欠平衡钻井技术在超高压地层中的研究与应用

Research and Application of Unbalanced Drilling in Abnormal High Pressure Formation

川东地区高陡背斜构造地质情况复杂，井下压力异常。川东某井在嘉二2钻遇异常高压气层，通过对钻井液密度与气测全烃值和钻井液静止时间相互关系的研究，利用密度、全烃值、钻井液静止时间的相互控制关系，进行欠平衡钻井和起下钻作业，保证了井下安全，取得了显著效果。

The complex geologic characters and abnormal high pressure are existed in high dipped and anticlinal structure in the east of Sichuan. A gas reservoir withabnormal high pressure was encountered in the second section in Jiaer Formation in the region.Having been studied the inter-relationships of drillingfluid density, total hydrocarbon values of gas logging and the rest time of the drilling fluid, they are used in unbalanced drilling and making a trip, the downhole safety are ensured and ed effect are gained.