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Prediction of Hydraulic Fracturing Technology in Naturally Fractured Rocks, by Considering Immiscible Two-phase Flow

Ranjbaran, Mohammad | 2017

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 49925 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Taghikhani, Vahid; Ayatollahi, Shahab; Shad, Saeed; Ranjbaran, Abdolrasul
  7. Abstract:
  8. To have a deeper understanding of Hydraulic fracturing operation, in this study four important parts in this field was developed and simulated. In the first part, continuity and momentum equations for a single phase flow in a propagating penny-shaped fracture inside an impermeable matrix was revisited based on a fixed coordinate system. Its correctness was validated against experimental data and its features were compared with the well-known lubrication theory in analytical form. The new derived continuity equation caused the fracture tip to have a positive and finite pressure while, the conventional model predicted negative infinity for that. In the second part, Finite Volume method was extended to fluid flow of a single phase naturally fractured matrix with a single producing hydraulic fracture inside. Its main feature was the independency of the mesh and the angle of deviation of any of the fractures inside. The correctness of the codes were verified by using COMSOL® Multiphysics 4.4. In addition, in this part, when the natural fractures were parallel to pressure gradient inside the matrix, fracture productivity increased. However, when they were perpendicular, fracture productivity decreased. Furthermore, the linear relation between fracture productivity and length was determined. In the third part, pore network modeling concept was used for calculation of Biot-Willis coefficient and framework shear modulus of an isotropic poroelastic system which resulted into a set of algebraic equations against porosity, pore volume fraction, and solid part properties. A set of data for seven carbonate formations from all around the world was gathered and used for investigating the effectiveness of the proposed poroelastic property models. Finally, in the fourth part, a deep analytical study was implemented on relative permeability curves for two-phase flow in a naturally or hydraulically rough fracture. In this section a new quantity, named degree of phase interference, was defined and its dependency to fracture roughness was calculated. This parameter as well as irreducible wet phase saturation are the key parameters which control the curvature and non-wet relative permeability end point, respectively
  9. Keywords:
  10. Finite Volume Method ; Hydraulic Fracturing ; Fractured Porous Media ; Carbonated Rock ; Poroelastic ; Hydraulic Fracture Propagation ; Immiscible Two-Phase Flow ; Rough Fracture

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