Wireline pump

Abstract

The present invention relates to a wireline pumping assembly ( 1 ) for being introduced in a wellbore ( 60 ) or a casing ( 61 ) and submerged in well fluid. The wireline pumping assembly extends in a longitudinal direction ( 50 ) and is adapted for connection with a wireline. Furthermore, the wireline pumping assembly comprises a pump section ( 2 ) comprising a tubular pump housing ( 20 ) providing a pump chamber ( 210 ); one or more inlets ( 21 ) provided in a lower part of the tubular pump housing; a first valve ( 22 ) for opening and closing the inlet; a plunger ( 23 ) being slidingly disposed in the pump chamber, the plunger comprising a second valven ( 242 ) controlling a flow of fluid from a first compartment ( 202 ) of the pump chamber below the plunger to an second compartment ( 203 ) of the pump chamber above the plunger; a pump rod ( 26 ) operably connected to the plunger and extending from the plunger through the tubular pump housing; and one or more outlets ( 27 ) provided in an upper part of the tubular pump housing. The wireline pumping assembly further comprises a linear actuator ( 40 ) arranged in association with the tubular pump housing for driving the pump rod, whereby, when the wireline pumping assembly is at least partially submerged into the well fluid, well fluid is drawn into the tubular pump housing through the one or more inlets, forced through the second valve of the plunger, and expelled through the one or more outlets in the upper part of the tubular pump housing, wherein the linear actuator comprises a tubular stroker cylinder ( 4 ) comprising one or more piston housings ( 47 ), one or more piston elements ( 46 ) slidingly disposed in the piston housing to divide the piston housing into a first chamber ( 41 ) and a second chamber ( 42 ), a stroker shaft ( 45 ) operably connected to the piston element and for connection with the pump rod to provide reciprocation of the plunger, a pump ( 5 ) for alternately supplying hydraulic fluid under pressure to the first chamber and the second chamber of the tubular stroker cylinder to reciprocate the piston element in the tubular stroker cylinder, and an electrical motor ( 6 ) for driving the pump. Furthermore, the invention relates to a use of the wireline pumping assembly, a method of initiating a well using a wireline pumping assembly and a method of optimising an initiation operation.

1 . A wireline pumping assembly ( 1 ) for being introduced in a wellbore ( 60 ) or a casing ( 61 ) and submerged in well fluid, the wireline pumping assembly extending in a longitudinal direction ( 50 ) and being adapted for connection with a wireline ( 60 ), and the wireline pumping assembly comprising a pump section ( 2 ) comprising:
 a tubular pump housing ( 20 ) providing a pump chamber ( 210 ),   one or more inlets ( 21 ) provided in a lower part of the tubular pump housing,   a first valve ( 22 ) for opening and closing the inlet,   a plunger ( 23 ) being slidingly disposed in the pump chamber, the plunger comprising a second valve ( 242 ) controlling a flow of fluid from a first compartment ( 202 ) of the pump chamber on one side of the plunger to a second compartment ( 203 ) of the pump chamber on the other side of the plunger,   a pump rod ( 26 ) operably connected to the plunger and extending from the plunger through the tubular pump housing, and   one or more outlets ( 27 ) provided in an upper part of the tubular pump housing,   wherein the wireline pumping assembly further comprises:   a linear actuator ( 40 ) arranged in association with the tubular pump housing for driving the pump rod, whereby, when the wireline pumping assembly is at least partially submerged into the well fluid, well fluid is drawn into the tubular pump housing through the one or more inlets, forced through the second valve of the plunger, and expelled through the one or more outlets in the upper part of the tubular pump housing, wherein the linear actuator comprises:   a tubular stroker cylinder ( 4 ) comprising one or more piston housings ( 47 ),   one or more piston elements ( 46 ) slidingly disposed in the piston housing to divide the piston housing into a first chamber ( 41 ) and a second chamber ( 42 ),   a stroker shaft ( 45 ) operably connected to the piston element and for connection with the pump rod to provide reciprocation of the plunger,   a pump ( 5 ) for alternately supplying hydraulic fluid under pressure to the first chamber and the second chamber of the tubular stroker cylinder to reciprocate the piston element in the tubular stroker cylinder, and   an electrical motor ( 6 ) for driving the pump.   
     
     
         2 . A wireline pumping assembly ( 1 ) according to  claim 1 , wherein the linear actuator comprises a plurality of piston elements ( 46 ) slidingly disposed in a plurality of piston housings  47  and operably connected to the stroker shaft. 
     
     
         3 . A wireline pumping assembly ( 1 ) according to  claim 1  or  2 , further comprising a plug device ( 3 ) for providing a seal in an annulus ( 62 ) between the wireline pumping assembly and the casing, the plug device comprising:
 a base part ( 31 ) connected with the tubular pump housing and having a through-going bore ( 32 ), and 
 one or more sealing elements ( 34 ) disposed around the base part, extendable from the base part for sealing off the annulus. 
 
