Change in reservoir rock pore volume due to pressure and temperature evolution of CO2 injection

ABSTRACT: Based on the theory of thermo-poroelasticity, the compressibility of pore volume Cpp has been reviewed and the thermal coefficient of porosity CpT has been introduced. Using typical curves of poro-elasticity parameters of sandstone versus porosity, the evolution of the parameters Cpp and CpT as function of porosity has been predicted. A parabolic curve of Cpp versus porosity has been obtained, with the minimum pore compressibility occurring at a porosity around 15% for sandstone. In the range of porosity, 8% ~ 20%, the pore compressibility is ±constant. The value of CpT is negative for sandstone, meaning that a decrease in temperature will increase the porosity, and conversely, an increase in temperature will decrease porosity. An advanced protocol of lab test has been put in place to directly and indirectly measure the parameters Cpp and CpT on a same sample. The calibration test using aluminum sample has demonstrated the high capacity of laboratory setup to operate under 1D strain condition while cycling of temperature and pressure.