三维磁性反演多约束控制子域迭代方法研究

Aimed at solving of the difficulties and problems in 3D magnetic inversion, we bring up a technical proposal named 3D inversion for magnetic properties with multi-constrained subspaces. Firstly, we employ subspace iteration strategy to solve the inversion problem in this proposal. This inversion strategy obviates the need to solve traditional difficult problems such as optimization methods equation solving, objective function derivation and constraints extraction. It also overcomes the problem of huge amount of calculation which is normally involved in nonlinear inversion methods. Secondly, multi-constraints are utilized to improve precision of the inversion result, including main anomaly constraint, repeated iteration constraint and source analysis extraction constraint. Thirdly, based on the phenomenon of associated positive and negative magnetic anomaly, we will do research on the theory of remanent magnetization and on inversion methods for it. Finally, by using new techniques of multi-plane subdivision and vertical interpolation, rapid magnetic forward computation can be achieved under the condition of undulating topography. Through this study, effective solutions of 3D magnetic inversion can be obtained which are intended for magnetic surface data under undulating topography and magnetic remanence data, and hence a solid theoretical foundation is laid for better effects of high-precision magnetic prospecting application.

针对磁异常三维磁性反演中存在的困难和问题，提出"三维磁性反演的多约束控制子域迭代方法"技术：1、采取子域反演法避免三维磁性反演中存在的最优化方法方程求解、目标函数求导、约束条件提取等困难；同时克服非线性方法中存在的维数困扰和巨大的计算量问题；2、采取主异常约束、二次迭代约束以及场源分析提取约束等技术措施，提高反演成像效果和精度；3、基于磁异常正负伴生以及反演结果场源的正负伴生现象，研究剩磁评价、识别与反演方法技术；4、针对起伏地形，采取多水平面分割、垂向插值的技术措施，可以实现起伏地形下快速直接磁性反演。通过该项研究，能形成面向起伏面积磁异常数据和具有未知剩磁特点的三维反演方法技术，为充分发挥高精度磁测的作用及其勘探应用效果提供技术理论基础。

重磁反演由二维到三维是发展的需要，其中三维磁性反演是重要方向之一。本研究针对磁异常三维磁性反演中存在的困难和问题，提出多约束控制迭代子域反演方法以及实现技术。结合研究内容和研究目标，开展相应方法技术研究并取得如下成果：.1、深化研究了随机子域反演算法，开展约束机制研究，结合子域反演方法，提出主异常约束，实现物性约束、深度权约束、主异常约束等多约束反演计算；.2、研究快速正演计算方法，提出起伏地形下三维物性快速正演方法，为起伏地形情况下的快速反演奠定基础；.3、开展了剩磁影响研究，实现了数据空间磁异常模量三维反演方法；.4、开展并行算法研究，实现随机子域反演算法多核并行计算；.5、开展了软件开发工作，设计开发了实用化软件。.通过本项目的研究，最终形成了适合起伏地形的磁异常三维磁性反演方法技术，该方法针对磁异常反演的特点，能更好地解决实际问题，具有理论和实用价值。