Patent ID: 7926501

Claim:
A method for recovering power fluid from a device under water and for pumping recovered power fluid to a surface of the water, the method comprising: flowing fluid from a subsurface apparatus to a subsurface recovery system, the fluid initially provided to the subsurface apparatus to power the subsurface apparatus; and the subsurface recovery system including pump apparatus for selectively pumping recovered fluid to a fluid container above a surface of the water, wherein the pump apparatus includes a two-chamber housing with a movable pumping piston therein, the two-chamber housing including a first chamber and a second chamber, the method further comprising: by moving the movable piston, pumping fluid in a line to the surface from the first chamber while the second chamber fills with fluid, and then pumping fluid to the surface from the second chamber while the first chamber wherein a first reserve capacity apparatus selectively provides fluid to the first chamber or to the second chamber; and a second reserve capacity apparatus selectively provides fluid to the second chamber or to the first chamber; the method further comprising selectively providing fluid to the first chamber or to the second chamber from the first reserve capacity apparatus; and selectively providing fluid to the second chamber or to the first chamber from the second reserve capacity apparatus.