Abstract: An undersea integrated repressurization system includes a first undersea separator (1) on the sea bottom (2) at which output from one or more wells (A, B, C and D) is collected with gas flowing through a low pressure gas line (3) to production platform (4) and oil flowing to a repressurization well (5). A power gas line (6) extends from compressor (7) on production platform (4) for injection of gas into the lower end of a pipe adjacent the bottom of the repressurization well (5), through an opening (8) whereby the oil and gas rise through the pipe to a second undersea separator (9) on the sea bottom (2). The separated oil then enters oil pipeline (10) along which the oil flows and the separated gas enters a high pressure gas pipeline (11) which carries the gas, both leading to a production platform (4).