考虑激电效应的瞬变电磁三维OCCAM-LBFGS反演研究

The chargeability parameter can be recovered from transient electromagnetic (TEM) induced polarization (IP) data. In our country, the chargeability parameter plays an important role in the field of energy exploration, hydraulic and environmental detection and monitoring, etc. However, the field TEM data lack of 3D IP inversion technique. Based on the Cole-Cole model in time-domain, the time-domain finite difference method is used in the 3D forward modeling in this project. Based on the LBFGS inversion method and regularization factor searching idea of OCCAM method, a novel OCCAM-LBFGS inversion method which can reduce computer memory requirement, promote the stability of the inversion convergence and improve computation efficiency is developed. A new approach that can reduce the uniqueness is proposed and applied in the 3D IP inversion of TEM data. 3D forward and inversion parallel algorithm are implemented. This 3D effective and practical inversion algorithm can be used to invert TEM IP field data and promote the application of TEM in the resource exploration field and so on.

瞬变电磁的实测数据包含激电效应信息，从激电效应信息中提取出的极化率等参数在我国能源勘探、水文与环境探测与监测等领域具有重要的作用。然而，瞬变电磁的数据反演缺乏实用化的考虑激电效应的三维反演技术。本项目拟采用时域有限差分法和时域Cole-Cole模型直接在时间域中实现考虑激电效应的瞬变电磁三维正演。基于有限内存拟牛顿（LBFGS）反演方法和OCCAM最优权重因子搜索思路构建出一种节约内存、提高反演收敛稳定性和计算效率的OCCAM-LBFGS反演方法，实现考虑激电效应的瞬变电磁三维反演，同步反演4个激电模型参数。并且提出一种新的减小反演多解性的方案，应用于激电多参数的三维反演。同时开展三维正反演并行计算，形成高效率、实用化的考虑激电效应的瞬变电磁三维正反演技术，提高瞬变电磁法在能源勘探等领域的应用效果。

瞬变电磁在我国能源勘探、水文与环境探测与监测等领域具有重要的作用。然而，瞬变电磁的数据处理手段缺乏实用化的考虑激电效应的三维反演技术。本项目采用时域有限差分法离散考虑激电效应的时域麦克斯韦方程实现了三维正演。与AarhusInv代码的计算结果对比验证了所实现三维正演算法的精度。基于有限内存拟牛顿（LBFGS）反演方法和OCCAM最优权重因子搜索思路的方法，实现了同步反演4个激电模型参数的OCCAM-LBFGS三维反演。理论模型合成算例的计算结果验证了所实现三维反演算法的可靠性和稳定性。用三维反演算法程序对新疆哈密地区银帮山-寨北山铜矿区实测资料进行了反演，反演结果验证了所实现的考虑激电效应的瞬变电磁三维反演算法的有效性和实用性，能够提高瞬变电磁法在能源勘探等领域的应用效果。