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Hydraulic Crack Propagation in Heterogeneous Reservoir Based on Extended Multi-Scale Finite Element Method

Hajiabadi, Mohammad Reza | 2019

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 52207 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Khoei, Amir Reza
  7. Abstract:
  8. Many natural and engineering materials have a heterogeneous structure at a certain level of observation. These materials are often referred to as composite materials or multi-phase materials or heterogeneous materials. It has been widely recognized that many macroscopic phenomena originate from the mechanics of the microstructural constituents, such as inclusions, cracks, voids, etc. The size, shape, spatial distribution, volume fraction and properties of the microstructural constituents have a significant impact on the behavior of the material observed at the macroscale. The nature of hydrocarbon reservoirs as multi-phase porous media are known for heterogeneous media at various multiple scales. In this paper, a multiscale finite element framework is developed based on an extension of the Hill-Mandel theory for deformable saturated porous media in order to take into account of the effect of microdynamic terms. In the multiscale technique, the behavior of a material point is obtained from an interactive process between 2 scales, named as the “microscale” and “macroscale.” The homogenized properties of each computational point are derived from the solution of a boundary value problem upon a given microstructure that identifies the representative volume element. In the presented framework, a fully couple hydromechanical boundary value problem is solved at microscale in a transient regime. The effects of various issues, including microdynamic effects, boundary conditions, size effects, microstructural pattern, and integral domain constraints for the microscale boundary value problem, are numerically investigated by a consolidation of one dimensional soil column problem. It is shown that the multi-scale homogenization can solve the idealized sugar-cube model, which is generally employed in fractured porous media on the basis of dual porosity models. With introducing equivalent properties between the multiscale and dual porosity models, several comparisons are performed between the results of these two analysis and those obtained from direct numerical simulations through two problems, including a consolidation problem and five spot water flood in a fractured reservoir. Moreover, a combined multiscale – dual porosity technique is introduced to benefit form the advantages of both techniques in a single model. In addition, traction-seperation law in homogenized isotropic materials for the opening mode of cohesive crack propagation is derived base on mechanical damage at microscale
  9. Keywords:
  10. Multi-Scale Analysis ; Saturated Porous Medium ; Heterogeneous Reservoirs ; Dual Porosity ; Hydraulic Crack Propagation ; Extended Finite Element Method

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