Simulation of the interactions between hydraulic and natural fractures using a fracture mechanics approach

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Abstract

HYDROCK method aims to store thermal energy in the rock mass using hydraulically propagated fracture planes. The hydraulic fractures can interact with the pre-existing natural fractures resulting in a complex fracture network, which can influence the storage performance. This study investigates the interactions between hydraulic and natural fractures using a fracture mechanics approach. The new functionality of the fracture mechanics modelling code FRACOD that enables crossing of hydraulically driven fracture by a pre-existing fracture is presented. A series of two-dimensional numerical models is prepared to simulate the interaction at different approach angles in granitic rock of low permeability. It is demonstrated that multiple interaction mechanisms can be simulated using the fracture mechanics approach. The numerical results are in agreement with the modified Renshaw and Pollard analytical criterion for fracture crossing. The results show that for large approach angles, the hydraulic fracture crosses the natural fracture, whereas for small approach angles, the hydraulic fracture activates the natural fracture and the wing-shaped tensile fractures are propagated from its tips. Thus, the presence of fractures with low dip angles can lead to the growth of more complex fracture network that could impair the thermal performance of the HYDROCK method.
Original languageEnglish
Pages (from-to)1138-1150
JournalJOURNAL OF ROCK MECHANICS AND GEOTECHNICAL ENGINEERING
Volume11
Issue number6
Early online date1 Aug 2019
DOIs
Publication statusPublished - 3 Dec 2019
MoE publication typeA1 Journal article-refereed

Keywords

  • Hydraulic fracturing
  • Fractured rock
  • FRACOD model
  • Artificially fractured hard rock aquifer
  • Granite
  • HYDROCK
  • Underground thermal energy storage

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  • Projects

    CSIRO

    Rinne, M., Janiszewski, M. & Siren, T.

    01/02/201731/12/2019

    Project: Other external funding: Other foreign funding

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