Trip sub assembly with check valve

Abstract

A trip sub device has a sliding piston which in a running position aligns a lateral port with a primary flowpath port to allow fluid flow through the device, and in an activated position closes the lateral port to allow pressure to build uphole from the device. The trip sub defines a bypass flowpath which includes at least one check valve to prevent upward flow of fluid in the bypass flowpath, while permitting downward flow.

1 . A trip sub device comprising:
 (a) a top sub and a bottom housing together defining an internal bore;   (b) a piston housing positioned within and sealed to the bottom housing, defining an internal passage and defining a primary flowpath port and a bypass flowpath, both flowpaths permitting fluid communication from the internal bore through the piston housing;   (c) a piston slidingly disposed and sealed within the piston housing, the piston defining a flowpath through the piston and at least one lateral port, wherein in a running position the lateral port is aligned with the primary flowpath port, and in an activated position the lateral port is closed by an internal surface of the piston housing, wherein the piston is moveable in response to pressure within the piston housing to slide downwards within the piston housing; and   (d) at least one check valve within the bypass flowpath, to prevent upward flow of fluid in the bypass flowpath, while permitting downward flow.   
     
     
         2 . The device of  claim 1 , further comprising a burst disc sealing an entrance to the bypass flowpath. 
     
     
         3 . The device of  claim 1 , wherein the top sub defines an equalization port, and the device further comprises an equalization sleeve slidingly disposed within and sealed to the top sub, wherein the equalization sleeve is moveable between a closed position which closes the equalization port and a retrieval positon which opens the equalization port. 
     
     
         4 . The device of  claim 1  wherein the piston comprises a ball seat for receiving a ball which closes the piston flowpath. 
     
     
         5 . The device of  claim 4  further comprising a resilient ball retaining ring having an inside diameter smaller than the ball diameter, permitting the ball to pass through pressure. 
     
     
         6 . The device of  claim 4  wherein the piston is retained in the running in position by at least one shear screw. 
     
     
         7 . The device of  claim 1 , further comprising a ratchet mechanism between the piston housing and the piston, which permits movement in an activation direction which closes the lateral port but restrains opposite movement. 
     
     
         8 . The device of  claim 1 , wherein the device comprises two check valves, configured in series.