Downhole power generating apparatus

A downhole power generating system comprising:

• hydrocarbon reservoir tubing;
• a low pressure chamber having an inlet and an outlet for cycling tubing fluid;
• a floating piston separating the low pressure chamber into an upper section and a lower section, the floating piston cyclically responsive to a cycle of tubing fluid and a another cycle of tubing fluid;
• a high pressure chamber;
• a first flow through path fluidly for coupling a fluid from the lower section of the low pressure chamber to the high pressure chamber in response to a cyclical response of the floating piston;
• a second flow through path fluidly for coupling the fluid from the high pressure chamber to the lower section of the low pressure chamber in response to another cyclical response of the floating piston;
• and
• a turbine to generate power in response to at least one selected from a group comprising the fluid coupled from the lower section of the low pressure chamber to the high pressure chamber and the fluid coupled from the high pressure chamber into the lower section of the low pressure chamber, wherein the turbine is disposed in the first flow through path or the second flow through path.

A method for generating power downhole, the method comprising:

• coupling a high pressure chamber and a low pressure chamber to hydrocarbon reservoir tubing;
• placing the hydrocarbon reservoir tubing downhole;
• pumping tubing fluid into an inlet of the low pressure chamber;
• using a floating piston to pump fluid from a lower section of the low pressure chamber through a flow through path and into the high pressure chamber;
• releasing the tubing fluid from an outlet of the low pressure chamber;
• pumping the fluid from the high pressure chamber into the lower section of the low pressure chamber using another flow through path;
• and
• generating power using a turbine that is disposed in the flow through path or the other flow through path in response to pumping fluid from at least one selected from a group comprising the lower section of the low pressure chamber into the high pressure chamber and the high pressure chamber into the lower section of the low pressure chamber.