井间电磁成像测井数值模式匹配算法

Numerical Model Matching Method for Cross-well Electromagnetic Imaging Logging

介绍井间电磁成像系统应用的关键技术,研究将数值模式匹配算法(NMM)引入该系统中进行正演计算的可行性。分析了NMM的基本原理,结合井间电磁成像系统的工作流程,简化了NMM法的计算步骤,采用并行计算,编写了相应的程序。在均匀地层与水平成层一维地层模型下,将该方法与解析解进行对比,验证了其正确性;在轴对称二维地层模型下,将该方法与积分方程法、有限元法进行对比,证明该方法在大井间距中正演计算的可行性,且显著提高了计算速度。该方法对基函数的节点选择要求很高。证明了将NMM应用于井间电磁成像进行快速正演计算有很大的发展潜力与应用前景。

The key technique of cross-well electromagnetic imaging logging system is introduced. The feasibility of numerical model matching （NMM） as forward method for cross-well logging system is researched. Through analysis of NMM＇s principle and the operation of the logging system, NMM can be simplified and written as program in parallel computation. The method is verified compared with analytical solution under uniform formation and horizontal layered one- dimensional formation. Then the method is also compared with integral equation and FEM under axial symmetry 2D non-uniform formation. The results show that the NMM for cross-well electromagnetic imaging logging system is feasible and improves the calculation speed significantly. However, the method used in long range logging demands more suitable radial basis function. We prove that the application of NMM in cross-well electromagnetic imaging logging system for the fast forward calculation has big development potential and great use prospect.