Reservoir Identification Based on Gravity Method at “AUN” Geothermal Field

Annisa Dwi Hafidah,Yunus Daud,Alfian Usman,Hadiyanto Hadiyanto,Maryono Maryono,Budi Warsito Budi Warsito

doi:10.1051/e3sconf/201912514008

Annisa Dwi Hafidah, Yunus Daud + Show 4 more

Open Access

https://doi.org/10.1051/e3sconf/201912514008

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Abstract

Sumatra Island has the largest geothermal potential in Indonesia spread along the subduction zone between the Indian-Australian plate and the Eurasian plate. “AUN” geothermal field located in Sumatra Island and considered to be one of the largest potential geothermal prospects in Indonesia. This study is focused on identifying the prospect of “AUN” geothermal field using gravity method. First Horizontal Derivative (FHD) and Second Vertical Derivative (SVD) analysis were applied in order to determine a more accurate boundary of the fault. 3D inversions of gravity data were used to reconstruct subsurface model. The result show that analysis of First Horizontal Derivative (FHD) and Second Vertical Derivative (SVD) can confirm southwest-northeast fault and caldera structure as a boundary of geothermal reservoir and 3D gravity inversion can show subsurface layers with density 2.5 gr/cc to 2.8 gr/cc inside the boundary which is determined as a heat source in “AUN” geothermal field.

Highlights

Sumatra Island has the largest geothermal potential in Indonesia spread along the subduction zone between the Indian-Australian plate and the Eurasian plate [1]
First Horizontal Derivative (FHD) and Second Vertical Derivative (SVD) analysis were applied in order to determine a more accurate boundary of the fault [4]
The gravity measurement was conducted at 399 stations which are distributed in the area to delineate the existence of the geothermal system

Summary

Introduction

Sumatra Island has the largest geothermal potential in Indonesia spread along the subduction zone between the Indian-Australian plate and the Eurasian plate [1]. “AUN” geothermal field located in Sumatra Island and considered to be one of the largest potential geothermal prospects in Indonesia. Several surface thermal manifestations, such as fumaroles and hot springs, were found. The appearance of these manifestations is probably caused by the permeable pathway due to the intersection of several geological structures. This study is focused on identifying the prospect of “AUN” geothermal field using gravity method. Gravity method can provide information related to density distribution in the subsurface which will be used to identify faults in the geothermal prospect area [3]. The 3D inversion of gravity data was used to reconstruct subsurface model so that the reservoir zone in “AUN” geothermal field can be identified

Data Processing

Result

Separation of Regional and Residual Anomaly

Derivative Analysis

Conclusion