Enhanced oil recovery in tight conglomerate reservoirs using CO_(2)flooding:A visual model with fractal-based zoningOA
CO_(2) flooding has emerged as a valuable method for enhancing oil recovery(EOR)in fossil fuel reservoirs.However,the impact of micro-heterogeneity,particularly variations in pore sizes,on CO_(2) flooding following water flooding in conglomerate reservoirs remains insufficiently understood.This study introduces an advanced visual model integrating outcrop and nuclear magnetic resonance(NMR)analyses to overcome the limitations of traditional micromodels.Simulating reservoir conditions,the model evaluates oil displacement and sweep efficiency through a fractal-based pore classification system,categorizing pores into four types:small pores(P1),medium pores(P2 and P3),and large pores(P4).This classification provides a comprehensive analysis of residual oil patterns during water and CO_(2) flooding.Results show that water flooding primarily displaces oil from larger pores(P3 and P4),leaving residual oil trapped in smaller pores(P1 and P2).After 0.4 PV injection,oil begins migrating from smaller to larger pores(P4),reaching an oil recovery efficiency of 28.91%at 0.8 PV.In contrast,CO_(2) flooding significantly expands the sweep area and improves displacement efficiency despite minor gas channeling.NMR analysis indicates that CO_(2) flooding rapidly mobilizes oil in large pores(P4),while its effect on smaller pores(P1 and P2)remains limited.The cumulative signal amplitude decreases from 2914 to 2498,resulting in a displacement efficiency of 10.15%and a total recovery factor of 39.06%.This study provides valuable insights into optimizing CO_(2) immiscible flooding strategies and improving oil recovery efficiency in tight conglomerate reservoirs.
Yuhao Lu;Jian Wang;Xiang Luo;Tianhan Xu;Danling Wang;Hongkun Wei
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,ChinaState Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,ChinaSchool of Petroleum Engineering,Xi''an Shiyou University,Xi’an,ChinaDAQING Oilfield of CNPC,Daqing,ChinaState Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,ChinaState Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,China
能源科技
CO_(2)floodingTight conglomerate reservoirsVisual outcrops modelOil mobilizationEnhanced oil recovery
《Petroleum》 2026 (1)
P.154-166,13
supported by the National Science and Technology Major Project for New Oil and Gas Exploration and Development,including the project titled Exploration and Development Technology and Integrated Demonstration of Paleogene Continental Shale Oil in Jiyang Depression,Bohai Bay Basin,3D Development Optimization Control and Enhanced Oil Recovery Technology(2024ZD1405103)the project titled CO_(2)Flooding for Improved Recovery and Long-Term Storage Technology,Research on Key Engineering Technology and Equipment of the Whole Process of CO_(2)Flooding and Storage(2024ZD1406603)supported by the National Natural Science Foundation of China(52174035).
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