Evaluation of acid fracturing in carbonatite geothermal reservoirs based on a coupled thermo-hydro-mechanical-chemical model considering discrete fracture networks

IF 3.7 2区工程技术 Q3 ENERGY & FUELS

Geomechanics for Energy and the Environment Pub Date : 2025-06-18 DOI:10.1016/j.gete.2025.100704

Jia Liu , Wenqi Zhang , Yi Xue , Huimin Wang , Shi-Tong Li , Yun Zhang , Weihua Li

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引用次数: 0

Abstract

In the development of carbonate geothermal reservoirs, the implementation of acid fracturing technology is common and essential, effectively enhancing reservoir permeability. It encompasses a sequence of intricate phenomena including solute migration, acid-rock reaction, heat transfer, and deformation. Herein, a comprehensive thermo-hydro-mechanical-chemical (THMC) coupling model considering field-scale discrete fracture networks (DFNs) is established for the process. With the thin elastic layer and fracture element assumptions, the corrosion and deformation of fractures are considered simultaneously. Additionally, the model accounts for the corrosion effects of both bedrock and fracture surfaces, and tracks the evolution of fracture aperture and matrix porosity. Using the proposed model, this study investigates acid fracturing in varying reservoir and operational conditions. It is found that the connectivity of DFN can influence the seepage path of acid fluid, therefore affecting acid concentration transport, which has a significant impact on the reconstruction of reservoir acidification. The acidification effectiveness nonlinearly positively correlates to the rate and concentration of acid injection, while the change of chemical aperture is negatively correlated to the initial fracture aperture. Reservoir temperature has a limited influence on acidification outcomes. The scientific insights provided here are valuable in steering the optimization of acid fracturing in carbonatite reservoirs.

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考虑离散裂缝网络的热-水-力-化学耦合模型碳酸盐岩地热储层酸压评价

在碳酸盐岩地热储层开发中，实施酸压技术是普遍和必不可少的，能有效提高储层渗透率。它包含了一系列复杂的现象，包括溶质迁移、酸岩反应、传热和变形。在此基础上，建立了考虑现场尺度离散裂缝网络（DFNs）的热-水-机械-化学（THMC）综合耦合模型。采用薄弹性层和断裂单元假设，同时考虑了断裂的腐蚀和变形。此外，该模型考虑了基岩和裂缝表面的腐蚀效应，并跟踪裂缝孔径和基质孔隙度的演变。利用所提出的模型，研究了不同储层和作业条件下的酸压裂。研究发现，DFN的连通性会影响酸性流体的渗流路径，从而影响酸浓度的输运，对储层酸化改造有重要影响。酸化效果与注酸速率和注酸浓度呈非线性正相关，而化学孔径的变化与初始裂缝孔径呈负相关。储层温度对酸化效果的影响有限。本文提供的科学见解对于指导碳酸盐岩储层酸压裂的优化具有重要价值。

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来源期刊

Geomechanics for Energy and the Environment Earth and Planetary Sciences-Geotechnical Engineering and Engineering Geology

CiteScore

5.90

自引率

11.80%

发文量

期刊介绍： The aim of the Journal is to publish research results of the highest quality and of lasting importance on the subject of geomechanics, with the focus on applications to geological energy production and storage, and the interaction of soils and rocks with the natural and engineered environment. Special attention is given to concepts and developments of new energy geotechnologies that comprise intrinsic mechanisms protecting the environment against a potential engineering induced damage, hence warranting sustainable usage of energy resources. The scope of the journal is broad, including fundamental concepts in geomechanics and mechanics of porous media, the experiments and analysis of novel phenomena and applications. Of special interest are issues resulting from coupling of particular physics, chemistry and biology of external forcings, as well as of pore fluid/gas and minerals to the solid mechanics of the medium skeleton and pore fluid mechanics. The multi-scale and inter-scale interactions between the phenomena and the behavior representations are also of particular interest. Contributions to general theoretical approach to these issues, but of potential reference to geomechanics in its context of energy and the environment are also most welcome.