Numerical analysis of different fracturing mechanisms between supercritical CO2 and water-based fracturing fluids

Research output: Contribution to journalArticle

Abstract

Hydraulic fracturing using water-based fluid consumes a large amount of freshwater resources and pollutes a reservoir by substantially decreasing its matrix permeability. To address the problems caused by water-based fracturing fluids, the possibility of using SC-CO2 as a fracturing fluid was studied for its special properties (such as low viscosity, high density, and miscibility with hydrocarbons). Previous experimental studies have indicated that SC-CO2 is superior to water-based fracturing fluid in inducing complex fractures at the laboratory scale, while the mechanism of complex fractures induced by SC-CO2 remains unclear. This study develops a new numerical model to simulate the different performances of SC-CO2 fracturing and water-based fluid fracturing to determine the mechanisms of complex fractures. The numerical model couples an unsteady flow model based on the pore-scale network method and a solid model using the finite element method with cohesive zone elements. The unsteady flow model reproduces a two-phase flow considering viscous and capillary forces at the pore scale. Our simulation results show that both viscous and capillary forces contribute to the different fracturing performances between SC-CO2 and water-based fluid. The capillary force should be considered in the flow model when simulating fracturing in low matrix permeability rock.

Original languageEnglish
Article number104385
JournalInternational Journal of Rock Mechanics and Mining Sciences
Volume132
DOIs
Publication statusPublished - 2020 Aug

Keywords

  • Complex fracture
  • Rough fracture surface
  • SC-CO fracturing
  • Shale rock

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology

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