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The Influence of Acid on the Rock Mechanical Characteristics of Deep Shale in the Wujiaping Formation

Hao Zhang1, Yan Zhang1,*, Wei Liu2, Ximin Zhang3, Xiang Liu2

1 School of Petroleum Engineering, Yangtze University, Wuhan, 430100, China
2 Petroleum Engineering Technology Research Institute, Jianghan Oilfield Branch of Sinopec, Wuhan, 430035, China
3 Drilling Technology Research Institute, Sinopec Shengli Oilfield Service Corporation, Deyang, 618000, China

* Corresponding Author: Yan Zhang. Email: email

Energy Engineering 2024, 121(1), 27-42. https://doi.org/10.32604/ee.2023.041410

Abstract

The microscopic characteristics and mechanical properties of rocks change after the action of acid on deep shale, which affects the fracturing effect. Accordingly, we designed and conducted indoor experiments related to the changes in macro and microscopic characteristics after the interaction of acid with the shale of Wujiaping Formation, based on which the characteristic law of fracture volume modification after acid fracturing was studied using numerical simulation. The results demonstrate that the pores and fractures are enlarged and the structure is significantly loosened after the acid immersion. And a 15% concentration of hydrochloric acid can effectively dissolve shale. Furthermore, the degree of acid-etching reaction is highly variable because of the different carbonate content, which reveals the strong inhomogeneity of the shale system in the Wujiaping Group reservoir section. After the acid interacted with the shale rock samples, the triaxial compressive strength, elastic modulus, and Poisson’s ratio of shale decreased. Moreover, the evaluation of the effect after acid fracturing simulated by fracturing software revealed that the smaller the value of elastic modulus in shale-based reservoirs, the more favorable the fracture volume modification. This discovery not only provides a theoretical basis for the expansion and extension patterns of acid-fracturing in carbonaceous shale formations but also offers research methods and theoretical insights for the fundamental exploration of other deep-seated oil and gas resources.

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Cite This Article

Zhang, H., Zhang, Y., Liu, W., Zhang, X., Liu, X. (2024). The Influence of Acid on the Rock Mechanical Characteristics of Deep Shale in the Wujiaping Formation. Energy Engineering, 121(1), 27–42.



cc This work is licensed under a Creative Commons Attribution 4.0 International License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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