用地震层速度预测井底下部地层声波时差

由于地震数据的分辨率一般较低,对于复杂地质条件下初探井仅靠钻前的地震预测结果,其精度不能满足钻井施工的需要.利用钻前的地震层速度资料,结合某井上部井段的测井资料提取地震特征参数进行特征压缩,建立起层速度与声波时差之间的关系模型,利用该模型来对钻头下部地层的声波时差进行预测,进一步提高钻头下部地层的地层孔隙压力预测精度.应用结果表明,该方法地层孔隙压力随钻预测的精度高,为高温高压地质条件下地层压力预测提供了一种有效的方法.

On Predicting SDT of Formation Bellow Borehole Bottom with Seismic Horizon Velocity

For premier exploration well under complex geologic conditions,because resolution of seismic data is lower,predicting accuracy can not meet construction requirement only using predrilling seismic data.According to the data of seismic horizon velocity of predrilling and log information of top hole,picked up are seismic characteristic parameters that are compressed,then established is the relation model between the horizon velocity and sonic differential time(SDT).We predict the SDT of stratum bellow the bit with the model,and further improve the prediction accuracy of formation porous pressure of the stratum.Practical result indicates that this method has high prediction accuracy while drilling for formation porosity pressure and provides an useful method for the formation pressure prediction under high temperature/high pressure geologic conditions.