Pore-scale evaluation of CO2 miscible displacement in porous rocks induced by convection and diffusion:implications for CO2 geo-sequestration
Xiangjie Qin1
Han Wang1
Jinsui Wu2
Gang Wang3
David A.Wood4
Jianchao Cai1
1.State Key Laboratory of Petroleum Resources and Engineering,China University of Petroleum,Beijing 102249,China2.Department of Management Science and Engineering,Khalifa University,127788,Abu Dhabi,United Arab Emirates3.College of Safety and Environmental Engineering,Shandong University of Science and Technology,Qingdao 266590,China4.DWA Energy Limited.Lincoln LN5 9JP,UK
摘要：CO2 enhanced oil recovery plays an important role in carbon storage and utilization.However,the incomplete understand-ing of the underlying microscopic convection-diffusion mechanisms in complex pore structures has constrained the broader industrial application of CO2 geo-sequestration.This work develops a pore-scale numerical model considering molecular convection-diffusion to investigate CO2-oil miscible displacement in two-and three-dimensional porous structures of con-glomerate rocks.The effects of CO2 injection rates and pore structure properties on convection-diffusion are analyzed.By reconstructing the distribution of unexploited pores,the CO2 sweep efficiency is quantitatively evaluated.Furthermore,a sequestration factor is proposed to evaluate the CC2 storage capacity during miscible displacement.Convection significantly enhances the CC2 mass fraction in fractures with high flow rates.Subsequently,CO2 gradually diffuses into matrix pores without velocity distribution.Both convection and diffusion contribute to improving CO2 displacement efficiency.Diffusion facilitates the dissolution of CO2 into oil within small-diameter pores,and convection effectively mobilizes oil in large pore bodies.Developed and homogeneous pore structures enhance CO2 displacement efficiency,whereas CO2 flows along the main flow channels in heterogeneous pore structures,resulting in lower displacement efficiency.Diffusion plays a crucial role in CC2 storage within porous media.At low injection rates,dissolved CO2 is trapped in poorly connected and blind-end pores.The injection rate is negatively correlated with the sequestration factor.
机标关键词：convectionevaluationdiffusionrocksdisplacementimplicationsinducedmiscible
论文发表日期：2025-08-31
在线出版日期：2026-01-30（本平台首次上网日期，不代表文献的发表时间）
页数：19( 71-89 )
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