Upscaling pore pressure-dependent gas permeability in shales

Global Upscaling of Permeability

Traditional upscaling methods depend on local boundary conditions. It is well known that this approach may introduce large errors in the coarse model. The new method is applicable whenever these local methods fail to produce an acceptable permeability field, e.g. upscaling of blocks close to wells and cases involving heterogeneities on the coarse grid block scale. In such cases, it is impossibl...

Analysis of Upscaling Absolute Permeability

Flow based upscaling of absolute permeability has become an important step in practical simulations of flow through heterogeneous formations. The central idea is to compute upscaled, grid-block permeability from fine scale solutions of the flow equation. Such solutions can be either local in each gridblock or global in the whole domain. It is well-known that the grid-block permeability may be s...

Improvement of Fracturing for Gas Shales

Low-temperature gas from marine shales

Thermal cracking of kerogens and bitumens is widely accepted as the major source of natural gas (thermal gas). Decomposition is believed to occur at high temperatures, between 100 and 200 degrees C in the subsurface and generally above 300 degrees C in the laboratory. Although there are examples of gas deposits possibly generated at lower temperatures, and reports of gas generation over long pe...

Gas hydrate-related sedimentary pore pressure changes offshore Angola

The thickness of the free gas column below the base of the gas hydrate stability zone is a proxy for the pore pressure in the free gas bearing sediments underneath. In the study area the pore over-pressrues derived under this assumption range between 0 and 1430 kPa ± 30% which appear to be the typical maximum over-pressure that the gas hydrate sediments can withstand before hydro-fracturing occ...