天然气工业2025，Vol.45Issue(9)：68-78,11.DOI:10.3787/j.issn.1000-0976.2025.09.006
碳酸盐岩有水气藏注CO2溶解、沉淀及运移机理
Mechanisms of dissolution,precipitation,and precipitate migration induced by CO2 injection in water-bearing carbonate gas reservoirs
摘要
Abstract
There are abundant carbonate gas reservoir resources in China,whose strong reservoir heterogeneity,common water bearing and active edge and bottom water,however,lead to low gas recovery factor.Enhancing the recovery of such gas reservoirs has long posed a significant challenge to the industry.CO2 injection into gas reservoirs,as a promising technology that can achieve significant gas recovery enhancement and carbon storage simultaneously(CCUS-EGR),is currently in the early research and pilot testing stages in China.To elucidate the dissolution,precipitation and precipitate migration mechanisms in CO2-water-carbonate rock system after CO2 injection into carbonate reservoirs,this paper carries out microscopic static dissolution experiments and dynamic displacement reaction experiments using experimental platforms such as high-temperature and high-pressure reactor and online displacement CT.The following results are obtained.First,CO2 dissolves in water to form carbonic acid fluid,which mainly reacts with dolomite and calcite in carbonate rocks.The dissolution reaction has greater influence on intracrystalline pores,and differential mineral dissolution leads to the formation of fractures within crystals,thereby enhancing pore connectivity.Second,in the process of dynamic displacement reaction,dissolution enlarges pore space and enhances connectivity,while precipitation reduces pore space or blocks pore throats.Dissolution coexists with the formation of precipitates.The formation of precipitates inhibits the dissolution on the affected surfaces,while the dissolution can reopen previously blocked pore throats.Third,the precipitates are mainly composed of calcium carbonate and magnesium carbonate,with calcium carbonate forming preferentially.Calcium carbonate typically appears in blocky or clustered shape,while magnesium carbonate tends to be flocculent or petal shaped.Fourth,the migration of precipitates is influenced mainly by gravity and hydrodynamic forces.In small pores,hydrodynamic force has greater influence,and precipitates migrate along fluid flow direction to accumulate at the throat outlet.As pore size increases,hydrodynamic force diminishes gradually.And when gravity becomes the dominant factor,the precipitates migrate along the gravity direction to deposit.In conclusion,this systematic experimental study from static to dynamic conditions illustrates the evolution characteristics of geometric shapes of pore space in the micro scale,and reveals the mechanisms of dynamic dissolution,precipitation,and precipitate migration induced by CO2 injection in water-bearing carbonate gas reservoirs,so as to provide theoretical support for deeply investigating the microscopic evolution mechanisms of reservoir physical properties under the effect of CO2-water-carbonate rock interaction.关键词
碳酸盐岩气藏/CCUS-EGR/微观反应机理/溶解/沉淀/运移Key words
Carbonate gas reservoir/CCUS-EGR/Microscopic reaction mechanism/Dissolution/Precipitation/Migration分类
能源科技引用本文复制引用
赵玉龙,汪永朝,文绍牧,位云生,张烈辉,黄兰,曹成..碳酸盐岩有水气藏注CO2溶解、沉淀及运移机理[J].天然气工业,2025,45(9):68-78,11.基金项目
国家自然科学基金区域联合基金重点项目"四川盆地有水气藏CO2驱提高采收率及其有效封存研究"(编号:U23A2022)、国家自然科学基金面上项目"致密砂岩气藏注CO2增压驱替—竞争吸附—改善渗流协同提采与封存机理研究"(编号:52474047). （编号:U23A2022）
