Comparison of Analytical and Experimental Methods for Determining Dependency of Permeability of Clayey Sandstones on Effective Pressure

This study examines permeability changes in terrigenous reservoir rocks under varying effective pressures using laboratory experiments and analytical models. Core samples of fine-grained sandstones with clay cement were subjected to control triaxial compression tests and permeability measurements under simulated reservoir conditions. The experimental results showed that increasing effective pressure causes significant permeability reductions due to pore volume contraction, plastic deformation, and clay swelling. Furthermore, the permeability loss was found to be irreversible, as the samples did not regain their original characteristics after unloading. Analytical models incorporating elastic properties, including Young’s modulus and Poisson’s ratio, demonstrated the influence of fluid saturation, effective pressure, and porosity on permeability changes. A comparative analysis of experimental and analytical methods revealed their respective advantages and limitations. The study highlights the importance of preserving natural saturation during core sampling and recommends reservoir pressure maintenance systems to mitigate permeability loss. These findings provide critical insights for optimizing the development and management of oil fields with clayey reservoir rocks.