Enhanced gas recovery with CO2 sequestration: The effect of medium heterogeneity on the dispersion of supercritical CO2-CH4
Enhanced gas recovery with CO2 sequestration: The effect of medium heterogeneity on the dispersion of supercritical CO2-CH4
复制标题
DOI：
10.1016/j.ijggc.2015.04.014
复制
发表时间：
2015-08
影响因子：
3.9
通讯作者：
A. Honari;B. Bijeljic;M. Johns;E. May
中科院分区：
文献类型：
--
作者：
A. Honari;B. Bijeljic;M. Johns;E. May
将CO2回注到正在生产的天然气藏中，被认为是提高天然气采收率、减少大气排放和控制气候变化的一项有前途的技术。然而，天然气和CO2在储层条件下是可混溶的，并且可能导致采出天然气的CO2污染。这种混合过程以及因此提高天然气采收率（EGR）项目的可行性可以通过油藏模拟来定量确定-这种模拟需要描述气体分散。在这里，我们通过碳酸盐岩和砂岩岩心在各种油藏条件下进行流体输运实验，以评估超临界CO2和CH 4之间的分散介质非均质性的影响，占错误的贡献从入口/出口和重力效应。早期突破和长尾配置文件观察到的碳酸盐岩芯（Ketton），这是由于存在的晶粒内微孔，这导致在一个持久的前渐近传输制度。因此，一个修正的模型（移动-不动模型）被成功地用于这个核心，以获得最终的渐近制度的色散系数特性。所考虑的两种非均质碳酸盐岩都表现出比在先前测量的均质砂岩岩心中观察到的更高的分散度（Honari等人，2013年）的报告。幂律描述了在相对较高的间隙位移速度下弥散系数对Péclet数的依赖性，给出了砂岩的指数为1.2，碳酸盐岩的指数为1.4，与文献预测一致（Bijeljic和Blunt，2006年; Bijeljic等人，2011）基于孔隙尺度模拟。
Reinjection of CO2into producing natural gas reservoirs is considered as a promising technology to improve gas recovery, mitigate atmospheric emissions and control climate change. However, natural gas and CO2are miscible at reservoir conditions and could result in CO2contamination of produced natural gas. This mixing process and consequently the viability of Enhanced Gas Recovery (EGR) projects can be quantitatively determined by reservoir simulations – such simulations require a description of gas dispersion. Here we conduct fluid transport experiments through carbonate and sandstone rock cores at various reservoir conditions to evaluate the effect of medium heterogeneity on the dispersion between supercritical CO2and CH4, accounting for erroneous contributions from entrance/exit and gravitational effects. Early breakthrough and long-tailed profiles are observed for one of the carbonate cores (Ketton) which is attributed to the existence of intra-grain micro-pores, which results in a persistent pre-asymptotic transport regime. Thus a revised model (Mobile-Immobile Model) was successfully used for this core to obtain dispersion coefficients characteristic of the eventual asymptotic regime. Both heterogeneous carbonate rocks considered exhibit higher dispersion than that observed in previously-measured homogeneous sandstone cores (Honari et al., 2013). The power law describing the dependency of dispersion coefficient on Péclet number at comparatively high interstitial displacement velocities gave an exponent of 1.2 for sandstones and 1.4 for carbonates, consistent with literature predictions (Bijeljic and Blunt, 2006; Bijeljic et al., 2011) based on pore-scale simulations.