澳门银河赌场注册送38-澳门银河赌场招人好招吗_百家乐德州_全讯网下载 (中国)·官方网站

When low-salinity water containing sulfate ions is injected into carbonate reservoirs, rock dissolution and in situ precipitation occur, altering rock permeability and wettability. Particularly, when barium ions are present in formation water, they react chemically with SO^2-₄ , and BaSO₄ is precipitated. These reactions can cause a serious impact on the efficiency of enhanced oil recovery (EOR). Therefore, the main purpose of this study was to identify EOR efficiency induced by lowsalinity waterflooding (LSWF) when Ba²⁺ is present in carbonate reservoirs. From the experimental results, it was confirmed that the permeability calculated by the measured pressure difference was improved because of rock dissolution predominating over in situ precipitation for the case of low Ba²⁺ concentrations. In the analysis of wettability alteration through the measurements of relative permeabilities before and after LSWF, the higher Ba²⁺ concentration case consumed more SO^2-₄ in precipitating the BaSO₄, resulting in weaker wettability alteration due to the reduction of sulfate activity. These phenomena ultimately influenced EOR efficiency, i.e., the oil recovery was greater for the lower Ba²⁺ concentration.