Hydraulic actuation of a downhole tool assembly

摘要

A downhole tool assembly is configured for repeated and selective hydraulic actuation and deactuation. A piston assembly is configured to reciprocate axially in a downhole tool body. The piston assembly reciprocates between a first axial position and second and third axial positions that axially oppose the first position. The downhole tool is actuated when the piston assembly is in the third axial position and deactuated when the piston assembly is in either of the first or second axial positions. A spring member biases the piston assembly towards the first axial position while drilling fluid pressure in the tool body urges the piston assembly towards the second and third axial positions. Downhole tool actuation and deactuation may be controlled from the surface, for example, via cycling the drilling fluid flow rate.

主权项

1. A downhole tool assembly comprising:
a downhole tool body having a through bore and configured for connecting with a drill string; a mandrel deployed in the tool body, the mandrel including at least one port; a piston assembly deployed in the mandrel, the piston assembly having the through bore extending therethrough, and the piston assembly including at least a valve piston and a cam piston configured to reciprocate axially in the mandrel between a first axial position and second and third axial positions opposing the first axial position, wherein the piston assembly is configured to actuate between the first and second axial positions when a guide pin coupled to the tool body is disposed within a first grooved track in the cam piston and when first and second flow rates are introduced to the through bore, respectively, wherein the piston assembly is configured to actuate between the first and third axial positions when the guide pin is disposed within a second grooved track in the cam piston, and wherein the guide pin transitions from the first grooved track to the second grooved track when a third flow rate is introduced to the through bore that is between the first flow rate and the second flow rate; and a spring member deployed in the tool body and disposed to bias the piston assembly towards the first axial position, wherein said mandrel port is in fluid communication with the through bore when the piston assembly is in the third axial position, the mandrel port being sealingly engaged with an outer surface of the piston assembly when the piston assembly is in either the first axial position or the second axial position, and fluid flow being permitted through the through bore when the piston assembly is in the first axial position, the second axial position, and the third axial position.