泥页岩地层孔隙压力预测新方法

A new method for prediction of pore pressure in shale formation

Eaton公式和Yan公式都是比较常用的孔隙压力预测方法,但它们在计算过程中都需要求取正常压实速度,而正常压实速度一般是由浅层正常压实地层的纵波速度拟合得来,在浅层纵波时差曲线缺失或质量较差的情况下往往难以准确求取。基于此,提出了一种新的方法来预测孔隙压力,结合Eaton公式和Yan公式,在不求取正常压实速度的情况下预测孔隙压力,避免了上述问题。通过实际测井数据的标定,发现新方法预测的结果比用Eaton公式和Yan公式的预测效果好,并利用新方法研究了密度和纵波速度对孔隙压力的影响。此外,新方法还被成功地应用到利用地震资料预测孔隙压力剖面,且通过井资料的标定发现预测结果可信度较高。

Eaton’s equation and Yan’s equation are both commonly used in pore pressure prediction,but they both require normal compaction velocity in the calculation process.The normal compaction velocity is generally fitted by the longitudinal wave velocity of shallow normal compaction formations,and it is often difficult to obtain accurately when the shallow longitudinal wave time difference curve is missing or the quality is poor.To solve the problem,a new method for pore pressure prediction has been proposed.This method combines Eaton’s equation and Yan’s equation to predict the pore pressure without calculating the normal compaction velocity,avoiding the above-mentioned problems.Through the calibration of actual logging data,it is found that the prediction results of the new method are better than those of Eaton formula and Yan formula,and the new method is used to study how the density and longitudinal wave velocity affect the pore pressure.In addition,the new method has been successfully applied to predict the pore pressure profiles using seismic data,and the calibration of well data has found that the prediction results are highly reliable.