Stress, Fracture, and Fluid-flow Analysis Using Acoustic and Electrical Image Logs in Hot Fractured Granites of the Coso Geothermal Field, California, U.S.A.

摘要: Acoustic and electrical image logs in fractured granitic rocks penetrated by U.S. Navy well 58A-10, Coso Wash," the eastern margin of geothermal field, California, were compared to evaluate their relative ability characterize fractures fault rock textures measure stress orientations from borehole failure. Electrical are sensitive variations mineralogy or porosity, which affect conductivity. Thus, they capture both open healed natural as foliation. In acoustic logs, faults principally revealed increased roughness wall impedance contrasts caused microcrack density hydrothermally altered rock. reveal fabric relatively poorly while favoring well-developed zones. These tools thus complementary fracture characterization benefits using both. Drilling-induced structures such breakouts tensile that form at petal-centerline just ahead floor record orientation principal stresses. Although types produce good images drilling-induced fractures, superior recording distribution geometry because a full 360 reflectivity radius. Analyses repeat temperature zones localized fluid flow coincide with large visible logs. characterized distinctive brittle texture oriented for slip.