Patent ID: 9708873
Date: 2017-07-18
CPC Classifications: E21B

Claim:
1. A downhole tool, comprising: a hydraulic assembly, an arm assembly, the arm assembly comprising a wheel, the arm assembly being movable between a retracted position and a projecting position in relation to a tool housing; a hydraulic motor configured to rotate the wheel, rotation of the wheel being adapted to drive the downhole tool within a wellbore downhole; a hydraulic pump unit configured to generate a first pressurized fluid stream at a first pressure and a second pressurized fluid stream at a second pressure, the first pressure being variable compared to the second pressure; an arm activation assembly configured to move the arm assembly between the retracted position and the projecting position, the hydraulic motor being configured to rotate the wheel to drive the downhole tool when the arm assembly is in the projecting position, the arm activation assembly being in fluid connection with the first pressurized fluid stream and the hydraulic motor being in fluid connection with the second pressurized fluid stream; a hydraulic control block adapted to control the pressure of the first pressure and the second pressure; and, the hydraulic control block comprising a sequential valve configured to control a sequence of retraction of the arm assembly, a projection of the arm assembly and a rotation of the wheel; wherein the sequential valve is fluidly connected with one of the fluid streams and changes between an open and a closed position based upon the variable pressure of the other fluid stream.