NORTH RANKIN 'A' GAS RECYCLING PROJECT — DESIGN, CONSTRUCTION AND COMMISSIONING

Abstract

Gas recycling, to increase early production and total recovery of hydrocarbon condensate, was implemented on the North Rankin 'A' platform to take advantage of excess production capacity prior to the commencement of the LNG export phase. By recycling excess 'dry' gas back into the reservoir, condensate production has been doubled, to around 3 000 kl per day (19 000 barrels) per day and ultimate recovery increased.

The additional facilities installed included five injection wells, an additional production well, and a 23 MW gas turbine driven gas recompression facility that was retrofitted within existing facilities on the platform. Designed in-house, the facility involved relocation of some operating plant and piecemeal installation of a new 400 tonne module containing a 23 MW aero-derivative gas turbine driven high pressure (30 MPa) centrifugal compressor and ancillary equipment. The compressor set was extensively tested under full load conditions at the manufacturer's works in France before delivery.

Offshore construction was complicated by the congested working area and the difficulties of working in and integrating with live production facilities but was completed without major incidents or causing undue interference to platform production. Commissioning proceeded quite smoothly. Full operation was achieved within ten days of initial start-up, and the facility has continued to yield impressive production results.