EXPLORATION OF STRATO-VOLCANIC GEOTHERMAL SYSTEMS (PARADIGMS)

Abstract

Successful development of high-T volcanic geothermal systems in developing countries for electric power generation is often restricted by inadequate and even fictitious conceptual models used during early and follow-up exploration phases. Adherence to these models can lead to the development of paradigms that, in turn, lead to prediction of unrealistic and exaggerated power potential estimates, even if poor or no evidence for a high-T system has been found. Political pressure (energy supply planning) can be a reinforcing paradigm agent.
The exploration history of countries with volcanic systems, such as African Rift countries and Pacific rim countries, provides examples for the development of such paradigms. Exploration of strato-volcano prospects in these settings provides some warning examples. In Indonesia strato-volcanic geothermal prospects have been explored assuming that they host a high-T reservoir. An extreme paradigm developed in Rwanda where a huge strato-volcano without any manifestations was assumed to be associated with a large, concealed, high-T geothermal reservoir. The paradigm overcame all non-supportive exploration results and was used to drill two, up to 3 km deep wells into ‘cold’ granitic basement.