Coupled geomechanic and fluid flow analysis is applied to develop theoretical and experimental background for geosteering and well logging to diagnose the state of near-wellbore formation and oil reservoir. The suggested methods of processing EM induction (VIKIZ) and Russian laterolog (RLL) resistivity responses account for effects of stress-dependent fluid flow changes. The geomechanic and fluid-flow effects on resistivity well logs are investigated for the case of asymmetric invasion and related irreversible deformation. Ways of taking into account stress-dependent effects on resistivity logs are developed on the basis of 3D modeling of geomechanic and electromagnetic fields.

The paper proposes a scheme of numerical experiment to assess the quality of interpretation of logging signals using a digital model of the oil reservoir, including geological, petrophysical, and physical parameters of the environment and interrelated modeling in the ATLAS MPhM system of physical processes occurring in the near-well space. The confidence intervals of oil saturation obtained as a result of interpretation of noisy synthetic logging curves for models with low and high resistivity are estimated.

SUMMARYATLAS is the collection of multiphysical models of the typical reservoirs of Western Siberia. Both geomechanical, hydrodynamic, geoelectric processes in the vicinity of the borehole and electrical and electromagnetic well logs are jointly analyzed. The influence of each of the hydrophysical and geomechanical parameters on the process of mud filtrate invasion into the formation, evolution of the electrical resistivity distribution in the borehole environment, the electric and electromagnetic logs can be studied and visualised by using ATLAS. Further development of ATLAS is aimed to creating interpreting system of the well geophysical and geological-technological studies on the basis of multiphysical reservoir models.

A subsystem for the search for a digital multiphysical model of the near–wellbore zone of reservoir layers has been created, which most closely matches the data known about the reservoir, including well logging data, as well as for the automated re–calculation of such models in the relational system for storing, searching, calculating electrical logging signals and visualization ATLAS MFM, developed at INGG SB RAS.