Hydrostatic pressure actuated stroke amplifier for downhole force generator

A setting assembly for applying force to a downhole tool positioned in a wellbore, the setting assembly comprising:

• a downhole force generator having a moveable shaft, a power supply for moving the shaft a shaft stroke length;
• a stroke amplifier assembly having a piston slidably retained in a housing, the piston responsive to hydrostatic pressure to move a piston stroke length, the piston releasably coupled to the moveable shaft to allow relative motion between the shaft and the piston in a first direction;
• and
• the piston operably engageable with the downhole tool such that movement of the piston in a first direction along the piston stroke length in response to hydrostatic pressure partially sets the downhole tool, and such that movement of the moveable shaft in the same direction along the shaft stroke length partially sets the downhole tool.

A method for transmitting force to and setting a downhole tool positioned in a wellbore, the method comprising the steps of:

• moving a piston a piston stroke length in response to hydrostatic pressure in the wellbore, thereby transmitting a first force to the downhole tool by movement of the piston;
• partially setting the downhole tool in response to the first force;
• moving a powered shaft a shaft stroke length using a downhole force generator including a power supply, thereby transmitting a second force to the downhole tool by movement of the shaft;
• moving the piston and moving the shaft in the same direction;
• moving the piston and shaft at different speeds;
• permitting relative movement between the shaft and piston in only a first direction;
• and
• partially setting the tool in response to the second force.