3D conceptual modelling of the Abaya geothermal area, Ethiopia
Author: Paula Fernandez Acosta
Year: 2022
Supervisors: Juliet Ann Newson, Chelsea Arlette M. Cervantes
Abstract:
The Abaya geothermal field is located in the Southern Main Ethiopian Rift, a zone of continuing extensional tectonism and volcanic activity. Due to its location and through surface exploration, the existence of a large-scale geothermal reservoir in the area has been suggested. The main objective of this study is to integrate the geological, geochemical and geophysical data into a 3D conceptual model of the Abaya geothermal system. The Abaya system has not been drilled, so another more explored geothermal system is used to provide insights on processes in Abaya. The resulting models suggest that the permeability pathway of the Abaya field is given by a recharge of meteoric water coming from Damota Volcano located in the NNW. The fluid infiltrates the system through large near-vertical faults in a NNW-SSE direction, flowing close to the proposed deep electrical conductor located at 8 km depth, heating up and reaching the surface through the permeable fractures resulting in surface manifestations of springs and steaming grounds along SD-Hako Graben and Abaya fault. The conceptual model results indicate a shallow confined hydrothermal reservoir located in the SW of the Abaya area, between 160-2400 m depth with temperatures reaching 260 ºC. The results also match the resistivity data, where an increment is observed in resistivity from 1 m to 10 m presumably delineating the top part of the shallow reservoir. Furthermore, it is suggested that further studies and data of the subsurface are required to complement the surface exploration and to accurately characterize the Abaya geothermal system.