利用地震反演技术钻前预测井壁稳定性

为有效克服钻井过程中出现的井壁失稳问题,基于褶积模型的测井约束反演方法,提出了利用地震层速度反演技术在钻前预测安全钻井液密度范围的模型。该预测模型充分利用探区内的地震记录资料,以测井信息和地质资料为约束条件,通过制作合成地震记录进行层位标定,建立初始波阻抗模型,运用宽带约束反演技术获得具有较高分辨率的波阻抗模型并最终得到速度资料。利用反演结果结合统计模型、趋势面模型、神经网络模型及岩石力学模型等常用预测模型可以实现钻前井壁稳定性预测。通过该方法反演出塔里木油田一口探井的层速度曲线,并在钻前预测出该井的安全钻井液密度范围,与实钻数据进行对比分析的结果表明,该预测方法具有良好的预测效果,可满足钻井工程的需要。

Predicting borehole stability before drilling by seismic inversion

The new model of predicting borehole stability before drilling was presented using seismic interval velocity inversion to control borehole instability effectively.The prediction model was based on logging constrained inversion method using convolution model.Based on the seismic information and constrained logging and geological data in prospecting area,horizon calibration by compiling synthetic seismic record and construction of initial wave impedance model were important factors in this technique.An ultimate wave impedance model and velocity data with high resolution could be obtained using broadband constrained inversion.The borehole stability prediction before drilling could be achieved based on inversion result and prediction models such as statistics model,trend surface model,neural network model and rock mechanics model.The interval velocity curve and safe drilling fluid density range of a exploration well in Tarim Oilfield have been predicted using the new method.Comparison of prediction result and field data indicate that the proposed method has the high accuracy and can meet the engineering requirement.