Study on the Plugging Mechanism of Carbon Dioxide Oil Drive in Shale

Abstract

The CO₂ enhanced oil recovery(EOR) technology is widely utilized in the development of shale oil reservoirs. However, reservoir plugging issues often occur during the CO₂ injection process, leading to reduced onsite development efficiency. Currently, the mechanism behind reservoir plugging is still unclear. Therefore, this research selects Jimsar crude oil from Xinjiang to conduct CO₂ displacement experiments on shale cores and analysis of crude oil components. A comparative analysis is conducted with previous studies to explore the plugging mechanism. The research results demonstrate that core plugging occurs when the displacement pressure exceeds 25 MPa, resulting in a significant decrease in core permeability. Under a displacement pressure of 40 MPa, the additional resistance accounts for as much as 72% of the total resistance, with high asphalt content and the extractive effect of CO₂ on crude oil components being important factors leading to core plugging. Therefore, in the field development process, the CO₂ enhanced oil recovery technology should be applied in a rational and tailored manner according to the properties of the field’s crude oil.