Delineation of Near Surface Water Flow Path of Wahawa Geothermal Field by Using 2D Inversion of Resistivity Data

摘要

The Wahawa geothermal field which is located in the Eastern province of Sri Lanka has an average temperature of 60°C in its surface manifestations. Since the temperature is considerably high, it is important to explore the feasibility of direct utilization of the energy of this geothermal field. In the present study, electrical resistivity measurements were employed in a 20 km2 region in order to delineate the Wahawa geothermal system and to understand the near-surface fracture pattern. Electrical resistivity mapping of the region has been carried out using Schlumberger array measurements with nominal current array spacing (half spacing) of 150 m and it was observed that there was a path of low ( W) apparent resistivity. These results revealed that the hotsprings resting on a hard rock terrain are presumably composed of metamorphic rocks, suggesting lateral movement of hotwater towards the hotsprings instead of a deep-influx. The area of surface manifestations is not suitable for utilization application due to clustering of the main feeding path. The major hotwater feeding path which is extending in the west direction can be recommended as a possible drilling target for direct utilization applications.