地质科技通报2026，Vol.45Issue(2)：11-19,9.DOI:10.19509/j.cnki.dzkq.tb20240452
CO2驱替对致密砂岩孔隙结构的影响:以鄂尔多斯盆地三叠系延长组长7段为例
Effect of CO2 flooding on the pore structure of tight sandstones:A case study of Chang 7 Member of Triassic Yanchang Formation in Ordos Basin
摘要
Abstract
[Objective]CO2 flooding is a crucial technology for enhancing oil recovery efficiency in tight oil reservoirs.CO2 injection reacts with in situ minerals in the formation,leading to changes in the pore structure of the rock.However,tight sandstones undergo complex diagenesis with significant differences in cement distribution,and it is therefore necessary to clarify the mechanisms of microstructural changes in tight sandstones with different cement characteristics during the CO2 flooding process.[Methods]In this study,CO2 flooding simulation experiments,cast thin sections analysis,scanning electron microscopy(SEM),nuclear magnetic resonance,and X-ray diffraction were adopted to investigate the changes in mineral composition and pore structures of tight sandstones before and after CO2 flooding.[Results]The results showed that the cements in tight sandstones were complex and diverse,mainly composed of clay minerals and calcite,with significant distribution differences among different cement types.Cements affected the mineralogical structure and pore morphology of tight sandstones.After CO2 flooding,the average porosity increment of tight sandstones reached 0.55%,the average permeability increase rate was 21.59%,and the average relative sorting coefficient decreased by only 0.01,indicating that CO2 flooding increased the porosity and permeability of the reservoir,but had a weak impact on the heterogeneity of the pore structure.During CO2 flooding,feldspar and calcite were dissolved,resulting in the precipitation of quartz and clay minerals.In tight sandstone with high clay content,CO2 dissolution was dispersed,and the newly precipitated minerals and clay detached from framework grains blocked pores,leading to minor changes in petrophysical properties.In tight sandstones with high calcite content,carbonic acid dissolved large amounts of calcite,creating new storage spaces and flow paths,significantly improving the petrophysical properties of tight sandstones.Therefore,CO2 flooding has different effects on the pore structure of tight sandstones with varying cement characteristics.CO2 flooding results in a much more significant improvement in the physical properties of tight sandstones with high calcite content than those with high clay content.[Conclusion]These results can provide new insights for the development and evaluation of tight sandstone reservoirs.关键词
CO2 驱替/孔隙结构/致密砂岩/矿物成分/鄂尔多斯盆地Key words
CO2 flooding/pore structure/tight sandstone/mineral composition/Ordos Basin分类
天文与地球科学引用本文复制引用
吴小斌,强小龙,张晓燕,李刚,解强旺,王伟..CO2驱替对致密砂岩孔隙结构的影响:以鄂尔多斯盆地三叠系延长组长7段为例[J].地质科技通报,2026,45(2):11-19,9.基金项目
国家自然科学基金项目(42362023) （42362023）
陕西省教育厅青年创新团队项目(24JP217 （）
22RCYPJB0103) （）
榆林市青年科技新星项目(2024-KJZG-QNXX-007) （2024-KJZG-QNXX-007）
陕西省科技厅项目(2025JC-YBQN-456 （）
2025JC-YBMS-452) （）
中国科学院洁净能源创新研究院-榆林学院联合基金项目(YLU-DNL Fund 2022012) （YLU-DNL Fund 2022012）
