Summary Multifrequency complex electric measurements are influenced by the joint effects of mineralogy, spatial distribution of fluids and solids, properties of fluids and minerals, and interfacial polarization mechanisms. The interpretation of multifrequency electrical conductivity and dielectric permittivity dispersion can yield information about the dominant dielectric polarization mechanisms. The dielectric polarization mechanisms detected in sedimentary rocks are linked to grain size, shape, and orientation relative to the externally applied electric field, electrochemical adsorption/desorption complexation reactions, wettability, porosity, and fluid saturations. In this work, we introduce a new workflow for multifrequency interpretation of complex permittivity measurements. The introduced workflow enables simultaneous assessment of dominant wettability, porosity, and hydrocarbon reserves. These properties are estimated by minimizing a cost function using a combination of downhill gradient-descent and an evolutionary algorithm. The cost function quantifies the difference between measured and numerically calculated multifrequency complex dielectric permittivity through a recently introduced rock-physics model. We successfully applied the new interpretation workflow to multifrequency electrical resistivity/permittivity measurements obtained from two water-wet and two hydrocarbon-wet sandstone core samples. Simultaneous estimates of wettability, water saturation, and porosity obtained by applying the new interpretation workflow were in agreement with experimental measurements. Assessment of hydrocarbon reserves, porosity, and dominant wettability solely from the interpretation of multifrequency complex-valued electrical measurements is a unique contribution of the introduced workflow. Additionally, the new workflow honors rock fabric and, thus, it minimizes the necessity of extensive calibration efforts. All the parameters needed as inputs to the new interpretation workflow are associated with physical mechanisms at microscopic- and pore-scale domains or realistic and quantitative pore geometry features of the rock.

中文翻译：

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用于同时评估润湿性、孔隙率和水饱和度的复杂电导率测量的多频反演

总结 多频复合电测量受矿物学、流体和固体的空间分布、流体和矿物的性质以及界面极化机制的共同影响。多频电导率和介电常数色散的解释可以产生有关主要介电极化机制的信息。在沉积岩中检测到的介电极化机制与晶粒尺寸、形状和相对于外加电场的取向、电化学吸附/解吸络合反应、润湿性、孔隙度和流体饱和度有关。在这项工作中，我们介绍了一种新的工作流程，用于复杂介电常数测量的多频解释。引入的工作流程能够同时评估主要润湿性、孔隙度和碳氢化合物储量。这些属性是通过使用下坡梯度下降和进化算法的组合最小化成本函数来估计的。成本函数通过最近引入的岩石物理模型量化了测量和数值计算的多频复介电常数之间的差异。我们成功地将新的解释工作流程应用于从两个亲水和两个烃湿砂岩岩心样品中获得的多频电阻率/介电常数测量值。通过应用新的解释工作流程获得的润湿性、水饱和度和孔隙度的同时估计与实验测量结果一致。油气储量评估，孔隙度和主要润湿性仅来自对多频复值电测量的解释是所引入工作流程的独特贡献。此外，新的工作流程采用岩石结构，因此最大限度地减少了大量校准工作的必要性。作为新解释工作流程输入所需的所有参数都与微观和孔隙尺度域的物理机制或岩石的真实和定量孔隙几何特征相关。