Patent ID: 7614454

Claim:
A method for repeatably providing large operating forces to actuate a remote device in a well, and said well comprising: well production means penetrating to some depth; surface means for restricting or closing-off flow of product from the well and changing well pressure in so doing during an operating sequence of the well; downhole pressure storage chambers comprising a low pressure storage chamber and a high pressure storage chamber; valve means for communicating between the pressure storage chambers and prevailing well pressure; a piston/cylinder device coupled with the remote device to actuate the latter; and isolation valve means for controlling the supply of pressure energy from the storage chambers to the piston/cylinder device; in which the method comprises the following steps: (a) replenishably storing pressure in the storage chambers which are at respectively low and high extremes of well pressure during the operating sequence, such stored pressures being derived from fluid flow permitted by said valve means; and (b) repeatably operating the isolation valve means when required in order to apply differential pressure to the piston/cylinder device to actuate the remote device.