FROM CONVENTIONAL WELLS TO MONOBORES GAS WELL CORROSION CASE HISTORIES IN THE SOUTH AUSTRALIAN SECTOR OF THE COOPER BASIN

摘要

The Cooper Basin is a mature hydrocarbon producing province facing increased competition from other natural gas resources in Australia. Operating and development costs must be competitive but at the same time equipment integrity must be monitored and maintained. This is in an environment subject to periodic floods where production equipment is exposed to reservoir fluids containing up to 45 % CO2, bottom hole temperatures of 180℃, wellhead temperatures up to 100℃, saline ground water and low resistivity clay soils. Corrosion control is a significant cost burden on the Cooper Basin Operation. Plant, pipeline and well corrosion prevention programmes in total cost the South Australian sector about $10 million per annum. Well repairs alone have cost about $40 million in direct costs since 1990. This paper briefly reviews the recent history of downhole and wellhead piping corrosion failures, the initiatives taken to reduce these failures and improve the cost base of the Moomba Operation. The introduction of two string Monobore wells compared to more conventional three string wells is also discussed.