| Title | The Implementation and Numerical Analysis of Fully-Coupled Non-Isothermal Fluid Flow Through a Deformable Porous Medium |
|---|---|
| Authors | Justin Pogacnik, Peter Leary, Peter Malin |
| Year | 2011 |
| Conference | New Zealand Geothermal Workshop |
| Keywords | fully coupled finite element model, deformable porous media, geothermal systems, heat and mass transfer, power-law scaling |
| Abstract | This work seeks to simulate subsurface fluid flow and heat transport within a deformable porous medium. Previous work indicates that it is imperative to consider the spatial fluctuations in well-log and well-core properties in numerical simulations involving non-deforming porous solids. The consideration of these property fluctuations naturally gives rise to preferential pathways of fluid flow and heat transport. Allowing for solid deformations offers a logical step forward to allow for stress-controlled fluctuations in well-log properties. A sophisticated numerical model will be able to capture the growth and collapse of underground voids and fractures due to fluctuations in fluid pressure, faulting, and temperature. The principal contribution of this work is this is the first time that full simulations have been performed of underground geothermal flows in a deformable porous medium that include realistic spatial fluctuations in well-log properties. To this end, the linear momentum, mass balance, and enthalpy balance equations have been coupled in a combined finite element and finite difference analysis. This analysis is limited to a single-phase fluid and linear elasticity, however, the method is robust enough to include multi-phase fluid flows and nonlinear bulk constitutive relations. The governing differential equations, discretized set of equations, solution technique, and verification tests will be presented. Preliminary results will be presented that indicate that this technique is capable of simulating the propagation of underground fracture networks. Future work includes the extension to three-dimensional analysis and the plan to implement a viscoplastic bulk constitutive model to account for solid material yield and thermal softening. After the introduction of multi-phase flows, chemical coupling of the differential equations may also be implemented to account for chemically-induced degradations in the solid material. |