A New Multi-scale Computational Model for Flow and Transport in Shale Gas Reservoirs
Event details
| Date | 17.09.2014 |
| Hour | 09:30 › 10:30 |
| Speaker | Prof. Marcio A. Murad, National Laboratory for Scientific Computing LNCC/MCTI, Brazil |
| Location |
GC D0 386
|
| Category | Conferences - Seminars |
The macroscopic behavior of gas flow and transport in multi-porosity shale gas reservoirs is rigorously derived within the framework of the reiterated homogenization procedure applied to the Thermodynamics of inhomogeneous gases in nanopores. At the finest nanoscale the Density Functional Theory is applied to construct general adsorption isotherms and local density profiles of pure methane which reflect both repulsive hard sphere effects and Lennard-Jones attractive intermolecular interactions between fluid-fluid supplemented by a fluid-solid exterior potential. Such local description reproduces the monolayer surface adsorption ruled by the Langmuir isotherm in the asymptotic regime of large pore size distributions. The nanoscopic model is upscaled to the microscale where kerogen particles and nanopores are viewed as overlaying continua forming the organic aggregates at thermodynamic equilibrium with the free gas in the micropores. The resultant reaction/diffusion equation for pure gas movement in the aggregates is coupled with both Fickian diffusion of dissolved gas in water and free gas flow in the micropores along with the inorganic solid phase (clay, quartz, calcite) assumed impermeable. By postulating continuity of fugacity at the interface between free and dissolved gas in micropores and neglecting the water movement, we upscale the microscopic problem to the mesoscale, where both organic, inorganic solids and micropores are homogenized. The upscaling entails a new characteristic function which arises from the jumps in concentrations across the kerogen/micropore interface and leads to a new nonlinear pressure equation for gas hydrodynamics in the micropores including a new storage parameter strongly dependent on the total carbon content (TOC). When coupled with the nonlinear single phase gas flow in the hydraulic fractures the mesoscopic model leads to a new macroscopic triple porosity model with mass transfer functions between the different levels of porosity. Computational simulations illustrate the potential of the multiscale approach in numerically constructing accurate gas production curves in different regimes of gas flow.
Practical information
- General public
- Free