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

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.