Home – Home – Jornals – Russian Geology and Geophysics 2018 number Неопубликованное

The article presents algorithms for numerical modeling of electrical micrologging signals and calculation results in geoelectric models of impermeable rocks and the borehole environment of a porous, permeable reservoir. This research may be useful for developing an integrated approach to the quantitative interpretation of electrical logging data. A joint numerical analysis of electrical logs measured by conventional probes and microprobes will enable refining the radial electrical resistivity distribution in the borehole environment of oil-gas reservoirs. This, in turn, will provide additional information when jointly solving the problem of drilling mud filtration and numerical inversion of electrical logging data, resulting in a more accurate assessment of reservoir porosity and permeability. We have developed software for numerical simulation of electrical micrologging signals – those from a microgradient, micropotential and microlaterolog probe with focusing. We employ a finite element algorithm with an arbitrary position of the probes in a cylindrically-layered geoelectric model, and a finite difference algorithm for a microgradient and micropotential probe in a horizontally-layered model. Test calculations of the signals in geoelectric models of Western Siberia terrigenous deposits are presented. The models describe impermeable sediments as well as layers with the mud cake and invaded zone at different resistivity ratios. The model parameters correspond to Lower Cretaceous oil-gas reservoirs exposed with polymer-clay drilling muds. The analysis of the calculated micrologging signals reflects a small investigation depth of microgradient and micropotential probes, and a strong dependence of the signals on the drilling mud and mud cake resistivities. Numerical modeling in the class of a cylindrically-layered model has allowed us to obtain the radial resistivity change in the borehole environment of an oil-gas reservoir.