南海西部高温高压小井眼钻井技术

Drilling technology for HTHP slim hole in western South China Sea

莺歌海中深层地层地质情况复杂,地层压力高,温度梯度大,纵向上存在多套产层并且具有涌漏同层的特点,在保障现场作业安全的前提下,为防止出现复杂情况而无法到达勘探开发目的层,在设计时预留一层套管以应对复杂情况。DF13-1-A井因地层复杂,出现涌漏同存的复杂情况,被迫提前下入?177.8 mm套管封隔上部复杂井段,下部采用?149.225 mm井眼,面对小井眼钻具组合限制、井控压力大、储层保护压力大等技术难点,通过优化钻具组合、钻井液,采用压力实时监测等多项措施高质量地完成了该井的小井眼作业,为今后南海西部海域高温高压井小井眼作业提供了技术借鉴。

In the Yingge Sea, the middle and deep strata are characterized by complex geology, high reservoir pressure and high temperature gradient. And there are vertically multiple pay zones, and well kick and circulation loss occur in the same strata. While the safety of field operation is guaranteed, a section of casing is reserved according to the design to avoid the complex situations which hinder the exploration and development of target layers. Well DF13-1-A is located in the complex strata where well kick and circulation losscoexist, so ?177.8 mm casing has to be run in the hole in advance to isolate the upper complex hole section and ?149.225 mm hole isused in the lower section. Faced with the technical difficulties, e.g. restricted slim hole BHA (bottom hole assembly) and high difficultyof well control & reservoir protection, a series of measures are taken, such as BHA optimization, drilling fluid optimization and realtime pressure monitoring. And as a result, the slim hole operation is completed successfully. It provides some technical reference for the HTHP slim hole operation in western South China Sea in the future.