随钻地层孔隙压力预测技术初探

随钻地层孔隙压力预测技术,是在钻进过程中利用随钻地层孔隙压力监测结果,对钻前的地震预测模型和结果进行修正,并根据新修正的模型,对钻头下部未钻开地层的孔隙压力进行再预测,以此来提高地层孔隙压力的预测精度。在塔西南琼002井进行了现场试验。首先收集了该开区的地震层速度资料,并进行地层压力预测处理。施工过程中,利用dc指数法和岩石强度法进行地层压力随钻监测。钻至3500m时,根据监测结呆对地震预测模型进行反演修正,根据修正结果进行了再一次修正。经钻后证实,新预测的结果平均误差为12%,比原预测结果平均误差30%减少了18个百分点,致使琼002井钻井作业顺利,并提前完钻。

PRELIMINARY STUDY ON WHILE DRILLING PORE PRESSURE PREDICTION

While drilling pore pressure prediction is a technique to correct the model and its result of prior drilling seismic prediction using the results of while drilling pore pressure prediction, then to predict again the pore pressure of virgin formation before the bit based on the corrected newly model in order to improve the accuracy of pore pressure prediction. A field pilot of this technique was done in well Chong 002 in westsouth Tarim. The seismic lay-er velocity data of this well block was collected first and then processed for formation pres-sure predictlon. Durlng operation, dc exponent method and rock strength technique were uti-lized for while drilling pore pressure monitoring. At 3500m,an inversion correction was ap-plied to the seismic prediction model on the basis of monitor result and then, correction ap-plied once more based on the corrected result. Drilling practice proves that the average error of newly predicted result is 12%, 18% less than the average error of 30% in previous predic-tion, resulting in a smooth drilling and drilling completion ahead of schedule in well Chong 002.