Pumpdown assist tool for wireline operations

Abstract

A pumpdown assist device has an outer housing comprising a top connection, a spring housing, a piston housing and a bottom connection, all defining a central bore; a mandrel disposed and slidably moveable within the central bore between a run-in-hole (RIH) position and a pull-out-of-hole (POOH) position, the mandrel comprising a head portion, a central portion and a bottom stem, all defining a central passage, wherein the head portion comprises a flow restriction from the top connection central bore; a piston connected to the mandrel and having a sloped ramp surface; a plurality of pads slidably disposed on the piston ramp surface and which are transversely moveable through pad cutouts defined by the piston housing; and biasing means disposed within the spring housing, for urging the mandrel in its POOH position. The device is installed into a bottom hole assembly (BHA) and is urged into a wellbore by pumping down fluid. When fluid pressure within the device top connection exceeds the biasing means force, the mandrel is shifted to the RIH position and the pads are deployed outwards. Sufficient flow rate is then maintained to maintain deployment pressure in the device top connection until the BHA reaches a desired depth. The pads may then be retracted into a POOH position by reducing pumpdown flow rate.

1 . A pumpdown assist device comprising:
 (a) an outer housing comprising a top connection, a spring housing, a piston housing and a bottom connection, all defining a central bore;   (b) a mandrel disposed and slidably moveable within the central bore between a run-in-hole (RIH) position and a pull-out-of-hole (POOH) position, the mandrel comprising a head portion, a central portion and a bottom stem, all defining a central passage, wherein the head portion comprises a flow restriction from the top connection central bore;   (c) a piston connected to the mandrel and having a sloped ramp surface;   (d) a plurality of pads slidably disposed on the piston ramp surface and which are transversely moveable through the piston housing;   (e) biasing means disposed within the spring housing, for urging the mandrel in its POOH position.   
     
     
         2 . The device of  claim 1 , wherein the pads comprise a rail which mates with a channel formed on the piston, to guide the pads as they slide along the piston ramp surface. 
     
     
         3 . The device of  claim 1  wherein the pads comprise a shape which matches a cutout shape through the piston housing, which limits non-transverse movement of the pads. 
     
     
         4 . The device of  claim 1 , wherein the biasing means comprises a coil spring. 
     
     
         5 . The device of  claim 1 , wherein the spring housing and/or piston housing defines a plurality of openings for fluid circulation. 
     
     
         6 . The device of  claim 1 , wherein the piston has a quadrilateral cross-sectional shape, with four sloped ramp surfaces. 
     
     
         7 . A method of pumping down a wireline bottom hole assembly (BHA), comprising the steps of:
 (a) assembling a BHA with a device, wherein the device is responsive to fluid pressure to outwardly deploy one or more pads to reduce flow area around the BHA;   (b) pumping down fluid to urge the BHA into the wellbore and deploy the pads outwards;   (c) maintaining sufficient flow rate to maintain deployment pressure until the BHA reaches a desired depth; and   (d) retracting the pads inwardly by reducing pumpdown flow rate.   
     
     
         8 . The method of  claim 7 , wherein the device comprises a device of  claim 1 . 
     
     
         9 . A bottom hole assembly for wireline plug and perf, comprising a device which is responsive to fluid pressure to outwardly deploy one or more pads to reduce flow area around the BHA. 
     
     
         10 . The bottom hole assembly of  claim 9  wherein the device comprises a device of  claim 1 .