中国南海某区块超深水含浅层气井表层钻井工艺

Surface drilling technology for ultra-deep water containing shallow gas wells in a certain block of the South China Sea

近年来,随着深海油气勘探开发的不断深入,超深水井、含浅层气井钻探日益频繁,由于超深水井浅层安全密度窗口窄,且海底高压、低温,易形成水合物,给表层钻井带来了很大的挑战。在南海某水深1760m的区块表层钻井时,为克服前述难题,采取开路钻进方式,解决了闭路钻进无密度窗口难题;采用防水合物的盐水聚合物体系,优选钻井液密度,优化钻井液性能,并配合工程措施,解决了防塌、防漏和防水合物形成的难题;采用动态压井设备混浆,并加强钻井液储备后勤保障,解决了开路钻进需要大量钻井液的难题,成功钻探了3口井表层钻井。

In recent years,with the continuous deepening of deep-sea oil and gas exploration and development,drilling of ultra-deep wells and shallow gas wells has become increasingly frequent.Due to the narrow safety density window of shallow formations in ultra-deep water wells and the high pressure and low temperature of the seabed,hydrates are easily formed,posing great challenges to surface drilling.In a block with a water depth of 1760m in the South China Sea,to overcome the aforementioned dificulties,an open-hole drilling method was adopted to solve the problem of no density window in closed-hole drilling.A saltwater polymer system was used to prevent hydrate formation,and the drilling fluid density was optimized,and engineering measures were taken to solve the problems of collapse,leakage,and hydrate formation.Dynamic kill drilling(DKD)was used for mixing and strengthening the drilling fluid reserve logistics to solve the problem of requiring a large amount of drilling fiuid for open-hole drilling.Three wells were successfully drilled with surface drilling.