重力分异和非均质性对天然气藏CO_2埋存的影响——以中国南方XC气藏为例  

Influence of gravity differentiation and heterogeneity on CO_2 sequestration in gas reservoirs:A case of the XC Gas Reservoir in South China

作　　者：孙扬[1] 崔飞飞 孙雷[1] 杜志敏[1] 汤勇[1] 

机构地区：[1]西南石油大学 [2]中国石油南方石油勘探开发有限责任公司

出　　处：《天然气工业》2014年第8期82-86,共5页Natural Gas Industry

基　　金：中国石油"十二五"重大科技攻关项目"天然气开发关键技术研究"(编号:2011B-1507)

摘　　要：在含CO2的天然气藏中实施CO2长期稳定埋存并提高天然气采收率,实现CO2的规模化综合利用,具有重大的现实意义。为此,以一个真实的含CO2浅层废弃气藏为埋存靶场,运用数值模拟方法,设计了纵向非均质气藏剖面模型,用于研究气藏储层在正韵律、反韵律以及复合韵律条件下气体运移对超临界CO2稳定埋存的影响,并重点研究了重力分异和地层非均质性条件下的流体运移规律。结果表明:不同韵律剖面模型在注超临界CO2埋存及开采剩余天然气过程中,作为反韵律的目标气藏注超临界CO2埋存过程在生产井突破最晚,吸入的超临界CO2量最大,天然气累计采出量最多,其超临界CO2埋存潜力相对最大;重力分异可引起超临界CO2与天然气之间产生非平衡态相的分离,天然气向气藏高部位运移,CO2最终趋向于形成"超临界CO2垫气",可以很稳定地沉积在气藏下部形成"垫气"埋存。该成果为实现CO2减排、降低CO2捕集与埋存技术(CCS)成本提供了技术支撑。It is no doubt of great practical significance to implement the long-term stable CO2 sequestration in natural gas reservoirs containing CO2 , enhance gas recovery, and achieve large-scale utilization of CO2. In this paper, a real deserted shallow gas reservoir containing CO2 of XC in South China was taken as a case of study. Numerical simulation was first employed to design a model of lon- gitudinal heterogeneous gas reservoir profile to study the influence of gas migration under positive rhythm, reverse and composite rhythm conditions on the stability of supercritical CO2 sequestration. With focus on the fluid migration rules under gravity differentiation and formation heterogeneity, we concluded the following results. （1） Among different rhythm profile models in gas injection in supercritical CO2 sequestration and the exploitation of remaining natural gas, the target reservoir of reverse rhythm was the last one among which the supercritical COs sequestration was broken through in producing wells~ the absorbed volume of supercritical CO2 was the largest, and the cumulative gas production was the maximum, indicating that the potential supercritical CO2 storage volume might be the highest in that reservoir. （2） The gravity differentiation could cause the phases separation between supercritical CO2 and natural gas because of the non equilibrium phase behavior, the natural gas moved towards the upper area of a gas reservoir, and the supercritical CO2 eventually tended to form a ＂cushion＂ and was deposited steadily on the bottom of the reservoir. This study pro- vides a technical support for the minimization of CO2 emission and carbon capture and storage （CCS） cost.

关 键 词：二氧化碳 埋存 提高天然气采收率 重力分异 非均质性 反韵律 超临界 垫气 

分 类 号：P618.13[天文地球—矿床学]