To study the injection process of CO2-hydrocarbon gas mixtures in shale oil and understand the impact of various parameters and the fluid production degree in nano-micron-sized pore throats, nuclear magnetic resonance (NMR) experiments were conducted to reveal the huff-n-puff characteristics such as changes in final recovery, T2 distribution curves, and the mobilization of crude oil in different pore sizes during injection, and explain the effects of gas mixture type, injection method, and total organic carbon (TOC) on the huff-n-puff efficiency. The results show that CO2 + C3H8, compared with CO2 + CH4, has stronger miscibility with crude oil. Under the same gas injection pressure conditions, the final recovery of CO2 + C3H8 huff-and-puff can be increased by 3.21 percentage points, with C3H8 contributing more to shale oil recovery. Combining the strong compressibility of CO2 + CH4 and the strong miscibility of CO2 + C3H8, injecting CO2 + CH4/CO2 + C3H8 can effectively produce crude oil in large, medium, and small pores of the shale, with the final recovery reaching 28.97 percentage points. As TOC of the shale increases, more crude oil is adsorbed and dissolved during saturation, reducing recovery but increasing gas mixtures diffused into kerogen. This study provides a theoretical basis for the field implementation of huff-n-puff injection of CO2-hydrocarbon gas mixtures in shale oil.
PAN Xianggang
,
WANG Qijun
,
CHEN Hua
,
CHENG Yunlong
,
YU Qiangang
,
HUO Jiahua
,
LI Xin
. Experimental study on huff-n-puff of CO2-hydrocarbon gas mixtures in shale oil[J]. Special Oil & Gas Reservoirs, 2025
, 32(3)
: 104
-110
.
DOI: 10.3969/j.issn.1006-6535.2025.03.012
[1] 袁士义,雷征东,李军诗,等.陆相页岩油开发技术进展及规模效益开发对策思考[J].中国石油大学学报(自然科学版),2023,47(5):13-24.
YUAN Shiyi,LEI Zhengdong,LI Junshi,et al.Progress in technology for the development of continental shale oil and thoughts on the development of scale benefits and strategies[J].Journal of China University of Petroleum(Edition of Natural Sciences),2023,47(5):13-24.
[2] JIA B,TSAU J S,BARATI R.A review of the current progress of CO2 injection EOR and carbon storage in shale oil reservoirs[J].Fuel,2019,236:404-427.
[3] TORABI F,ASGHARI K.Effect of operating pressure,matrix permeability and connate water saturation on performance of CO2 huff-and-puff process in matrix-fracture experimental model[J].Fuel,2010,89:2985-2990.
[4] GAMADI T D,SHENG J J,SOLIMAN M Y.An experimental study of cyclic CO2 injection to improve shale oil recovery[J].Fuel,2013,79:1385-1390.
[5] PENG Xiyi,WANG Yanyong,DIAO Yuqian,et al.Experimental investigation on the operation parameters of carbon dioxide huff-n-puff process in ultra low permeability oil reservoirs[J].Journal of Petroleum Science and Engineering,2018,39(7):1-14.
[6] 郎东江,伦增珉,吕成远,等.页岩油注二氧化碳提高采收率影响因素核磁共振实验[J].石油勘探与开发,2021,48(3):603-612.
LANG Dongjiang,LUN Zengmin,LYU Chengyuan,et al.Nuclear magnetic resonance experimental study of CO2 injection to enhance shale oil recovery[J].Petroleum Exploration and Development,2021,48(3):603-612.
[7] 宋书伶,杨二龙,沙明宇.基于分子模拟的页岩油赋存状态影响因素研究[J].油气藏评价与开发,2023,13(1):31-38,51.
SONG Shuling,YANG Erlong,SHA Mingyu.Influencing factors of occurrence state of shale oil based on molecular simulation[J].Reservoir Evaluation and Development,2023,13(1):31-38,51.
[8] BURROWS L C,HAERI F,CVETIC P,et al.A literature review of CO2,natural gas,and waterbased fluids for enhanced oil recovery in unconventional reservoirs[J].Energy & Fuels,2020,89(10):278-279.
[9] OZOWE W,ZHENG S,SHARMA M.Selection of hydrocarbon gas for huff-n-puff IOR in shale oil reservoirs[J].Journal of Petroleum Science and Engineering,2020,89(10):98-99.
[10] TIAN Feng,LI Tiantai,HUANG Xing,et al.Adsorption behavior of CH4,C2H6 and CO2 on moisture equilibrated shale[J].Energy & Fuels,2020,57(7):647-652.
[11] 师调调,杜燕,党海龙,等.志丹油区长7页岩油储层CO2吞吐室内实验[J].特种油气藏,2023,30(11):128-134.
SHI Tiaotiao,DU Yan,DANG Hailong,et al.Indoor Experiment on CO2 Huff-n-puff in Chang 7 Shale Oil Reservoir in Zhidan Oil Region[J].Special Oil & Gas Reservoirs,2023,30(11):128-134.
[12] 曹长霄,宋兆杰,师耀利,等.吉木萨尔页岩油二氧化碳吞吐提高采收率技术研究[J].特种油气藏,2023,30(3):106-114.
CAO Changxiao,SONG Zhaojie,SHI Yaoli,et al.Study on CO2 huff-n-puff enhanced recovery technology for Jimsar shale oil[J].Special Oil & Gas Reservoirs,2023,30(3):106-114.
[13] 闫健,佀彬凡,孙晓东,等.页岩油储层超临界CO2吞吐用气溶性表面活性剂性能评价[J].断块油气田,2023,30(4):566-571.
YAN Jian,SI Binfan,SUN Xiaodong,et al.Performance evaluation of gas soluble surfactants for supercritical CO2 huff and puff in shale oil reservoirs[J].Fault-Block Oil & Gas Field,2023,30(4):566-571.
[14] 李蕾,郝永卯,王程伟,等.页岩油藏单相流体低速渗流特征[J].特种油气藏,2021,28(6):70-75.
LI Lei,HAO Yongmao,WANG Chengwei,et al.Low-velocity seepage characteristics of single-phase fluid in shale reservoir[J].Special Oil & Gas Reservoirs,2021,28(6):70-75.
[15] LASHGARI H R,SUN A,ZHANG T,et al.Evaluation of carbon dioxide storage and miscible gas EOR in shale oil reservoirs[J].Fuel,2018,241:1223-1235.
