| Title | Remote Detection of Active Faults Using Borehole Breakouts in the Heber Geothermal Field, Imperial Valley, California |
|---|---|
| Authors | Allison, M. Lee |
| Year | 1990 |
| Conference | Geothermal Resources Council Transactions |
| Keywords | Exploration; Drilling; USA; California; Imperial; Heber; Geology; Faults; Logs; Electrical Logs; Thermal Stress; Temperature Gradient; Borehole Breakout; Dipmeter |
| Abstract | Analysis of borehole breakouts from wells in the Heber geothermal field in the southern Imperial Valley of California reveals three broadly defined breakout orientations: north-south (azimuth range 350-10 degrees), NW-SW (35-70 degrees), and WNW-ESE (70-130 degrees). Wells closest to faults are dominated by breakout orientations expected for extensional faults of those directions. Thermal gradient maps confirm an east west trending thermal anomaly apparently truncated to the east against the Imperial Fault. The breakout data suggests that this anomaly is a manifestation of a hydrothermally active fracture system not presently being produced. Mapping the relative density of local breakout trends offers the potential of identifying the location and orientation of hydrothermal and other active faults and fractures. |