Open Access

ARTICLE

Experimental Investigation of Fracture Propagation Induced by Supercritical CO₂ in Deep Shale Reservoirs

Taizhi Shen¹, Gang Chen¹, Jiang Bai¹, Dan Zhang^2,*

1 Wuqi Oil Production Plant, Shaanxi Yanchang Petroleum, Xi’an, 716000, China
2 State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, 610500, China

* Corresponding Author: Dan Zhang. Email:

Fluid Dynamics & Materials Processing 2025, 21(8), 1917-1934. https://doi.org/10.32604/fdmp.2025.067114

Received 25 April 2025; Accepted 17 July 2025; Issue published 12 September 2025

Abstract

Deep shale reservoirs are often associated with extreme geological conditions, including high temperatures, substantial horizontal stress differences, elevated closure stresses, and high breakdown pressures. These factors pose significant challenges to conventional hydraulic fracturing with water-based fluids, which may induce formation damage and fail to generate complex fracture networks. Supercritical carbon dioxide (SC-CO₂), with its low viscosity, high diffusivity, low surface tension, and minimal water sensitivity, has attracted growing attention as an alternative fracturing fluid for deep shale stimulation. This study presents a series of true triaxial large-scale physical experiments using shale samples from the Longmaxi Formation in the southern Sichuan Basin to investigate fracture initiation and propagation behavior under different fracturing fluids. The results show that, under identical experimental conditions, SC-CO₂ fracturing results in a significantly lower breakdown pressure compared to slick water and promotes the formation of more complex fracture geometries. These advantages are attributed to both the favorable flow characteristics of SC-CO₂ and its potential chemical interactions with shale minerals. The findings not only confirm the effectiveness of SC-CO₂ as a fracturing fluid in deep shale environments but also provide new insights into its fracture propagation mechanisms.

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Keywords

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