Permeability of granite under high pressure

Journal of Geophysical Research (1896-1977)Volume 73, Issue 6 p. 2225-2236 Permeability of granite under high pressure W. F. Brace, W. F. BraceSearch for more papers by this authorJ. B. Walsh, J. B. WalshSearch for more papers by this authorW. T. Frangos, W. T. FrangosSearch for more papers by this author W. F. Brace, W. F. BraceSearch for more papers by this authorJ. B. Walsh, J. B. WalshSearch for more papers by this authorW. T. Frangos, W. T. FrangosSearch for more papers by this author First published: 15 March 1968 https://doi.org/10.1029/JB073i006p02225Citations: 1,164AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Abstract The permeability of Westerly granite was measured as a function of effective pressure to 4 kb. A transient method was used, in which the decay of a small incremental change of pressure was observed; decay characteristics, when combined with dimensions of the sample and compressibility and viscosity of the fluid (water or argon) yielded permeability, k. k of the granite ranged from 350 nd (nanodarcy = 10−17 cm2) at 100-bar pressure to 4 nd at 4000 bars. Based on linear decay characteristics, Darcy's law apparently held even at this lowest value. Both k and electrical resistivity, ρs, of Westerly granite vary markedly with pressure, and the two are closely related by k = Cρs−1.5±0.1, where C is a constant. With this relationship, an extrapolated value of k at 10-kb pressure would be about 0.5 nd. This value is roughly equivalent to flow rates involved in solute diffusion but is still a great deal more rapid than volume diffusion. Measured permeability and porosity enable hydraulic radius and, hence, the shape of pore spaces in the granite to be estimated. The shapes (flat slits at low pressure, equidimensional pores at high pressure) are consistent with those deduced from elastic characteristics of the rock. From the strong dependence of k on effective pressure, rocks subject to high pore pressure will probably be relatively permeable. Citing Literature Volume73, Issue615 March 1968Pages 2225-2236 RelatedInformation