Modeling of Thermal Gas Treatment of Low-Permeability Reservoirs of Bazhenov Formation

A coupled compositional and geomechanical model is presented which is applicable to simulation of thermal gas treatment of Bazhenov formation. The geomechanical module includes the criteria for rock fracturing caused by the increase in the internal pore pressure due to pyrolysis (decomposition) of solid organic material, kerogen, with formation of synthetic oil and gases, criteria for the formation of hydraulically connected system of cracks, as well as models for the permeability of fractured rock. Numerical simulations are performed for the scheme of air injection into high-permeability layers available in the impermeable kerogen-containing matrix. It is shown that straightforward technological scheme using the same permeable layer for air injection and oil production may not be viable because the cracked zone is lags behind the in-situ combustion front propagation, and synthetic oil may be burnt in the injected air, rather than reach the production well.