Microscopic Mechanism of CO 2 Displacement Oil in Different Pore Throat Radius Segments of Tight Sandstone Reservoirs

作者：Yu‐Ting Cheng, Yiqian Qu, Xin Cheng, Jun Ni, Zhenzhen Zhou, Shuqi Lan, Zhengqi Yang, Liancheng Wei, Hanning Wu, Wei Sun · 发表于：ACS Omega · 年份：2024 · DOI：10.1021/acsomega.4c05324 · 被引用次数：14 · 研究领域：Enhanced Oil Recovery Techniques、Hydrocarbon exploration and reservoir analysis、CO2 Sequestration and Geologic Interactions

High Resolution Image Download MS PowerPoint Slide The micropore structure of tight sandstone affects the efficiency of CO 2 displacement of crude oil. As the pressure changes, the oil displacement efficiency ( E d ) in segments with different pore radii changes, and the asphaltene precipitation in the pores causes alterations in the pore structure and wettability, which constrain E d . Ten samples of tight sandstone from the Yanchang Formation in the Ordos Basin were selected for this study. A variety of methods, including X-ray diffraction (XRD), casting thin sections (CTS), scanning electron microscopy (SEM), high-pressure mercury intrusion (HPMI), CT scanning, and nuclear magnetic resonance (NMR) combined with CO 2 displacement, were used to study the efficiency of crude oil utilization and the amount of asphaltene deposited at different pore-throat radii, and then the impacts of pressure, pore structure, and wettability changes on E d were discussed. The findings indicate that samples have three types: macropore-fine throats (MF), medium pore-tiny throats (MT), and small pore-microthroats (SM). The MT exhibits a favorable configuration. The pore-throat radius of each sample can be divided into two segments, namely, large pore segments (P L ) and small pore segments (P S ), and the P L has a significant E d . The E d of the MF-type P S is constrained by pressure. The E d of P L is significantly affected by the pressure sensitivity for the MT, while the E d of P L for the ...