一种改进的二维MT预条件非线性共轭梯度反演方法

摘要

Accuracy and cOmputatiOnal efficiency are cOnflicting tO each Other in MT inversiOn methOds. Gauss-NewtOn meth-Ods have high accuracy but pOOr efficiency, while nOnlinear cOnjugate gradient methOds are cOmputatiOnally efficient but less accurate. A new precOnditiOned nOnlinear cOnjugate gradient methOd is prOpOsed tO imprOve bOth accuracy and cOmputatiOnal cOst by using a precOnditiOn OperatOr whOse perfOrmance is apprOximated by Gauss-NewtOn Hessian matrix. A self-adapted al-gOrithm updating the regularizatiOn parameter is used tO guarantee the balance between the stability and the accuracy Of the inversiOn. ThrOugh the mOdel tests and cOmparisOns with Other methOds, the prOpOsed methOd is prOved achieving the gOal. The methOd is applied tO invert the MT data measured frOm a regiOn in west China. The inverted resistivity prOfile is cOnjOint-ly interpreted with seismic migratiOn prOfile, and illustrates its significance in cOmplicated structural interpretatiOn.%在大地电磁反演方法中反演精度与计算效率问题是一对矛盾，高斯牛顿类方法反演精度高但计算效率低，非线性共轭梯度类方法计算效率高，但是反演精度不如高斯牛顿法高。在前人研究的基础上，提出一种改进的预条件非线性共轭梯度法，通过构建性状更接近高斯牛顿Hessian矩阵的预条件算子提高反演精度和计算速度。同时采用正则化参数的自适应更新算法保证反演稳定性和反演精度的平衡。模型实验验证了该方法的正确性。与其他方法的对比结果表明，该方法在保证反演精度的同时，提高了计算效率。对中国西部某地的实测MT数据进行处理解释的结果表明，该方法在解决复杂构造问题方面具有较高的实用价值。