Relative Permeability Characteristics During Carbon Capture and Sequestration Process in Low-Permeable Reservoirs.

Mingxing Bai,Lu Liu,Chengli Li,Kaoping Song

doi:10.3390/ma13040990

Abstract

The injection of carbon dioxide (CO2) in low-permeable reservoirs can not only mitigate the greenhouse effect on the environment, but also enhance oil and gas recovery (EOR). For numerical simulation work of this process, relative permeability can help predict the capacity for the flow of CO2 throughout the life of the reservoir, and reflect the changes induced by the injected CO2. In this paper, the experimental methods and empirical correlations to determine relative permeability are reviewed and discussed. Specifically, for a low-permeable reservoir in China, a core displacement experiment is performed for both natural and artificial low-permeable cores to study the relative permeability characteristics. The results show that for immiscible CO2 flooding, when considering the threshold pressure and gas slippage, the relative permeability decreases to some extent, and the relative permeability of oil/water does not reduce as much as that of CO2. In miscible flooding, the curves have different shapes for cores with a different permeability. By comparing the relative permeability curves under immiscible and miscible CO2 flooding, it is found that the two-phase span of miscible flooding is wider, and the relative permeability at the gas endpoint becomes larger.

Highlights

The injection of carbon dioxide (CO2 ) in depleted oil and gas reservoirs, saline aquifers, or coal seams, is an important means of reducing air pollution and mitigating the greenhouse effect on the environment, and it has been extensively discussed in previous studies [1,2,3,4,5,6,7]
For developing countries such as China, it can serve as an important measure to enhance oil and gas recovery, especially in lowor ultralow-permeable reservoirs, since the oil in low-permeable reservoirs accounts for approximately
A variety of methods to measure relative permeability in porous media are basically categorized among them, horizontal wells play a vital role due to their large flow areas [12]

Summary

Introduction

The injection of carbon dioxide (CO2 ) in depleted oil and gas reservoirs, saline aquifers, or coal seams, is an important means of reducing air pollution and mitigating the greenhouse effect on the environment, and it has been extensively discussed in previous studies [1,2,3,4,5,6,7]. For developing countries such as China, it can serve as an important measure to enhance oil and gas recovery, especially in lowor ultralow-permeable reservoirs, since the oil in low-permeable reservoirs accounts for approximately. Water flooding in low-permeable reservoirs results in a very unsatisfactory recovery, due to serious heterogeneity, tight lithology, high filtration resistance, poor pressure transmissibility and water sensitive minerals, and so on. With this regard, CO2 flooding is superior to water flooding, because it can maintain the reservoir pressure, and improve the displacement efficiency [9,10,11]. In order to increase oil production and CO2 injection efficiency, a number of methods are used, and among them, horizontal

Methods

Discussion

Conclusion