Research progress of thickener for supercritical carbon dioxide fracturing fluid

Abstract

Compared to traditional water-based fracturing fluids, which often result in reservoir fracturing damages, water consumption, and incomplete flowback, supercritical carbon dioxide (scCO₂) fracturing technology has gained attention from scholars as a promising anhydrous fracturing technique. This is primarily due to its unique properties such as being waterless, causing no reservoir damages, providing an excellent energy-enhancing effect, and enabling thorough backflow. In addition to improving the recovery efficiency through CO₂ injection during fracturing, scCO₂ fracturing technology also enables CO₂ geological storage. However, the low viscosity of pure CO₂ as a fracturing fluid significantly limits its productivity enhancement effect. Therefore, the identification of a suitable thickener is necessary to increase the viscosity of supercritical CO₂ fracturing fluids, consequently enhancing their reservoir reconstruction efficiency. This paper explores and discusses four types of supercritical CO₂ thickeners, namely siloxane polymers, hydrocarbon and oxygenated hydrocarbon polymers, surfactants, and fluoropolymers, through comprehensive research conducted domestically and internationally. The solubility, thickening ability, experimental conditions, and challenges associated with scCO₂ thickeners are analyzed and evaluated. Finally, the characteristics of each type of thickener are summarized, and future research directions are proposed.

Keywords

Supercritical CO₂ / EOR and fracturing / CO₂ thickener / Polymer / Chemical classification

CRediT authorship contribution statement

Wanfen Pu: Supervision, Methodology, Investigation, Validation. Jintao Li: Writing-review & editing, Writing-original draft, Investigation. Daijun Du: Supervision, Methodology, Investigation, Funding acquisition. Jinzhou Zhao: Supervision, Investigation. Tong Wu: Supervision, Software. Ying Xiong: Supervision. Pengfei Chen: Supervision. Rui Jiang: Supervision.

Declaration of competing interest

No conflict of interest exits in the submission of this manuscript, and all authors for publication approve manuscript. I would like to declare on behalf of my co-authors that the work described was original research that has not been published previously, and not under consideration for publication elsewhere, in whole or in part. All the authors listed have approved the manuscript that is enclosed.

Acknowledgements

This work is supported by the National Natural Science Foundation of China (52304043). The authors gratefully acknowledge the support of the State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University. The authors also thank the anonymous reviewers for their valuable comments.

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