Loading...

Numerical Simulation of Hydraulic Fracturing in Porous Media Considering Two Phase Flow and Thermal Effects Using Mesh-less XEFG Method

Iranmanesh, Mohammad Ali | 2020

660 Viewed
  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 53161 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Pak, Ali
  7. Abstract:
  8. In this study, a fully coupled three-dimensional numerical analysis of two-phase fluid flow and heat transfer through deformable porous media is presented in the context of extended element free Galerkin method. By coupling momentum balance equation for the whole mixture, continuity equations of wetting and non-wetting fluid phases and energy balance equation, the developed numerical algorithm is capable of simulating a wide range of engineering problems such as CO2 sequestration, nuclear waste disposal in deep underground strata, hydraulic fracturing in oil and gas reservoirs and so on.By taking the advantages of partition of unity property of MLS shape functions, weak and strong discontinuities are introduced in field variables using the enrichment strategy. To achieve this goal, the Heaviside function is used for the simulation of strong discontinuities such as cracks and impermeable internal boundaries and the Ridge function is employed for the simulation of weak discontinuities like the boundary between two different soils.Since for quasi-brittle materials such as soils and concrete, the size of nonlinear zone at the crack front due to plasticity or micro-cracking is not negligible in comparison with other dimensions of the crack geometry, the cohesive crack model is used in this study to simulate the process of initiation and propagation of fractures in multiphase porous media. Also, the normal contact between the crack edges is considered by using the penalty method.The complicated process of hydraulic fracturing with thermal effects is simulated by considering multiple ingredients including (I) the fluid flow within the fracture, (II) the fluid flow through the host medium, (III) the fluid leak-off from the fracture medium into the surrounding porous rock, (IV) the deformation of the surrounding medium due to the hydraulic loading and (V) the crack propagation.
    To create the discrete equation system, the Galerkin technique is applied, and the essential boundary conditions are imposed via penalty method. Then, the resultant constrained integral equations are discretized in space using EFG shape functions. For temporal discretization, a fully implicit scheme is employed. The final set of algebraic equations that forms a non-linear equation system is solved using the iterative Newton-Raphson procedure.The model performance is evaluated by comparing the numerical results with analytical solutions, field measurements and numerical solutions that are reported by other researchers. It is demonstrated that the proposed numerical approach and the developed computer program are capable of simulating various THM problems in continuous and discontinuous porous media such as the process of hydraulic fracturing problem considering the thermal effects.
  9. Keywords:
  10. Hydraulic Fracturing ; Cohesive Crack Model ; Numerical Modeling ; Meshless Method ; Fully Coupled Analysis ; Thermal Hydraulic Analysis Code (THAC) ; Element Free Galerkin Method (EFGM) ; Extrinsic Enrichment ; Extended Element Free Galerkin (XEFG)Method ; Thermal-Hydraulic-Mechanical Analysis (THMA)

 Digital Object List

 Bookmark

No TOC