Hydrocarbon Reserves Evaluation in Anisotropic Formations with Complex Composition and Pore Geometry using Electrical Measurements

In this presentation, the effects of complex pore structure, rock fabric, and directional connectivity of kerogen, pyrite, and pore networks on electrical properties of organic-rich mudrock and carbonate examples will be discussed. Furthermore, a new analytical model will be introduced for assessment of water-filled porosity and hydrocarbon saturation that takes into account rock fabric. The results of numerical simulations show that (a) the directional connectivity of mature kerogen network has measurable impact on directional electrical resistivity of the rock and the corresponding estimates of fluid saturation and (b) pyrite's presence, even in low concentrations, and its directional connectivity affect electrical resistivity and dielectric permittivity of the rock. Neglecting the presence of kerogen and pyrite can result in up to 18% and 23% underestimation of hydrocarbon saturation, respectively. Laboratory experiments of electrical properties complement numerical simulations by estimating model input parameters and validating the assumptions. The results also confirm the importance of taking into account rock fabric and directional connectivity of conductive rock components in upscaling of electrical properties in anisotropic rocks.

Speaker: Zoya Heidari, Univ. of Texas