Diffusion in surface-wetting films in a two-phase saturated porous solid characterised by pulsed magnetic field gradient NMR
✍ Scribed by William M. Holmes; Robin G. Graham; Ken J. Packer
- Publisher
- Elsevier Science
- Year
- 2001
- Tongue
- English
- Weight
- 168 KB
- Volume
- 83
- Category
- Article
- ISSN
- 1385-8947
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✦ Synopsis
Pulsed-field-gradient NMR measurements of the one-dimensional probability-density distribution P ∆ (X) for diffusive displacements of water molecules in times ∆ in a water-wet sandstone, saturated with a mixture of dodecane and brine, are presented for water saturations S w ≤ 0.32. The distributions show a distinctive shape which is attributed to the distribution of the aqueous phase in thin, locally curved and effectively two-dimensional layers on the pore surface. The data are reproduced well by a simple model in which diffusion is restricted to the surfaces of an isotropic array of infinite planes, with an effective diffusion coefficient D 2 (∆) which shows a systematic dependence on ∆. This is suggested to arise, in the main, from local curvature of the pore surface.