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本文研究了一种实用的井间电磁数据的反演方法,用以将井间电磁数据转换成地下地层的井间电阻率分布。该方法采用先验信息约束的正则化最小二乘迭代算法,对反演参数施加了可变的平滑约束。用有限元法(FEM)实现2.5维正演模型的电磁响应计算和反演过程中灵敏度矩阵计算时伪正演问题的计算。正则化最小二乘反演方法中用测井数据作为先验信息进行约束,利用该反演方法,对两个模型计算的合成井间电磁数据和中国东部孤岛油田的实测野外数据进行了反演,重建了井间电阻率剖面,获得了良好效果。野外实测数据的井间距为172m。灵敏度矩阵中的偏导数用基于互易原理的调和方程得到。合成数据和野外实际数据的反演结果显示,文中的反演方法对有随机噪音的井间电磁数据也具有良好的适应性和稳定性,可用于野外实测数据的处理解释。
In this paper, a practical inversion method of crosswell electromagnetic data is studied to convert crosswell electromagnetic data into crosswell resistivity distribution of underground formations. This method uses a regularized least-squares iterative algorithm with prior information constraints and imposes a variable smoothing constraint on the inversion parameters. Finite Element Method (FEM) for Calculating the Electromagnetic Response of a 2.5D Forward Model and Calculating the Pseudo - forging Problem in the Calculation of Sensitivity Matrix in the Inversion Process. In the regularized least-squares inversion method, log data are used as prior information to constrain the inversion data. The inversion method is used to invert the synthetic cross-well electromagnetic data calculated by the two models and the field data measured in the Gudong oil field in eastern China , Reconstructed crosswell resistivity profile, and achieved good results. Field measurements of well spacing of 172m. The partial derivatives in the sensitivity matrix are obtained using the harmonic equation based on the reciprocity principle. The inversion results of synthetic data and actual field data show that the inversion method in this paper also has good adaptability and stability to crosswell electromagnetic data with random noise and can be used to explain the field measured data.