定向井随钻井壁稳定预测方法及其应用

A method of borehole stability prediction while drilling directional wells and its application

常规井壁稳定预测方法不适用于定向井。根据岩石力学和地震反演原理提出随钻预测定向井稳定性的新方法,包括钻前预测与随钻修正2个操作步骤。通过分析地震数据与岩石力学参数之间的定量关系,建立了包含孔隙压力、地应力、岩石强度等井壁稳定参数和地震记录的非线性模型,基于其利用地震资料直接反演井壁稳定参数,实现钻前预测井壁稳定性,为钻井设计提供依据。实钻中结合定向井的实际施工情况,通过实时反演对钻前预测的井壁稳定数据模型进行随钻修正更新,及时优化调整钻井方案以避免工程复杂故障。该方法在涪陵页岩气田进行了应用,结合"井工厂"钻井作业模式,形成了井壁稳定预测现场操作方案。现场应用情况表明该方法预测精度较高,具有良好的实时操作性能,有利于定向井的安全快速钻井。

The conventional prediction methods of borehole stability are not suitable for directional wells.Based on the rock mechanics and seismic inversion principles,a new prediction method of directional well stability while drilling is presented in two operation steps,i.e.,pre-drilling prediction and while-drilling correction.According to the quantitative relationship between seismic data and rock mechanic parameters,a nonlinear model was created with seismic records and borehole stability parameters including pore pressure,geo-stress,rock strength and etc.On this basis,borehole stability parameters are directly inversed using seismic data,so as to further predict borehole stability before drilling and provide a foundation for drilling design.According to the construction situation of directional wells,real time inversion is applied in actual drilling for while-drilling correction and upgrade of pre-drilling borehole stability data model,so as to timely optimize and adjust drilling schemes with the purpose of avoiding complex engineering fault.This method has been applied in Fuling shale gas field,and constitutes the field operation scheme of borehole stability prediction together with the drilling process of'well factory'.The field application shows that this method has high prediction accuracy and good performance of real time operation,advantageous to safe and fast drilling of directional wells.