超深随钻方位电磁波前视测井响应分析与正则化反演

Response Analysis and Regularization Inversion of Ultra-Deep Azimuthal Electromagnetic Logging While Drilling for Look-ahead

  • 摘要: 为解决超深随钻方位电磁波前视测井信号与地质参数间非线性强、反演难度大及相关算法不成熟的问题,提出了一种可快速提取地层电阻率与地层界面参数的正则化反演方法。首先,通过理论分析明确正则化因子对迭代过程的影响,设计了正则化因子选取算法,限制模型迭代量不超过预设上限,以提升算法的稳定性;然后,分析了初始模型对迭代的作用,构建了初始模型数据库,以实现初始模型的快速筛选;最后,基于双层和多层地层模型,实现了前视电阻率窗帘图的快速反演。结果表明,正则化反演算法能够准确、快速地反演出地层电阻率与边界信息,且具备良好的稳定性。研究结果为未来电磁波前视测井资料处理奠定了理论基础。

     

    Abstract: To address the problems of strong nonlinearity between ultra-deep azimuthal electromagnetic look-ahead logging signals and geological parameters, high inversion difficulty, and immature related algorithms, a regularization inversion method is proposed for rapidly extracting formation resistivity and interface parameters. First, through theoretical analysis, the influence of the regularization factor on the iterative process is clarified, and a regularization factor selection algorithm is designed to restrict the model iteration amount within a preset upper limit, thereby enhancing algorithm stability. Then, the effect of the initial model on the iteration is analyzed, and an initial model database is constructed to achieve rapid selection of initial models. Finally, based on two-layer and multi-layer models, rapid inversion of look-ahead resistivity curtain graphs is generated. The results demonstrate that the regularization inversion algorithm can accurately and rapidly invert formation resistivity and boundary information, with good stability. The proposed inversion algorithm lays a theoretical foundation for the future processing of ultra-deep azimuthal electromagnetic measurements for look-ahead.

     

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