Natural State and Future Production Modelling of Arjuno-Welirang Geothermal Field, Indonesia

Abstract

Arjuno-Welirang geothermal field is one of the geothermal fields in Indonesia, located in Mojokerto Regency, East Java. It is a high terrain volcanic geothermal system, with a high reservoir temperature of 260oC. The upflow zone of the system is located around the peak of Mt. Welirang, indicated by the manifestation of several fumaroles. The outflow zones are located to the west and northwest of Mt. Welirang, indicated by several hot springs in the area. A number of conceptual models of Arjuno-Welirang geothermal field have been developed based on geological, geophysical, and geochemistry data. A new conceptual model is developed as a part of the present study to synthesise and enhance the existing conceptual models. A natural state numerical model is generated using AUTOUGH2 based on the conceptual model.
Three production scenarios were simulated with the model. The first scenario aims to maximise the output. The second scenario also aims to maximise output but with some restriction on well locations set by the perimeter of the National Park area. The third scenario is the same as the second except that the total number of make-up wells is reduced.