Tortuous pathways: Fundamental characterisation of the anisotropic permeability through clay-rich shales from macro- to nano-scale.
Abstract
The permeability of shales is important, because it controls where oil and gas resources can migrate to and where in the Earth hydrocarbons are ultimately stored. Shales have a well-known anisotropic directional permeability that is inherited from the depositional layering of sedimentary laminations, where the highest permeability is measured parallel to laminations and the lowest permeability is perpendicular to laminations. We combine state of the art laboratory permeability experiments with high-resolution X-ray computed tomography and for the first time can quantify the three-dimensional interconnected pathways through a rock that define the anisotropic behaviour of shales. Experiments record a physical anisotropy in permeability of one to two orders of magnitude. Two- and three-dimensional analyses of micro- and nano-scale X-ray computed tomography illuminate that the directional anisotropy is fundamentally controlled by the bulk rock mineral geometry, which determines the finite length (or tortuosity) of the interconnected pathways through the porous/permeable phases in shales. Understanding the mineral-scale control on permeability will allow for better estimations of the extent of recoverable reserves in shale gas plays globally.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFMMR44A..07M
- Keywords:
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- 1822 Geomechanics;
- HYDROLOGY;
- 3919 Equations of state;
- MINERAL PHYSICS;
- 3947 Surfaces and interfaces;
- MINERAL PHYSICS;
- 8010 Fractures and faults;
- STRUCTURAL GEOLOGY