| Title | Seismic Reflection Data and Conceptual Models for Geothermal Development in Nevada |
|---|---|
| Authors | Glenn Melosh, William Cumming, John Casteel, Kim Niggemann and Brian Fairbank |
| Year | 2010 |
| Conference | World Geothermal Congress |
| Keywords | Blue Mountain, Pumpernickel, reflection seismic, geothermal exploration |
| Abstract | Seismic reflection data were collected in two geothermal areas in Nevada to support geologic structural models and geothermal well targeting. The data were integrated with surface mapping, well results, and other geophysical data in conceptual geologic models in both areas. Faults were interpreted from reflection data based on reflector offsets and apparent fault surface reflectors dipping away from the range front. Interpreted faults at Blue Mt., where several wells have been drilled, correlated with well entries. Subsequent well targeting based on the conceptual structural model at Blue Mt. resulted in an important step-out drilling success. The data quality in reflection images with possible fault surface reflectors was reviewed because of the potential exploration value of the correlation of these reflectors with well entries. Data quality review at Blue Mt. showed that noise patterns dominate most of the reflection data. Consequently it appears that the interpreted fault surface reflectors are most likely related to coherent noise and that the observed well entry – fault correlations may be fortuitous. The noise review experience from Blue Mt. has been integrated into more successful seismic interpretations elsewhere, including at the Pumpernickel Prospect. The application of reflection data in Basin and Range settings should consider noise issues at the design and interpretation stage, use quality assurance graphics to assess interpretation uncertainty, interpret the reflection data in the context of the refraction seismic velocity images, and apply skepticism to apparent fault reflectors dipping away from the range front. The success of the step-out well targeting at Blue Mt. in spite of the failure of seismic reflection data to image the subsurface demonstrates the robust reliability of a conceptual model approach to geothermal exploration that emphasizes the consistent integration of multiple data sets. |