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标题：EXPERIMENTAL STUDY ON OPTIMIZATION OFSUPERCRITICAL CO2 VISCOSITY IN UNCONVENTIONALSHALE RESERVOIR FRACTURING
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作者：Jianping Lan ; Xing Huang ; Xiaoming Chi 等
期刊名称：Fresenius Environmental Bulletin
印刷版ISSN：1018-4619
出版年度：2020
卷号：29
期号：11
页码：9763-9769
语种：English
出版社：PSP Publishing
摘要：Unconventional shale reservoirs have the characteristics of low permeability,low porosity and high clay content.The elastic production process has a low production capacity.Conventional hydraulic fracturing could cause severe water absorption and clay expansion,resulting in poor fracturing efficiency.Supercritical CO2 fracturing fluid can effectively avoid the phenomenon of clay swelling and water absorption,and the fracture distribution after fracturing is complex.In this paper,six sets of supercritical CO2 fracturing shale experimental studies were conducted.The low sand-carrying capacity caused by the low density of supercritical CO2 were improved.The rupture pressure and initiation time of supercritical CO2 fracturing fluid with different viscosity were recorded,and the final fracturing effect was evaluated by the synergistic coefficient.The experimental results show that increasing the viscosity of supercritical CO2 fracturing fluid will increase the rupture pressure and reduce the initiation pressure time.The fracture shape is maintained well after fracturing.The optimal efficiency coefficient is 233.The research in this paper shows that increasing the viscosity of supercritical CO2 fracturing fluid can effectively reduce the initiation pressure time,and can obtain a better fracturing development effect in unconventional shale reservoirs.
关键词：Shale reservoir;supercritical CO2 fracturing;viscosity;synergistic coefficient