Fluid-driven cracking behavior of coal with prefabricated plane: A particle-based hydro-mechanical coupled numerical investigation. (April 2023)

• Record Type: Journal Article
• Authors: Lu, Yiyu; Huang, Shan; Ge, Zhaolong; Zhou, Zhe; Song, Zhengyang
• Is Part Of: Theoretical and applied fracture mechanics. Volume 124(2023)
• Publication Date: 2023-04
• Subjects: Coal seam -- Hydraulic fracturing -- Discrete element method -- Coupled hydro-mechanical model; Fracture mechanics -- Periodicals; 620.1126
• DOI: 10.1016/j.tafmec.2023.103825
• Languages: English
• ISSNs: 0167-8442

Abstract

Highlights: DEM based fluid-driven fracture propagation behavior in coal rock is simulated using PFC2D. Intersection mode of HF and NP in coal subjected to distinct geo stress and approaching angle during hydraulic fracturing is analyzed and compared with other rock masses. Low approaching angles of natural plane in coal can facilitate the generation of more complex hydro-fractures. High injection rate and less in-situ stress difference is more conducive to branch and random distribution of hydraulic fractures near borehole in coal rock. Abstract: To better understand the propagation characterizations of hydraulic fracture (HF) in coal with natural planes (NP), a fully coupled fluid flow-DEM method is employed, and a series of numerical simulations are carried out. The impact of the NP approaching angle (the angle between NP and the horizontal direction), in-situ geo-stress, the fluid flow injection rate on the fracture propagation behavior and breakdown pressure is analyzed. It is concluded that three interaction modes can be simulated, and the existence of NPs with low strength and approaching angles can facilitate the development of more complex fracture networks in coal rock. Intersection mode of HF and NP in coal subjected to different approaching angle is more sensitive comparing to other rock masses. Distinct injection rates, in-situ stress difference of NP also play a key role in determining HF morphology and its interaction mode with NP. The findings in this study may provide a numerical reference for optimizing the design of hydraulic fracturing in coal.