储层深度预测误差分析及规避方法

Error in Reservoir Depth Prediction and Avoidance Methods

随着油气田开发进入中后期,为解决常规定向井多层合采导致的层间矛盾、含水率差异等问题,水平井分层系开采已受到广泛关注。受水平井钻井工程技术难度大、开发成本高等制约,开发过程中对水平井目的层顶面深度预测精度要求高,目前通常采用"实钻井资料为主、井间地震约束为辅"的方法预测,然而地质、地球物理、工程等方面均能对储层深度预测产生影响。主要从这3方面分析深度误差产生原因:地质上储层变化、地层倾角与钻井方向关系;地球物理平面速度变化、地震资料分辨率对储层厚度刻画精度以及浅层气影响;工程上钻具拉伸、扶正器位置以及测试仪器本身误差等方面导致的储层深度误差,针对这些深度误差产生原因,分别提出相应规避方法。利用以上研究成果指导水平井随钻实时调整,实现了渤海湾QH油田储层深度预测误差控制在1.5 m以内,达到质量效益双丰收。

With the oil and gas fields entered the middle-late stage of development,separate layer development in horizontal wells has attracted widespread attention in order to solve interlaminar contradiction,water content and other issues caused by multi-layered commingled production in conventional directional well. Due to great engineering and technical difficulty,high development costs and other constraints in horizontal well drilling,horizontal wells' depth prediction requires high precision and the method "based on drilling data,constrained by cross well seismic"is generally used to predict the depth. However,the prediction of reservoir depth is effected by geology,geophysics,drilling and well completion. The errors from the above three aspects were analyzed and corresponding method was put forward to avoid the them,including reservoir changes,the relationship between formation dip and direction of drilling in geology; the plane speed changes,precision of reservoir thickness and shallow gas in geophysics; drilling tool stretch,centralizer's location and the instrument itself error,etc. in the drilling and well completion process. Through above study to guide real-time adjustment while drilling horizontal wells. The error in reservoir depth prediction controled in less than 1. 5 m in QH Oilfield,Bohai Bay Basin was realized,successfully guided the landing of horizontal wells and has made great harvest in quality and efficiency.