Variation of petrophysical properties due to carbon dioxide (CO2) storage in carbonate reservoirs

摘要

Depleted hydrocarbon reservoirs, deep saline reservoirs, and un-mineable coal seams are considered the best geological sequestration candidates for carbon dioxide (CO2) geologic storage formations. CO2sequestration in carbonate reservoirs provides a good way to reduce CO2release to the atmosphere. This work investigates the effect of the temperature, pressure, and brine salinity on the petrophysical changes in the carbonate cores due to CO2storing. Two groups of experiments were undertaken; (1) investigating the CO2solubility under different salinities, pressures and temperatures, and (2) studying the effect of CO2storage duration on porosity and permeability of carbonate rocks. Actual cores saturated with 25 000 ppm NaCl brine were used. The potential of the CO2storage capacity and variations in porosity and permeability are evaluated and quantified. The results showed that solubility of CO2decreases with increase in brine salinity and/or temperature. The increase of pressure causes an increase in CO2solubility. The results also indicated that storing CO2more than 150 days increases the porosity and permeability of carbonate rocks. The application of the achieved results is expected to have good impact on design storage process of CO2in deep saline water incarbonate reservoirs, and on validation of developed mathematical models.