南海高温高压钻完井关键技术及工程实践

Key technology and practice of HTHP well drilling and completion in South China Sea

南海是全球三大海上高温高压区域之一,地质构造复杂,已钻井井底温度249℃、压力梯度2.4 MPa/100 m、CO_2含量50%,该区域油气资源勘探开发长期受异常压力预测误差大、井筒泄漏及环空带压严重、测试安全风险高、成本巨高等钻完井技术瓶颈制约。全面总结了近20年南海高温高压钻完井在异常压力精确预测及控制、多级屏障井筒完整性、多因素多节点测试、优质高效作业等4个方面研究形成的关键技术及工程实践,展望了南海高温高压钻完井技术未来发展方向。以期为进一步加快南海及其他地区类似高温高压区块油气资源高效可持续勘探开发提供指导。

South China Sea is one of the three high-temperature and high-pressure offshore oil and gas regions in the world.The geological structure is complicated,with the bottom hole temperature being up to249 ℃,the pressure gradient 2.4 MPa/100 m,and the CO_2 content 50%.The exploration for and development of oil and gas resources in this region have long been afflicted by difficulties in forecasting the abnormal pressure,lost circulation,serious pressure in the annulus,high risks involved in well testing,and finally the unreasonable high cost.This paper summarizes the four major technical achievements and engineering practices of high temperature and high pressure drilling in South China Sea in the last 20 years,i.e.,forecasting and control of abnormal pressure,multi-barrier wellbore integrity,multi-factor and multi-node testing,and high quality and efficiency operations.It also provides an outlook of the future development in drilling technology for South China Sea oilfields,with a view to provide guidance for further speeding up the efficient and sustainable exploitation of oil and gas resources in South China Sea and similar regions.