基于改进差分进化算法的大地电磁测深和重力宽范围物性约束联合反演

Joint inversion of magnetotelluric and gravity based on improved differential evolution algorithm and wide-range petrophysical constraints

宽范围物性约束技术容易实现、具有一定容错性,目前已在大地电磁测深(MT)和地震、MT和重力联合反演中实现,但该技术是结合模拟退火算法实现的.差分进化算法(DE)是一种全局优化算法,但该算法在地球物理联合反演领域应用较少.基于此,本文以双种群设置方案为框架改进了DE算法,并提出了基于改进DE算法的宽范围物性约束技术.MT和重力联合反演的模型试验表明:与传统的DE算法相比,改进的DE算法收敛速度更快,寻优能力更强;基于改进DE算法的宽范围物性约束技术可以促进不同岩石物性参数在一定“范围”内实现耦合,既可以利用岩石物性关联的导向作用,又可以发挥优化算法的寻优能力,进而降低地球物理联合反演对先验信息的要求;此外,该技术的实现也验证了宽范围物性约束思想在联合反演领域中的适用性,具有进一步推广至其他优化算法中的潜质.

The wide-range petrophysical constraints technique implemented in joint inversions of magnetotelluric(MT)and seismic,MT and gravity,has advantages of easy implementation,and certain fault tolerance.However,the technique is realized based on simulated annealing algorithm.In addition,differential evolution(DE)algorithm is a global optimization algorithm while it is seldom used in geophysical joint inversions.Based on this,we improve the DE algorithm based on the two-population scheme,and propose the wide-range petrophysical constraints technology using the improved DE algorithm.Model tests of MT and gravity joint inversion show that the improved algorithm has a faster convergence speed and higher optimization capability than the traditional one.Besides,the wide-range petrophysical constraints technique using the improved DE algorithm can promote the coupling of different model parameters within a certain“range”.It can develop the guiding role of rock physical property correlation,and can also exert the optimization ability of the optimization algorithm,reducing the prior information requirement for a joint inversion.Moreover,the implementation of the technique also verifies the applicability of the idea of wide range of physical constraint in the field of joint inversion,which has the potential to be further extended to other optimization algorithms.