The effect of offset on fracture permeability of rocks from the Southern Andes Volcanic Zone, Chile

• DOI: 10.1016/j.jsg.2017.09.015
• Publication Date: 2017-09-30T04:33:06Z
• Authors: P. Pérez-Flores; G. Wang; T.M. Mitchell; P.G. Meredith; Y. Nara; V. Sarkar; J. Cembrano
• Keywords: Lithology

The Southern Andes Volcanic Zone (SVZ) represents one of the largest undeveloped geothermal provinces in world. Development potential requires a detailed understanding fluid transport properties its main lithologies. permeability SVZ rocks is altered by presence fracture damage zones produced Liquiñe-Ofqui Fault System (LOFS) and Andean Transverse Faults (ATF). We have therefore measured four representative lithologies from volcanic basement this area: crystalline tuff, andesitic dike, andesite granodiorite. For comparative purposes, we also samples Seljadalur basalt, an Icelandic rock with widely studied reported hydraulic properties. Specifically, present results systematic study effect fractures offsets on as function increasing effective pressure. Baseline measurements intact show that granodiorite has (10−18 m2), two orders magnitude higher than (10−20 m2). throughgoing mated macro-fractures increases between six magnitude, highest recorded for tuff. Increasing offset to produce unmated large up some characteristic value offset, beyond which changes only marginally. increase appears depend roughness aperture, these are different each lithology. Overall, fractured finite record values consistent those commonly found reservoirs (>10−16 potentially allow convective/advective flow develop. Hence, our demonstrate developed within permeable regions, especially transtensional NE-striking fault zones, major importance energy resource potential.