Open AccessMicroseismic and Focal Mechanism Analyses for Structural Interpretation – Muara Laboh Geothermal Field
Author(s) -
Djoko A. Wibowo,
Irvan Ramadhan,
Indra Nugroho,
Marino Baroek,
Novi Ganefianto,
Herwin Azis,
Suryantini,
David P. Sahara,
Prima Widianto Mozef
Publication year - 2022
Publication title -
iop conference series. earth and environmental science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.179
H-Index - 26
eISSN - 1755-1307
pISSN - 1755-1315
DOI - 10.1088/1755-1315/1014/1/012004
Subject(s) - geothermal gradient , induced seismicity , microseism , geology , seismology , borehole , hypocenter , fault (geology) , focal mechanism , petrology , geophysics , geotechnical engineering
Microseismic monitoring has been used for gathering subsurface information in Geothermal field as part of reservoir monitoring and management plan. New micro earthquake (MEQ) stations were installed in the Muara Laboh geothermal field in the end of 2019, coinciding with the first operation of Unit-1. They have been continuously used to monitor the MEQ events until now. This paper discusses MEQ data analyses to support the subsurface structural interpretation in the Muara Laboh geothermal field. Geothermal production and injection activities create micro seismicity which is triggered by stress failure in fractures / fault planes due to percolation of fluid within fractures network. Distribution of hypocenter locations and magnitude are analyzed, considering highly operational activities, rock mechanic and slip orientation. There are two micro seismicity clusters observed, namely South and North clusters. The South cluster represents 80% of the total recorded micro seismicity events, having NE – SW trend direction; while the North cluster consists of 10% of the total events, correlated with the NNW – SSE structural trend direction. Focal mechanism analysis explains that micro seismicity observed on extended fault zone in the south is thought to be correlated with the distributed fractured network on the hanging wall of normal fault. It is shown by some micro seismicity swarms identified in the south basin-sidewall fault area. These orientations support the current kinematic model of the Muara Laboh geothermal field derived from the structural geology mapping and borehole image logs.