Techniques For Geothermal Exploration Research Articles

The application of day and night time ASTER satellite imagery for geothermal and mineral mapping in East Africa

There is considerable interest in optimizing geothermal exploration techniques via the mapping of alteration and evaporate mineralisation, as well as of thermal emissions associated with geothermally active areas on the Earth’s surface. Optical and thermal satellite sensor technologies, improvements in processing algorithms and the means for large scale (e.g. 1:250,000) spatial data distribution are required for detecting both these attributes. The extensive visible, -near, -shortwave and thermal infrared (VNIR-SWIR-TIR) data archive acquired by the multi-spectral Advanced Spaceborne Thermal Emission Reflectance Radiometer (ASTER) provides a rich source of geoscience related imagery for geothermal exploration. Examples of generating large scale mosaicked ASTER imagery to provide province to continental mineral mapping have been undertaken in areas including such as Australia, western USA, Namibia and Zagros Mountains Iran. In addition, ASTER’s thermal infrared imagery also provides night time land surface temperature (LST) estimates relevant for detecting possible geothermal related anomalies.This study outlines existing methods for the application of ASTER data for geothermal exploration in East Africa. The study area encompasses a section of the East African Rift System across the Tanzanian and Kenyan border. The area includes rugged volcanic terrain which has had geological mapping of limited coverage at detailed scales, from various heritages and mapping agencies. This study summarizes the technology, the processing methodology and initial results in applying ASTER imagery for such compositional and thermal anomaly mapping related to geothermal activity. Fields observations have been used from the geothermal springs of Lake Natron, Tanzania, and compared with ASTER derived spectral composition and land surface temperature results. Published geothermal fields within the Kenyan portion of the study area have also been incorporated into this study.

English

Geothermal power is one of the safest and environment friendly energy worldwide. It has been harvested in Kenya since 1956 with most potential sites being along the Rift Valley. There are surface manifestations such as hot springs and mudpools that are visible. Different methods of exploration are usually applied, including geophysical, geochemical and geological methods. This paper highlights different geothermal exploration techniques with emphasis on low cost methods that can be used in developing countries to map geothermal potential areas highlighting methods used in Kenya. A comparable cost analysis is done for Olkaria field in Kenya which has been explored using different methodologies and the results show that ground survey methods are more expensive than remote sensing though the two methods have unique advantages. Ground data collection method is three times expensive as compared to the remote sensing methodology. It also reviews the geothermal indicators that can be mapped by remote sensing techniques, and especially those using satellite imagery. Key words: Geothermal indicators, exploration, geographical information systems (GIS), remote sensing.

Geothermal resources assessment in Hawaii

Report prepared for Western States Cooperative Direct Heat Resource Assessment under grant No. DOE DE-ACO3-80SF10819, Feb. 1985.

Gravity Study of the Fumarole Butte Area, Juab and Millard Counties, Utah

A gravity survey was made in 1973 of the Fumarole Butte area, including the Crater Springs KGRA (Baker Hot Springs), located approximately 39 km (22 miles) NW of Delta, Utah. About 500 stations were taken as part of a study of geothermal exploration techniques. The region of investigation includes portions of both Juab and Millard Counties and incorporates parts of the Desert, McDowell and Drum Mountains. A simple Bouguer gravity anomaly map was computed and two-dimensional geologic models were prepared for two east-west gravity profiles. The analysis of the gravity data, in conjunction with the known geology and the results from other geophysical studies, led to the following interpretations: 1) the indication of two buried intrusive bodies - one a north north westward-trending dike lying beneath the Baker Hot Springs and the eastern margin of the Fumarole Butte lava flows and another several miles southwest of Desert Mountain; 2) the delineation of previously ' unpublished Basin and Range faults and associated grabens; and 3) the existence of a basement flexure with postulated fractures that served as conduits for the upwelling magma to reach the surface at Fumarole Butte.