2.5维复电阻率反演及其应用试验

自复电阻率法被提出以来,其区分矿与非矿方面的潜力就引起了人们的广泛关注,但反演问题一直没有得到较好的解决,已经严重影响和制约了该方法的应用和发展.对此,本文提出并实现了利用多个排列视电阻率和视相位数据的2.5维SIP联合反演方法.算法利用最小二乘原理构建了反演目标函数,为提高反演的稳定性,在反演方程中加入了Occam法的光滑模型约束.通过借助电场的偏导数形式,推导出了灵敏度矩阵的解析表达式,并应用互换定理对其进行精确求取.反演算法充分利用了电磁感应和激电效应中的异常信息,能够同时反演出二维地质断面上所有单元的四种复电阻率参数.最后,利用该反演程序对安徽某地区的SIP实测数据进行了反演成像,通过与已知钻井资料及CSAMT反演结果的对比分析表明,该反演算法具有良好的应用效果.

Research and application experiment on 2.5D SIP inversion

Complex resistivity method attracts people's great concern because of the potential in the distinction of ore and non-ore deposits since it was proposed. However, the inverse problem of SIP has not been resolved well, so it has restricted the application and development of SIP. Therefore, we proposed and implemented a 2.5D combined inversion method, which used multi-arrangement of apparent resistivity and apparent phase of SIP data. We established the inverse objective function by using least square principle, and used the smooth model of Occam method to improve the stability of inversion. We derived the analytical expression of the sensitivity matrix with the partial derivatives of the electric field, and calculated it with the reciprocity theorem. This method can perform large-scale inversion and take advantage of geological information that was contained in electromagnetic induction and IP effect. Finally, the inversion procedure was used in Anhui SIP measured data, and the result shows a good effect on application by comparison with known drilling data and CSAMT inversion result.