基于Eaton法的孔隙压力预测需要高精度的深度域层速度模型作为保障,但常规层速度建模方法的精度很难满足孔隙压力预测精度的需求.针对泥岩欠压实异常高压地层低速的特点,创新提出炮域速度相干反演方法进行初始速度模型建立,基于ADCIGS (角度域共成像点道集)剩余曲率分析方法进行速度收敛,基于层位约束的网格层析成像方法进行局部修饰,利用上述的3种方法组合成一套具有针对性的异常高压地层层速度建模技术流程.利用新建立的层速度建模流程对渤海M工区进行具有针对性的深度域层速度场建模及孔隙压力预测工作.基于新流程得到的层速度模型与已钻井声波测井速度吻合度非常好,新流程得到的层速度模型计算的孔隙压力系数与已钻井古近系实测压力点完全吻合,其精度远远高于常规方法.由实际数据应用证明,基于高精度深度域层速度建模的孔隙压力预测方法是有效且可行的,该方法能够在保证计算效率的同时有效提高预测孔隙压力的精度,从而保证钻井施工的安全.%The prediction of pore pressure through Eaton method requires a highly precise depth domain interval velocity model to make correct predictions,but the velocity from conventional interval velocity modeling methods cannot reach such an accuracy.So,an innovative prediction method is proposed,which is specifically suitable for the poorly compac-ted mudstone formation,characterized by abnormal high pressure and low velocity.Shot domain velocity coherence in-version method is proposed to establish the initial velocity model.The residual curvature analysis of common imaging point gather in angle domain (ADCIGS) is used for velocity convergence.The grid tomography based on layer con-straints is used to make local modifications.These three methods are integrated as a new interval velocity prediction process,specific for abnormal high pressure zones.The new process is then applied to the modeling of depth domain in-terval velocity field and prediction of pore pressure in the working area M of Bohai Sea.As a result,the interval velocity model matches well with the acoustic logging velocity,and the pore pressure coefficient calculated by the new process is identical with the Palaeogene formation pressure measurements.Judging from these,we can see its accuracy is much higher than the conventional method.The realworld case study demonstrates that the depth domain interval velocity modeling can make highly accurate predictions on pore pressure,and thus are effective and feasible.These methods can improve the accuracy of pore pressure prediction while maintaining the efficiency of calculation,and thus can facilitate the safety of drilling engineering.
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