An Innovative Methodology Based on Low Frequency Passive Seismic Data Analysis to Map Geothermal Reservoir Steam Saturated Areas

Abstract

In the context of exploration, development and monitoring, it is highly valuable to have access to the steam saturated regions of a geothermal resource. During exploration phase, it consists of a strong evidence that a sufficiently hot system is still present before the drilling decision. Then it allows to identify the best locations for the future exploration and development wells. During the production phase, it is important to monitor the steam saturated area extension due to the field depletion (production induced reservoir pressure decrease) in order to optimize the positioning of the make-up wells. This work presents an innovative methodology to detect relevant reservoir steam saturated areas which can be applied at different stages of high enthalpy geothermal projects. A field survey was recently conducted in the Muara Laboh geothermal field. The obtained results were in complete agreement with observations made on all the exploration wells. They enable to map the extension of the potential steam saturated region at the top of the structure and also to identify another potential steam area associated with a secondary top. The identified steam cap extension remains to be confirmed by the development wells which will be drilled and tested during the course of this year. These preliminary results have demonstrated the applicability and the potential of this promising new steam detection method for high enthalpy geothermal resources.