Performance evaluation of newly developed true triaxial stress loading and pore pressure applying system to simulate the reservoir depletion and injection

A new true triaxial stress loading and pore pressure applying apparatus (TTSL-PPAA) has been designed and fabricated for testing relatively large rock specimens under high-stress levels and pore fluid pressures. The system has the capability of simultaneously monitoring the stresses and strains in three principal stress directions, applied pore pressures, and flow rate of depletion and injection fluids. The apparatus is specially designed to simulate depletion/ injection processes of the reservoir under TTSL and uniaxial strain or constant stress boundary conditions. The depletion/injection simulations are being used to study the in situ stress changes and consequently reservoir compaction induced by fluid production and injection. Knowledge of in situ stress variations with reservoir pore pressure depletion and injection is important in a multidisciplinary approach for accurate reservoir characterization, optimal reservoir management, and enhanced oil recovery projects. In addition to depletion/injection tests, the developed system has the potential to be used in different geomechanical investigations such as stress–strain experiments, permeability assessment, wellbore stability studies, hydraulic fracturing simulations, and sand production tests. The TTSL-PPAA permits mechanical testing of rock specimens of up to 30 cm in size and hydro-mechanical testing at the presence of high pore pressure on specimens of up to 15 cm in dimension. The reliability and effectiveness of the newly developed apparatus were checked by different testing programs and numerical modeling. This manuscript describes the design, development, performance evaluation and preliminary use of the developed TTSL apparatus for petroleum related geomechanics investigations, especially for the depletion/injection simulations.