首页|致密砂岩气藏注CO2提高天然气采收率微观机理

致密砂岩气藏注CO2提高天然气采收率微观机理

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  • 国家科技期刊平台
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中国致密砂岩气藏资源储量丰富,复杂的气水渗流关系和气水同产特征制约了单井产能的发挥和天然气采收率提高,注CO2 是提高气藏采收率(EGR)和实现碳埋存的双赢途径.为明确致密砂岩气藏CO2 驱替微观渗流和提高天然气采收率机理,指导致密砂岩气藏CO2-EGR方案设计,基于格子玻尔兹曼方法(LBM)建立了孔隙尺度多相多组分流动模型,揭示了致密砂岩气藏储层微观气水分布特征和CO2-EGR的微观渗流机理,并明确了CO2-EGR的主控因素.研究结果表明:① 驱动压差显著影响了致密砂岩气藏的气水微观分布和水锁程度,使得气水流动能力和气水相对渗透率特征不同;② CO2-EGR微观渗流过程包括气水两相的非混相驱替和CO2-CH4 的混相驱替,对应EGR机理为分别受生产压差和地层压力控制的黏性驱替和混相扩散;③ 注入的CO2 可有效缓解水锁现象和贾敏效应,与CH4 良好的混相能力能促进沟通分散气泡,微观驱气效率可达 42%～94%;④ 含水饱和度、孔隙结构和驱动压差显著影响微观驱气的作用机制和驱气效率的改善幅度.结论认为,在进行致密砂岩气CO2-EGR的方案设计时,可优先考虑中—低含水饱和度的区块作为试验靶区,并根据靶区储层孔隙结构特征,优化不同注气阶段的注采参数,可充分发挥CO2 对CH4 的黏性驱替和混相扩散作用.
Microscopic mechanism of CO2 injection to enhance gas recovery in tight sandstone gas reservoirs
Tight sandstone gas reservoirs in China have abundant natural gas reserves,but the complex gas-water flow relationships and the co-production of gas and water restrict the exertion of single well productivity and the improvement of natural gas recovery factor.CO2 injection is a promising dual-benefit approach to enhancing gas recovery(EGR)and achieving carbon storage.In order to clarify the microscopic flow and EGR mechanisms of CO2 flooding in tight sandstone gas reservoirs and guide the design of tight sandstone gas CO2-EGR scheme,this paper establishes a pore-scale multiphase and multicomponent flow model based on lattice Boltzmann method(LBM),reveals the microscopic gas and water distribution characteristics of tight sandstone gas reservoirs and the microscopic flow mechanisms of CO2-EGR,and finally clarifies the main control factors of CO2-EGR.And the following research results are obtained.First,the displacement pressure difference significantly affects the microscopic gas and water distribution and water blocking degree in tight sandstone gas reservoirs,resulting in various gas and water flow capabilities and relative permeability characteristics.Second,the microscopic flow process of CO2-EGR includes gas-water immiscible displacement and CO2-CH4 miscible displacement,whose corresponding EGR mechanisms are viscous displacement and miscible diffusion,controlled by production pressure difference and formation pressure respectively.Third,the injected CO2 can effectively alleviate water blocking and Jamin effect,and its good miscibility with CH4 promotes the communication of dispersed gas bubbles,which results in a microscopic gas displacement efficiency of 42%to 94%.Fourth,water saturation,pore structure and displacement pressure difference significantly affect the mechanism and performance of microscopic gas displacement efficiency.In conclusion,when designing the CO2-EGR scheme for tight sandstone gas,priority shall be given to the reservoir with low to medium water saturation as the test target area,and the injection and production parameters of different gas injection stages shall be optimized according to the pore structure characteristics of the reservoir in the target area,so as to give full play to the viscous displacement and miscible diffusion of CH4 by CO2.

Tight sandstone gas reservoirCO2 enhanced gas recoveryLattice Boltzmann methodMicroscopic gas displacement efficiencyPore scaleMultiphase and multicomponent

朱清源、吴克柳、张晟庭、程诗颖、王田多奕、刘琦琦、李靖、陈掌星

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油气资源与探测国家重点实验室·中国石油大学(北京)

卡尔加里大学化学与石油工程系

致密砂岩气藏 注CO2 提高气藏采收率 格子玻尔兹曼 微观驱气效率 孔隙尺度 多相多组分

国家自然科学基金项目&&&&北京市自然科学基金项目

5217404152104051518743193232029

2024

10.3787/j.issn.1000-0976.2024.04.014

天然气工业
四川石油管理局 中国石油西南油气田公司 中国石油川庆钻探工程公司

天然气工业

CSTPCD北大核心EI
影响因子：2.298
ISSN：1000-0976
年,卷(期)：2024.44(4)
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