An experimental study for the effect of CO2-brine-rock interaction on reservoir physical properties

To study the variations of reservoir physical properties, micro-pore structure and permeability after CO2 injection, a core flooding laboratory equipment was used to simulate the CO2-brine-rock interaction during CO2 flooding process under different pressure and different temperature conditions. Analysis of the data from air permeability, water-phase permeability, intrusive mercury curve, core scanning electron microscope (SEM) and bulk-rock X-ray diffraction (XRD) states that after the experiment, the carbonate minerals were corroded strongly, followed by feldspar, with quartz to be the weakest one. The secondary minerals generated include calcite, ankerite, hematite, albite, etc. And illite and chlorite in the clay minerals were partially conversed to kaolinite. Corrosion, secondary minerals and precipitate optimized the sorted behavior of rock throats and lowered the permeability. With the increasing reaction pressure and temperature, rock corrosion and precipitation intensified, the permeability decreased gradually and the displacement pressure increased.