济阳拗陷地层压力预测方法

依据沉积物压实过程所建立的力学关系表明，孔隙流体压力Pp与上覆岩层压力Ph及有效应力Pe有关。其中Ph可由地层的密度求取，Pe可由叠加速度获得。通过对济阳拗陷山东探区地层压力预测精度敏感性的分析，认为地震速度变化及上覆岩层压力梯度对反映地层压力最敏感，于是统计了济阳拗陷100口井声波时差和实测压力资料，同时解释了该区约1000个点的地震速度谱资料，基本查清了造成该区地震速度谱资料异常的因素，建立了该区地震速度谱资料异常干扰校正模型；分别用测井密度、平均密度方法完成了三个凹陷区的正常地层压力模型计算；形成一套技术先进、易于操作、实用性强的地层压力预测方法。应用这些新方法对15口预探井进行地层压力预测，结果与实钻数据的地层压力梯度绝对误差小于0．1g／cm^3，相对误差最大值小于10％，克服了过去地层压力预测存在的不稳定、起伏大的缺陷，满足了预探井地层压力预测的要求。

Predicting method of formation pressure in Jiyang Depression.

The mechanical relation built based on sedimentary compaction process showed that the pore-fluid pressure P e is related to overburden pressure P h and effective pressure P e,among which the P h can be gained by the density of formation,P e by stack velocity.It considered by the analysis of sensibility of predicted precision of formation pressure in Shandong area of Jiyang depression that the change of seismic velocity and overburden pressure gradient are sensitive to formation pressure,so that the data of interval transient time and real-measured pressure of 100 wells in Jiyang depression have been counted up and the data of seismic velocity spectrum of 1000 positions in that area have been interpreted,that basically clarified the factors caused anomaly of seismic velocity spectrum in the area and built the model of correcting the interference resulted from anomaly of seismic velocity spectrum data;the computations of models of normal formation pressure for three sags have been finished separately by logging density and average density,forming a set of predicting methods for formation pressure characterized by advanced technology,easy to operation and good practicality.Application of these methods to predict the formation pressure of 15 prospecting wells,the absolute errors between the predicted results and the formation pressure coefficient of real drilling data are less than 0.1g/cm 3 and the maximum relative errors are less than 10%,overcoming unstable and big skip's shortcomings the former prediction of formation pressure had,which met the demands of prospecting drilling for the prediction of formation pressure.