英科1井超高压地层压力预测技术研究

TECHNOLOGICAL RESEARCH ON THE PRESSURE PREDICTION OF OVERPRESSURED FORMATION IN WELL YINGKE-1

英科1井是1口井深6406m，含有多层高压盐水层，地层压力高达140～150MPa的超高压科学探索井。该井位于塔里木盆地西南部的英吉沙背斜构造上，地层条件相当复杂，属于山前构造带，也应力异常，用常规地层压力预测方法预测的精度低。本文就地应力异常对地层压力预测的影响进行了修正，运用修正的dc指数法提高了英科1井地层压力预测的精度。同时，通过对PDC钻头钻速模式的试验研究，证明PDC钻头的资料可以用来进行地层压力预测。根据预测结果，及时、合理地调整钻井液密度，比较顺利地钻过了近百层高压盐水层和膏泥岩地层，减少了井下复杂情况和事故的发生。在该构造上第一次成功地完成了1口超高压深井。

Well Yingke- 1 is an overpressured deep well with a depth of 6406m, which contains multilevel high pressure brine water layers. Its formation pressure is high as much as 140 ~ 150MPa. The well located at Yingjisha anticline structure, southwest of Talimu Basin, with quite cornplex formation, piedmont structure belt and abnormal ground stressThe conventional prediction method of formation pressure had a low accuracy for predicting the pressure of formations with abnormal ground stress on piedmont structure belt. This paper corrected the effect of ground stress anomaly on formation pressure prediction so its prediction accuracy was improved by corrected dc exponential method. Meantime, the drilling rate mode of PDC bit was studied in lab for proving that PDC bit data can be used to predict formation pressure- According to the prediction results, the density of drilling fluid was ad justed promptly and properly and almost 100 high pressure brine water layers and gyps shale layers were drilled through- This reduced the occurrence of underground complicated conditions and accidents. An overpressured deep well was first accomplished on the structure.