THE EFFECT OF SALINITY ON IN-SITU GENERATED CO_2 GAS: SIMULATIONS AND EXPERIMENTS

摘要

Carbon dioxide (CO_2) injection has been used as a commercial process for enhanced oil recovery (EOR) since the 1970's. Recently, a new in-situ CO_2 gas generation technology has been developed but not well studied. We conducted experiments to observe the dynamics of the system with different temperatures, injection sequences of chemical agents, chemical additives, and behavior of CO_2 generation with respect to these varying factors and comparison of the actual CO_2 pressure with the calculated values. Experiments on generation of CO_2 gas as a result of reactions of gas forming and gas yielding solutions were carried out. It is shown that the injection sequence of the chemicals affects the reaction characteristics, but the total amount of CO_2 gas generated does not vary significantly. Regardless of the injected solution (either gas forming or gas yielding) the maximum attainable pressures are less than the calculated pressures as a result of chemical equilibrium in the system; so this difference should be considered while calculating the size of the slug in the field applications. The brine concentration has an impact on CO_2 solubility in water and so on CO_2 pressure. Because of this impact, brine concentration of formation water should be considered in addition to the brine which is introduced to the system by the reaction.