of said housing and operable to engage said check valve assembly;   a lower adapter coupled to a lower end of said housing and operable to engage said seal mandrel assembly;   a mandrel positioned inside said interior space of said housing and inwardly displaced from said inner wall of said housing, said mandrel having a tubular configuration defining a central bore for receiving a flow of fluid;   wherein said mandrel includes a mandrel port operable for fluid communication between said central bore and said annular space;   a piston encircling said mandrel that is movable along an axis defined by said central bore when urged to move;   a spring having an upper end operably coupled to said upper adapter and a lower end operably coupled to said piston, said spring being situated between said inner wall of said housing and said mandrel and movable between an extended configuration urging said piston downwardly and a compressed configuration being urged upwardly by said piston.   
     
     
         16 . The unloader valve assembly as in  claim 15 , wherein a volume of said annular space is increased when said piston is urged upwardly in said annular space and said spring is moved toward said compressed configuration. 
     
     
         17 . The unloader valve assembly as in  claim 16 , wherein said annular space has a volume sufficient to contain an entire volume of fluid displaced by penetration of said seal mandrel assembly into an upper bore of said cement retainer assembly so as to displace fluid therefrom. 
     
     
         18 . The unloader valve assembly as in  claim 17 , wherein said fluid displacement causes a pressure increase in said central bore that is communicated through said mandrel port and bears against a bottom of said piston so as to urge said piston upwardly to compress said spring toward said compressed configuration. 
     
     
         19 . The unloader valve assembly as in  claim 18 , wherein said piston moves upwardly in unison with fluid being displaced by penetration of the seal mandrel assembly into the cement retainer assembly. 
     
     
         20 . The unloader valve assembly as in  claim 15 , wherein fluid in said central bore is allowed to flow from said central bore through said port in said inner wall of said housing to said location outside said housing as said piston is urged upwardly.