The Subsurface Modelling of Karaha-Telaga Bodas Geothermal System using Gravity Method

2nd Southeast Asian Conference on Geophysics

Yosephin, Missela^1 ; Santoso, Djoko^2 ; Setianingsih^2

Undergraduate Program of Geophysical Engineering, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Ganesha 10, Bandung

40132, Indonesia^1

Applied and Exploration Geophysics Group, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Ganesha 10, Bandung

40132, Indonesia^2

关键词: Drilling operation;    Forward modeling;    Geological information;    Geothermal systems;    Karaha-Telaga Bodas;    Spectral filtering methods;    Subsurface model;    Two-dimensional cross sections;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/318/1/012037/pdf
DOI  :  10.1088/1755-1315/318/1/012037

来源: IOP

【 摘 要 】

The Complete Bouguer Anomaly (CBA) map from 1997 gravity survey at Karaha-Telaga Bodas, West Java, Indonesia is used to make a model of the subsurface geothermal system. A two-dimensional cross-section of the system is produced using a 2.5-D forward modeling. Initially, the print CBA maps of the Karaha-Telaga Bodas geothermal system is digitized. Next, the digital map is separated by using the moving average and spectral filtering methods, so a regional and residual anomaly maps are obtained. The subsurface modelling is made based on geological information of the area to produce a model that can represents the real condition as similar as possible. The line chosen for modelling has a North - South orientation, passing through Karaha and Telaga Bodas to foresee both of the geothermal system in one cross-section. Subsurface model interpretation shows that there are two separate granodiorite intrusion body with density contrast of 0.5 g/cc below Karaha - Telaga Bodas. This conclusion coincides with the intrusion body found during drilling operation. The intrusion body is possibly the heat source of the system. The reservoir of this system is interpreted as volcanic breccia with thickness of two kilometres in Telaga Bodas and keeps thinning towards Karaha. The fluids of the Karaha-Telaga Bodas Geothermal System are estimated to come from acid sulphate water and meteoric water entering from Telaga Bodas, as well as meteoric water entering from Karaha. There is an upflow in the South, Telaga Bodas.