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Three-dimensional Magnetotelluric Inversion and Magnetic for The Characterization of The Geothermal Field Reservoir Zone “X” Asrowi, Ridho Hanan; Daud, Yunus; Ashadi, Abdul Latif; Hikmahtiar, Syouma; Said, Ahmad
International Journal of Hydrological and Environmental for Sustainability Vol 2, No 3 (2023): International Journal of Hydrological and Environmental for Sustainability
Publisher : CV FOUNDAE

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.58524/ijhes.v2i3.301

Abstract

Geothermal as an alternative energy source that is renewable and environmentally friendly has an important role in providing domestic energy needs. Exploration is one of the most important stages in the development of geothermal energy because it can minimize the risk at the stage of exploitation and development. Geophysical methods such as geomagnet and magnetotelluric are one of the methods used in exploration. Magnetic method can provide information on the description of rock demagnetization due to the presence of heat source. However, the magnetotelluric method will provide information about rock type resistance on geothermal fields. The existence of heat source using the geomagnetic method is represented by a low anomaly value as an indication of demagnetized rocks. The results of 3D inversion processing show a low value of type resistance in the area and form an updome. The correlation of the two results of processing the data can be seen in the southern part of the "X" geothermal field research area. Based on 3D Inversion modeling it can be seen the depth of the "X" Base of Conductor (BOC) geothermal system ranges from 1000 m to -800 m with resistivity ≤ 10 Ωm which is suspected as volcanic rocks. Geothermal reservoir is at a depth of 1000 m to -2000 m with a moderate resistivity of 40 - 60 Ωm which is suspected as an andesite volcanic rock, with temperature estimates ranging from 218o C to 255o C.
Investigation of Geological Structure Using Magnetotelluric and Gravity Data Optimization on Non Volcanic Geothermal, Bora, Centre of Sulawesi Pertiwi, Tiaraningtias Bagus; Daud, Yunus; Fahmi, Fikri
Journal of Geoscience, Engineering, Environment, and Technology Vol. 8 No. 02-2 (2023): Special Issue from The 1st International Conference on Upstream Energy Techn
Publisher : UIR PRESS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25299/jgeet.2023.8.02-2.13876

Abstract

The existence of geological structures is one of the important parameters in determining the permeability zone in a geothermal system. This research was conducted in a non-volcanic geothermal field, Bora, located in the province of Central Sulawesi, aiming to identify the subsurface features, especially geological structures related to permeability zones by optimizing geophysical data. Magnetotelluric (MT) 3D inversion modelling is some of the latest methods to identify geological structural patterns in geothermal systems. The results of the MT model and analysis its parameters can find variations in the distribution of subsurface resistivity, orientation of the direction of the prospect area, and indications of geological structure zones. The type and geometry of the geological structure associated with the high permeability zone can be complemented by determining the contrast of gravity values ​​and analysis of the maximum First Horizontal Derivative (FHD) and zero of the Second Vertical Derivative (SVD). Based on the analysis of geophysical data, it is possible to identify the permeability zone associated with the main structure, namely the Palu-Koro fault, delineate the geothermal reservoir at a depth of 1500-2000 meters and determine the location of well drilling. To visualize the geothermal system comprehensively, a conceptual model is developed by integrating the geophysical model with geological and geochemical data that are correlated with each other, therefore it can assist in determining the location of production well development.
Ambient Noise Data Processing to Obtain Group Velocity for Subsurface Structure Identification: Preliminary Research in Hululais Geothermal Field, Sumatra, Indonesia Tavip Dwikorianto; Daud, Yunus; Agustya Adi Martha; Aditya A Juanda
Journal of Geoscience, Engineering, Environment, and Technology Vol. 8 No. 02-2 (2023): Special Issue from The 1st International Conference on Upstream Energy Techn
Publisher : UIR PRESS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25299/jgeet.2023.8.02-2.13883

Abstract

Hululais area lies in the pull-apart basins of the Ketaun Segment and Musi Segment fault as a part of the Sumatra Fault Zone (SFZ). The boundary normal faults of pull-apart basins play an important role as major discharge zones for geothermal fluid because the extensional stress is concentrated in the boundary normal faults. In order to identify the geothermal reservoir structure in Hululais Geothermal Field (HGF), we introduce the local-scale study of the Rayleigh wave group velocity structure using ambient noise tomography (ANT). The ANT studies were collected using 18 seismometers inside 12 km2 area with a spacing of 125 – 500 meters, deployed across the fault structure for 1 month. More than two thousand Rayleigh Green’s Functions are extracted by cross-correlation at available station pairs. Using the estimated green function in this preliminary research, the group velocity as a function of the period can measure the dispersion curve by using multiple filter technique (MFT) and fast marching surface tomography (FMST) scheme to obtain group velocity images. The tomography result as group velocity image shows the subsurface Rayleigh wave structure variation. The NW-SE main structure is reflected by the contrast velocity structure between the central part and the north eastern-south western sides. The central part shows the low periods which are associated with low wave velocity However the margin of the central part shows the high velocity in all periods. The ANT studies have been efficient in time and cost, however useful in subsurface structure interpretation in Hululais Geothermal Field.