Browsing by Subject "Compositional flow"
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Item Coupled flow and geomechanics modeling for fractured poroelastic reservoirs(2014-12) Singh, Gurpreet, 1984-; Wheeler, Mary F. (Mary Fanett)Tight gas and shale oil play an important role in energy security and in meeting an increasing energy demand. Hydraulic fracturing is a widely used technology for recovering these resources. The design and evaluation of hydraulic fracture operation is critical for efficient production from tight gas and shale plays. The efficiency of fracturing jobs depends on the interaction between hydraulic (induced) and naturally occurring discrete fractures. In this work, a coupled reservoir-fracture flow model is described which accounts for varying reservoir geometries and complexities including non-planar fractures. Different flow models such as Darcy flow and Reynold's lubrication equation for fractures and reservoir, respectively are utilized to capture flow physics accurately. Furthermore, the geomechanics effects have been included by considering a multiphase Biot's model. An accurate modeling of solid deformations necessitates a better estimation of fluid pressure inside the fracture. The fractures and reservoir are modeled explicitly allowing accurate representation of contrasting physical descriptions associated with each of the two. The approach presented here is in contrast with existing averaging approaches such as dual and discrete-dual porosity models where the effects of fractures are averaged out. A fracture connected to an injection well shows significant width variations as compared to natural fractures where these changes are negligible. The capillary pressure contrast between the fracture and the reservoir is accounted for by utilizing different capillary pressure curves for the two features. Additionally, a quantitative assessment of hydraulic fracturing jobs relies upon accurate predictions of fracture growth during slick water injection for single and multistage fracturing scenarios. It is also important to consistently model the underlying physical processes from hydraulic fracturing to long-term production. A recently introduced thermodynamically consistent phase-field approach for pressurized fractures in porous medium is utilized which captures several characteristic features of crack propagation such as joining, branching and non-planar propagation in heterogeneous porous media. The phase-field approach captures both the fracture-width evolution and the fracture-length propagation. In this work, the phase-field fracture propagation model is briefly discussed followed by a technique for coupling this to a fractured poroelastic reservoir simulator. We also present a general compositional formulation using multipoint flux mixed finite element (MFMFE) method on general hexahedral grids with a future prospect of treating energized fractures. The mixed finite element framework allows for local mass conservation, accurate flux approximation and a more general treatment of boundary conditions. The multipoint flux inherent in MFMFE scheme allows the usage of a full permeability tensor. An accurate treatment of diffusive/dispersive fluxes owing to additional velocity degrees of freedom is also presented. The applications areas of interest include gas flooding, CO₂ sequestration, contaminant removal and groundwater remediation.Item Interplay of multicomponent phase behavior and flow in steam-solvent coinjection for heavy-oil and bitumen recovery(2021-05-05) Sheng, Kai, Ph. D.; Okuno, Ryosuke, 1974-; Lake, Larry; Pyrcz, Michael; Sepehrnoori, Kamy; Li, HuazhouSteam-assisted gravity drainage (SAGD) is a commercially successful technology for heavy oil and bitumen recovery. The energy efficiency of SAGD is important for the economic feasibility and environmental sustainability of oil recovery. Solvent-assisted SAGD (SA-SAGD) has been widely studied and pilot-tested as an alternative to improve the energy efficiency of SAGD. One of the practical factors that affect oil producers is the produced oil properties. Multiphase behavior and reservoir flow collectively affect produced oil properties. However, the compositional effect on properties of the produced oil in SAGD and SA-SAGD remains unknown. This research focuses on answering the question of how the oil properties are affected by steam injection and solvent-steam coinjection, by studying the interaction of multicomponent phase behavior and reservoir flow. The research question was answered by an experimental and numerical investigation into SA-SAGD using condensate, a multicomponent solvent to be used for a field pilot in Alberta. It contains components with a broad range of carbon numbers and complicates the compositional flow in SA-SAGD. Steam injection experiments were conducted for SAGD and SA-SAGD in a large lab-scale physical model, and the compositional effect was analyzed through both compositional analysis for the produced oil and history matching with numerical simulation. Then, the compositional flow was further investigated in field-scale 3-D numerical simulations with heterogeneity representative of Athabasca oil sands, Alberta, Canada. Experimental results confirmed for the first time that SAGD produced lighter oil than the original bitumen because of the distillation of light-end bitumen components. Experimental and simulation results showed that the injected solvents suppressed the distillation of light bitumen fractions and caused the