11 ISSN 0125-9849, e-ISSN 2354-6638 Ris.Geo.Tam Vol. 30, No.1, Juni 2020 (11-20) DOI: 10.14203/risetgeotam2020.v30.1058 Numerical Modelling of Geothermal Reservoir in Gunung Talang, West Sumatera, Indonesia Lia Putriyana 1* , Hari Soekarno 1 1 Research and Development Center for Electricity, New & Renewable Energy, and Energy Conservation Technology, Ministry of Energy and Mineral Resources, Republic of Indonesia. Jl. Pendidikan No. 1, Pengasinan, Gunung Sindur, Bogor 16340 Indonesia ABSTRACT Gunung Talang geothermal field is a part of Gunung Talang – Bukit Kili geothermal working area, which is located in Solok Regency, West Sumatera, Indonesia, about 54 km to the northeast of Padang city. A numerical model consisting of 1,680 grid blocks, covering an area of 17 km 2 was developed for reservoir simulation. Two development strategies scenarios were constructed by considering various aspects such as reservoir behaviour, power plant’s lifetime, environmental effects, resources, and prospect area. The power plant’s power generation capacity and production lifetime of the scenarios are respectively 41,83 MW with 106 years production lifetime from the first scenario and 79,53 MW with 54 years production lifetime from the second scenario. Nowadays, the Gunung Talang – Bukit Kili geothermal working area is being auctioned with a potential power generation of 65 MW. Keywords: numerical model, geothermal reservoir. ABSTRAK – Pemodelan numerik reservoir panasbumi di Gunung Talang, Sumatera Barat, Indonesia. Lapangan panas bumi Gunung Talang merupakan bagian dari Wilayah Kerja Panasbumi Gunung Talang – Bukit Kili yang terletak di Kabupaten Solok, Sumatera Barat, Indonesia, sekitar 54 km arah timurlaut Kota Padang. Model numerik yang terdiri dari 1.680 blok grid untuk area seluas 17 km 2 dibuat untuk mensimulasikan reservoir. Dua skenario strategi pengembangan dibangun dengan mempertimbangkan beberapa aspek seperti perilaku reservoir, umur pembangkit, pengaruh terhadap lingkungan, sumber daya, dan area prospek. Kapasitas pembangkitan daya pembangkit listrik hasil skenario pertama adalah 41,83 MW dengan umur produksi 106 tahun, sedangkan skenario kedua menunjukkan kapasitas 79,53 MW dengan umur produksi 54 tahun. Saat ini, WKP Gunung Talang – Bukit Kili sedang dalam proses lelang dengan potensi pembangkitan listrik sebesar 65 MW. Kata kunci: model numerik, reservoir panasbumi. INTRODUCTION Geothermal resources estimation method plays an important role for the quantification of geothermal energy that can be produced under current technology and economic situation. The methods used for geothermal resources and reserves estimation are vary at different stages of geothermal development considering the information that may available. Previously, various methods have been used for assessing the extractable energy, including: (1) estimation of natural heat flow that represents the long-term sustainability of available energy; (2) analogies based on other fields that have been produced for Naskah masuk : 10 Mei 2019 Naskah direvisi : 24 Juni 2019 Naskah diterima : 30 Juni 2020 *Corresponding author. Email: lia.putriyana@gmail.com ©2020 Pusat Penelitian Geoteknologi Lembaga Ilmu Pengetahuan Indonesia