区域油田地应力及井壁稳定性综合预测方法

Predicting method of regional in-situ stress of oilfield and borehole stability

基于地质统计原理,提出一种综合利用地震和测井资料预测区域油田地应力和待钻井井壁稳定性的方法:首先利用测井和测试资料,精确计算已钻井处的地应力;同时,从三维地震记录中提取并优化地震属性,将油田地应力作为区域化变量,根据地震和测井信息之间良好的空间相关性,通过贝叶斯克里金方法,计算所研究区块的三维地应力数据体。在此基础上,利用井壁稳定力学模型,预测区块内待钻井的安全钻井液密度窗口,以有效控制钻井中的井壁失稳问题。油田实际应用表明,基于地质统计方法进行的区域油田地应力预测精确度较高,为进一步预测井壁稳定性提供了可靠依据。

This paper proposes a method, which can comprehensively predicts the regional in-situ stress of oilfield and borehole stability of undrilled well through the use of seismic data and logging data based on geostatistics theory. The in-situ stress of drilled well can be calculated precisely by using logging data and testing data. Meanwhile, the optimized seismic attributes can be extracted from 3D seismic records. With the in-situ stress of oilfield given as regionalized variables, the 3D in-situ stress data volume of the study area can be calculated according to the good spatial correlations between logging data and seismic data and by using Bayesian Kriging method. Safe drilling fluid density window of undrilled wells in the given area can be predicted through the use of the mechanical model of borehole stability so as to control the borehole instability during drilling. The prediction precision of regional in-situ stress of oilfield is satisfactory based on geostatisties, which can provide the reliable basis in future borehole stability prediction.