Laboratory core flooding experiments in reservoir sandstone under different sequestration pressures using multichannel fiber Bragg grating sensor arrays

This paper describes an innovative method for a fiber-optic sensing technology based on multichannel fiber Bragg grating (FBG) sensor arrays, which was applied to deionized water and free-CO2 core flooding experiments on saturated Shaximiao sandstone core specimens under various sequestration pressures. Three FBG sensor arrays, bonded to the sandstone surface along the axial and radial directions, dynamically monitored the strain responses during the wetting phase (water) or non-wetting phase (CO2) displacement processes. It was found that with the increase in the confining pressure or pore pressure, the relative strain increased throughout the experiment. For the water flooding experiment, the proportions due to rise the sequestration pressures are different in each scenario and FBG arrays, and they are generally positive increase, which can also be ascribed to the effective pressure. Meanwhile, the initial arrival time of the precisely characterized strain histories revealed the fronts of the injected water as well as the detailed implications of the CO2 plume migration during the core-scale flooding process. These FBG data from water/CO2 flooding experiments are of great significance for geophysicists and reservoir engineers to better establish the accumulations of raw data and theoretical mechanism reserves for further experimental analysis, numerical simulation and field applications in the CCUS projects and can enhance the minimal experimental data available in the literature to provide a new data set in the geomechanical field for water-CO2 two-phase fluid flow.