AN UPDATED CONCEPTUAL MODEL OF THE TOMPASO GEOTHERMAL FIELD USING NUMERICAL SIMULATION

Abstract

Recent geoscience studies and well data suggest that the Tompaso geothermal field may have two separate reservoirs. The first reservoir is located around the LHD-27 well cluster in the Pinabetengan area and it has supplied 2×20 MWe at units 5 and 6 of the Lahendong power plant since the year 2016. The second prospect is located around the Tempang area, which is associated with the Soputan fault. A new conceptual assessment of the Tompaso area is presented based on a numerical reservoir model which was constructed using the TOUHG2 simulator and the EOS1 equation of state. The reservoir model includes two high-temperature upflows at the base of the model, including one below the Masam Crater and one below the Toraget area. The locations of these upflows were chosen based on the apprearance of alteration zones. A natural state model was developed based on downhole pressure and temperature data from ten wells. Based on this natural state model, an alternative conceptual model was proposed where the second geothermal prospect area was added. In the first prospect area, the updated conceptual model has the geothermal fluid coming from the upflow zone located below the Masam Crater and then moving north-northeast towards the Kawangkoan area. In the second prospect, the updated conceptual model has geothermal fluid flowing from an upflow zone under the Toraget area and expected moving to the northeast towards the Passo area.