Experimental caracterisation of the relative gas permeability of very low permeability rocks
Résumé
The relative gas permeability (krg) of a low permeability caprock has been measured on a set of samples. The intrinsic gas permeability of the samples are typically in the order of 10-4-10-3 mD in the dry state at in-situ confining stress (9 MPa). Water saturations of the samples are achieved by equilibrating them in chambers whose relative humidities are imposed. The measured krg points lie on a main curve for all the samples and exhibit a very high critical gas saturation (Sgc) around 30% above which gas flow can be detected. The origin of this very specific behaviour is discussed using the percolation theory and an analogy with the krg curves shape observed during depletion tests. A possible explanation involves flow of gas as a discontinuous phase at gas saturations below Sgc during the percolation regime, leading to extremely low krg values with a plateau shape like in depletion tests.
Domaines
Sciences de l'ingénieur [physics]
Origine : Fichiers produits par l'(les) auteur(s)
Licence : CC BY - Paternité
Licence : CC BY - Paternité