日用化学工业（中英文）2025，Vol.55Issue(7)：853-860,8.DOI:10.3969/j.issn.2097-2806.2025.07.005
CO2长期注入对超低渗透储层及赋存流体性质影响实验研究
Experimental study on the impacts of long-term CO2 injection on ultra-low permeability reservoirs and fluid properties
摘要
Abstract
The Yanchang oilfield is an ultra-low permeability reservoir with low matrix permeability,high proportion of nanoscaled pore throats,complex pore-throat structures,high salinity of formation water,and high mass concentration of Ca2+.The interactions among CO2-formation water-rock and CO2-crude oil exert more complex impacts on reservoir properties and fluid characteristics in such reservoirs.Targeted studies were conducted at three CO2 flooding areas(Huaziping,Qiaojiawa,and Baibao)to investigate these interaction mechanisms.The results showed that long-term CO2 injection significantly affected the reservoir properties and fluid characteristics in ultra-low permeability reservoirs.Due to the water-rock interaction,the core porosity,permeability,and contact angle were all decreased,with the magnitude of decrease initially increasing then decreasing as injection pressure was raised.Meanwhile,with the increase of pressure,the mass concentrations of HCO3-and Ca2+increased and then reached a plateau.Under actual injection pressures,the overall core blockage rates in the three tested areas were 7.71%,8.65%,and 13.88%,respectively,with more severe plugging observed for smaller pores(corresponding blockage rates were 21.36%,26.66%and 32.81%).The porosity and permeability under the influence of CO2-crude oil interaction showed similar trends to those under water-rock interaction.Increasing injection pressure enhanced the C3-C14 and C15-C29 components but reduced the C30+fractions and asphaltene content in produced oil,so the viscosity of crude oil correspondingly decreased rapidly.After the minimum miscible pressure was reached,the composition and the viscosity of crude oil became unchanged.Under actual injection pressures,the core blockage rates were 15.81%,18.85%and 20.69%,respectively,with blockage predominantly in medium and small pores.Under miscible conditions,the core blockage rate in Baibao area in these pores was 20.84%and 11.92%higher than those in Huaziping and Qiaojiawa,respectively,reflecting stronger CO2-oil interactions during miscible flooding.关键词
超低渗透油藏/CO2驱/水岩反应/沥青质沉积/延长油田Key words
ultra-low permeability reservoir/CO2 flooding/water-rock interaction/asphaltene deposition/Yanchang oilfield分类
化学化工引用本文复制引用
杨红,杨康,李鹏宇,刘瑛,李超跃..CO2长期注入对超低渗透储层及赋存流体性质影响实验研究[J].日用化学工业（中英文）,2025,55(7):853-860,8.基金项目
国家重点研发计划项目(2022YFE0206700) （2022YFE0206700）
