Fluid and heat flow in enhanced geothermal systems considering fracture geometrical and topological complexities: An extended embedded discrete fracture model

RENEWABLE ENERGY

卷:179

Article

Zheng, Shuai¹  Li, Sanbai²  Zhang, Dongxiao² 

[1] Peking Univ, Coll Engn, BIC ESAT, ERE & SKLTCS, Beijing 100871, Peoples R China

[2] Southern Univ Sci & Technol, Sch Environm Sci & Engn, Shenzhen 518055, Peoples R China

关键词: Non-planar fractures;    EDFM;    Enhanced geothermal systems (EGS);    Fracture modeling;    Fracture roughness;   

DOI  :  10.1016/j.renene.2021.06.127

来源: Elsevier

【 摘 要 】

Accurate and efficient simulation of fluid and heat flow in fractures has long been a topic of interest for fractured reservoirs, e.g., enhanced geothermal systems (EGS) and unconventional oil/gas formations. In this paper, we propose a flexible and effective modeling approach, the extended embedded discrete fracture model (XEDFM), to simulate fluid and heat flow in fractured reservoirs with 3-D non-planar fracture networks. Compared with the conventional embedded discrete fracture model (EDFM), the XEDFM possesses two major merits: (1) separation of fracture discretization and matrix gridding provides maximum flexibility in handling fractures with complex geometry/topology, regardless of the resolution of the matrix grid; and (2) the combination of connection-list strategy and the concept of non neighboring connection facilitates the construction of fluid-heat flux between the fracture and the matrix/fracture. With systematically validated XEDFM, the impacts of fracture roughness and heat extraction strategy on hydrothermal behaviors and heat mining efficiency are investigated. Another example introduces a workflow for design and modeling of 3-D non-planar fracture networks, with which the performance of horizontal and vertical wells in tapping heat energy from EGS are explored. This work presents a flexible and effective approach for modeling fluid/heat transfer accurately in 3-D non-planar fractures, and provides a set of framework and efficient algorithms for non-planar fractures design, discretization and simulation, establishing the foundation to build and simulate models with complicated fractures. (C) 2021 The Authors. Published by Elsevier Ltd.

【 授权许可】

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