3D Geothermal Modelling Using Gravity Survey on Dolok Marawa, Simalungun District, North Sumatera

Padjadjaran Earth Dialogues: International Symposium on Geophysical Issues

Rivandi, A.^1 ; Destawan, R.^1 ; Fajri, Z.R.^1 ; Hidayat, W.^1

Geophysical Engineering Study Program, Faculty of Mineral Technology, UPN Veteran Yogyakarta, Indonesia^1

关键词: Bouguer anomaly;    Earth gravitational fields;    Geothermal modeling;    Gravity method;    Gravity survey;    Inverse modelling;    Measurement points;    Pyroclastic flows;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/29/1/012011/pdf
DOI  :  10.1088/1755-1315/29/1/012011

来源: IOP

【 摘 要 】

In North Sumatera, gravity method is applied to identify the geothermal model. This method measured the earth gravitational field. This research has 160 measurement points covering 9 square kilometers. We obtained complete Bouguer anomaly values ranging 85 mGal - 130.68 mGal interpreted as a heat source of andesitic igneous rocks that are affected by the presence of Mount Bahtopu magma chamber. We interpreted the values between 40 mGal - 80 mGal as reservoir and caprock. The 3D gravity inverse modelling conducted using Gravblox, and identifying the following lithologies; Toba Pyroclastic Fall (Qjt) with density 1.92 g/cm3, Toba Pyroclastic Flow (Qjt) with density 2.00 g/cm3, Mount Bahtopu Andesite (Qlb) with density 2.4 g/cm3, and 2.6 g/cm3which is interpreted as heat source in form of andesitic rock and Mount Bahtopu magma chamber. This heat source is estimated to be at a depth of 1.45 km to 3.78 km below the surface.