produced oil in SA-SAGD to become heavier than that in SAGD. Condensate components flowed separately according to their volatilities, and showed different levels of in-situ utilization efficiency and recovery factors. Reservoir heterogeneity tended to suppress the compositional separation by enhancing the in-situ mixing of components. Additionally, the water imbibition outside of a steam chamber was found to be significant in the early stage of SAGD through the experiment and caused the production of oil by water imbibition, instead of by gravity. A water-soluble organic alkali, diethylamine (DEA), was therefore investigated for its potential to enhance bitumen flow through flow experiments.Item Parallel simulation of coupled flow and geomechanics in porous media(2014-12) Wang, Bin, 1984-; Wheeler, Mary F. (Mary Fanett)In this research we consider developing a reservoir simulator capable of simulating complex coupled poromechanical processes on massively parallel computers. A variety of problems arising from petroleum and environmental engineering inherently necessitate the understanding of interactions between fluid flow and solid mechanics. Examples in petroleum engineering include reservoir compaction, wellbore collapse, sand production, and hydraulic fracturing. In environmental engineering, surface subsidence, carbon sequestration, and waste disposal are also coupled poromechanical processes. These economically and environmentally important problems motivate the active pursuit of robust, efficient, and accurate simulation tools for coupled poromechanical problems. Three coupling approaches are currently employed in the reservoir simulation community to solve the poromechanics system, namely, the fully implicit coupling (FIM), the explicit coupling, and the iterative coupling. The choice of the coupling scheme significantly affects the efficiency of the simulator and the accuracy of the solution. We adopt the fixed-stress iterative coupling scheme to solve the coupled system due to its advantages over the other two. Unlike the explicit coupling, the fixed-stress split has been theoretically proven to converge to the FIM for linear poroelasticity model. In addition, it is more efficient and easier to implement than the FIM. Our computational results indicate that this approach is also valid for multiphase flow. We discretize the quasi-static linear elasticity model for geomechanics in space using the continuous Galerkin (CG) finite element method (FEM) on general hexahedral grids. Fluid flow models are discretized by locally mass conservative schemes, specifically, the mixed finite element method (MFE) for the equation of state compositional flow on Cartesian grids and the multipoint flux mixed finite element method (MFMFE) for the single phase and two-phase flows on general hexahedral grids. While both the MFE and the MFMFE generate cell-centered stencils for pressure, the MFMFE has advantages in handling full tensor permeabilities and general geometry and boundary conditions. The MFMFE also obtains accurate fluxes at cell interfaces. These characteristics enable the simulation of more practical problems. For many reservoir simulation applications, for instance, the carbon sequestration simulation, we need to account for thermal effects on the compositional flow phase behavior and the solid structure stress evolution. We explicitly couple the poromechanics equations to a simplified energy conservation equation. A time-split scheme is used to solve heat convection and conduction successively. For the convection equation, a higher order Godunov method is employed to capture the sharp temperature front; for the conduction equation, the MFE is utilized. Simulations of coupled poromechanical or thermoporomechanical processes in field scales with high resolution usually require parallel computing capabilities. The flow models, the geomechanics model, and the thermodynamics model are modularized in the Integrated Parallel Accurate Reservoir Simulator (IPARS) which has been developed at the Center for Subsurface Modeling at the University of Texas at Austin. The IPARS framework handles structured (logically rectangular) grids and was originally designed for element-based data communication, such as the pressure data in the flow models. To parallelize the node-based geomechanics model, we enhance the capabilities of the IPARS framework for node-based data communication. Because the geomechanics linear system is more costly to solve than those of flow and thermodynamics models, the performance of linear solvers for the geomechanics model largely dictates the speed and scalability of the coupled simulator. We use the generalized minimal residual (GMRES) solver with the BoomerAMG preconditioner from the hypre library and the geometric multigrid (GMG) solver from the UG4 software toolbox to solve the geomechanics linear system. Additionally, the multilevel k-way mesh partitioning algorithm from METIS is used to generate high quality mesh partitioning to improve solver performance. Numerical examples of coupled poromechanics and thermoporomechanics simulations are presented to show the capabilities of the coupled simulator in solving practical problems accurately and efficiently. These examples include a real carbon sequestration field case with stress-dependent permeability, a synthetic thermoporoelastic reservoir simulation, poroelasticity simulations on highly distorted hexahedral grids, and parallel scalability tests on a massively parallel computer.