Resistivity numerical simulation and its influence law analysis based on multi-component 3D digital core of glutenite

Due to the strong non-homogeneity and complex pore structure of glutenite reservoirs， it isn’t easy to accurately reflect the oil content of the reservoir through resistivity response. However， the traditional two-component three-dimensional （3D） digital core modeling and numerical simulation method of resistivity fail to characterize the multi-component and multi-scale pore space and accurately simulate the resistivity of the glutenite. The deep glutenites of the upper Submember of the 4th Member of the Paleogene Eocene Shahejie Formation （Es4U） in the northern steep slope zone of Dongying Sag were studied， as well as the plunger samples of Well Yan 22-22 in Yanjia Oilfield. The conventional core analysis， nuclear magnetic resonance （NMR） test， X-ray computerized tomography （X-CT） scanning， modular automated processing system （MAPS） test， and quantitative evaluation of minerals by scanning electron microscopy （QEMSCAN） were performed to establish a multi-component 3D digital core of glutenite. The numerical simulation method of resistivity was adopted to analyze the influence of reservoir parameters on the resistivity characteristics of the glutenite. The results show that ① X-CT scanning is used to scan the standard plunger samples， and the multi-threshold segmentation is performed to distinguish the main mineral components to establish a multi-component 3D digital core of the glutenite. The main components match with the results of X-ray diffraction （XRD） tests of the samples， but the identified porosity is much lower than the gas porosity measured of the core due to the limitation of the scanning resolution. ② The two-dimensional （2D） images established by the MAPS test with 100 nm and 10 nm resolution are selected to calculate the microporosity of the main mineral components， which is combined with the component content of the 3D digital core to calculate the total porosity of the multi-component 3D digital core of the glutenite， which matches with the gas porosity measured of the core. ③ The numerical simulation results of resistivity show that the influence of gravel and clay mineral content on the resistivity of glutenite is not monotonous. The influence of gravel content is related to sample sorting， and that of clay mineral content is related to the type of clay and the salinity of the formation water.