     
     
         4 . A wireline pumping assembly ( 1 ) according to  claim 3 , wherein the base part is the tubular pump housing. 
     
     
         5 . A wireline pumping assembly ( 1 ) according to  claim 3 , wherein the base part is part of the tubular stroker cylinder and the outlet(s) ( 27 ) of the pump section are arranged in the linear actuator. 
     
     
         6 . A wireline pumping assembly ( 1 ) according to  claims 3 - 5 , wherein the plug device further comprises an anchor mechanism ( 33 ) for fixating the wireline pumping assembly in the well, the anchor mechanism being slidingly disposed around the base part and comprising a plurality of setting slips ( 331 ) extendable from the base part in a substantially radial direction for engagement with the casing. 
     
     
         7 . A wireline pumping assembly ( 1 ) according to  claims 3 - 6 , wherein the plug device further comprises a compression sleeve ( 38 ) slidingly disposed around the base part for compressing the one or more sealing elements, and wherein the sealing elements are adapted to extend from the base part to seal off the annulus when the compression sleeve is displaced in the longitudinal direction towards the one or more sealing elements, thereby applying a compression force to the one or more sealing elements. 
     
     
         8 . A wireline pumping assembly ( 1 ) according to  claim 7 , wherein the compression sleeve comprises a cone-shaped section ( 381 ) facing towards the anchor mechanism, the cone-shaped section being adapted to force the setting slips in a radial direction, at least upon activation of the anchor mechanism, when the plurality of setting slips are displaced towards the compression sleeve, thereby engaging the cone-shaped section. 
     
     
         9 . A wireline pumping assembly ( 1 ) according to any of the  claims 3 - 8 , further comprising an equalisation valve ( 37 ) for equalising a differential pressure across the plug, at least prior to disengaging of the plug, when the plug device is set in a well. 
     
     
         10 . A wireline pumping assembly ( 1 ) according to any of the  claims 3 - 9 , further comprising one or more sensors ( 39 ) for measuring a differential pressure across the plug device when the plug device is set in a well. 
     
     
         11 . A wireline pumping assembly ( 1 ) according to any of the preceding claims, further comprising an anchor section ( 8 ) for anchoring the wireline pumping assembly in the well, the anchor section comprising a plurality of hydraulically activatable anchoring elements ( 81 ) extendable from the tool body, for engagement with the casing. 
     
     
         12 . A wireline pumping assembly ( 1 ) according to any of  claims 1 - 11 , wherein the linear actuator comprises:
 an electric linear motor ( 51 ), and   the stroker shaft ( 45 ) driven by the electric linear motor for connection with the pump rod to provide reciprocation of the plunger.   
     
     
         13 . A wireline pumping assembly ( 1 ) according to any of the preceding claims, wherein the first valve is a standing valve fixed in relation to the tubular pump housing, and the second valve is a travelling valve movable with the plunger in relation to the tubular pump housing. 
     
     
         14 . A wireline pumping assembly ( 1 ) according to any of the preceding claims, wherein the wireline pumping assembly is adapted to pump at a flow rate of approximately 5-15 litres per minute. 
     
     
         15 . A wireline pumping system ( 10 ) comprising a wireline pumping assembly ( 1 ) according to any of the  claims 1 - 14 , and a plug device ( 3 ) for providing a seal in an annulus ( 62 ) between the plug device and the casing, the plug device comprising:
 a base part ( 31 ) having a through-going bore ( 32 ) adapted to be connected with the tubular pump housing of the pump section, and   one or more sealing elements ( 34 ) disposed around the base part, extendable from the base part for sealing off the annulus, wherein the wireline pumping assembly is adapted for connection with the plug device downhole following setting of the plug device in the well.   
     
     
         16 . Use of the wireline pumping assembly according to any of the  claims 1 - 14  or a wireline pumping system according to  claim 15  for initiation of a killed well by removing water present in the well using the pumping action provided by the pumping assembly. 
     
     
         17 . A method of initiating a well using a wireline pumping assembly according to any of the  claims 1 - 14 , comprising the step of:
 inserting the wireline pumping assembly into the wellbore,   setting a plug device for providing a seal in an annulus ( 62 ) between the plug device and the casing, the plug device comprising:
 a base part ( 31 ) having a through-going bore ( 32 ) adapted to be connected with the tubular pump housing of the pump section, and 
 one or more sealing elements ( 34 ) disposed around the base part, extendable from the base part for sealing off the annulus, 
   operating the pump section of the wireline pumping assembly to pump fluid past the plug device until a pressure below the plug device is sufficient to make the well run by itself,   equalising the pressure over the plug by operating the equalisation valve, and   removing the wireline pumping assembly from the well.   
     
     
         18 . A method of optimising an initiation operation, comprising the steps of:
 determining a pressure level in the well below the plug device, sufficient to make the well run by itself,   continuously monitoring the pressure in the well below the plug device while the pump section is operated to pump fluid from below the plug device to above the plug device, and   determining when the predetermined pressure level is reached, following which the operation of the pump section may be stopped.