基于阿尔奇公式的三维直流电阻率有限元正演

Three-Dimensional DC Finite Element Orthogonal Simulations Based on the Archie Formulation

关键词:  直流电阻率  阿尔奇公式  有限单元法  数值模拟

Key words:  Archie Formula  DC Resistivity Method  Finite Element Method  Numerical Simulation

摘要:

本文通过引入阿尔奇公式,实现了适用于渗流条件的三维直流电阻率有限元正演。采用非结构四面体网格进行区域离散,以准确刻画地质模型；通过阿尔奇公式建立孔隙度、含水饱和度等参数与岩石电阻率的内在联系,构建渗流场的多参数模型；以典型砂岩型模型与砂岩型油水模型为例开展了一系列的数值模拟,分析了不同阿尔奇参数条件下的正演视电阻率响应规律。数值模拟结果表明,孔隙度、含水饱和度、胶结指数以及溶液电阻率对三维直流电正演响应的影响不容忽视；基于阿尔奇公式相关参数与视电阻率影响规律分析,为深入研究渗流场提供参考。

Abstract:

In this paper, a three-dimensional DC resistivity finite element orthotropy applicable to seepage conditions is realised by introducing the Alchy formula. The unstructured tetrahedral mesh is used to discretize the area in order to accurately portray the geological model; the intrinsic connection between parameters such as porosity, water saturation and rock resistivity is established through the Algebras formula to construct a multi-parameter model of seepage field; a series of numerical simulations are carried out using a typical sandstone-type model and a sandstone-type oil-water model as examples, and the orthorectified apparent resistivity response law is analysed under the conditions of different Algebras parameters. The numerical simulation results show that the effects of porosity, water saturation and cementation index, solution and surrounding rock resistivity on the 3D DC positive response should not be neglected; based on the analysis of the influence law of the relevant parameters and apparent resistivity of the Algebras formula, it can provide a reference for the in-depth study of the seepage field.