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Magnetoteluric Modelling in High Noise of Low Frequency Signal LAESANPURA, AGUS; Larasati, Nindia E.; Sugianto, Asep; Yunian, Wahyu Eko
Indonesian Journal of Physics Vol 34 No 2 (2023): vol 34 no 2 2023
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itb.ijp.2023.34.2.6

Abstract

Magnetoteluric(MT) modelling geophysics in high noise areas is a challenging task. One part is the precious data for subsurface reconstruction, the other, the noise will a priori annoy the outcome. Through simulation and an example fact in the field, these two phenomena will be discussed. The simulation will propose the ideal model without and with noise, running on the Bostick inversion. Noise varies several schemas in two types of curves. Occam and Bostick algorithms will be used to run the inversion scheme. The trade of the advantages and disadvantages is then compared to a prior model in the field where MT data and geologic cross section are available. Two scenarios are available, one is to use data with treatment using available schema, and the other is to use data by cutting off the noise contaminant segment, and finally to see the resulted through 2D modelling process. The resultant shows the model use the ideal signal without noise through inversion resulting is a better than the other with a noisy signal experiencing treatment, notably in level shallow part. The geologic cross section and gravity model is available to support these results.
Integrative Analysis of the Geothermal Structure in Kepahiang: Insights from Magnetotelluric, Gravity, and Remote Sensing Techniques Larasati, Nindia E.; Laesanpura, Agus; Sugianto, Asep
Jurnal Penelitian Pendidikan IPA Vol 9 No 8 (2023): August
Publisher : Postgraduate, University of Mataram

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29303/jppipa.v9i8.4576

Abstract

This research was conducted to determine the structure and depth of the reservoir using remote sensing as an initial survey to assess the geological alignment direction, employing ALOS PALSAR radar imagery. Subsequently, further surveys were conducted using the magnetotelluric and gravity methods to analyze the structure and depth of the geothermal reservoir. The magnetotelluric data were processed using Phoenix software, where the data was transformed from the time domain to the frequency domain using Fourier transformation, and processed to obtain apparent resistivity and phase. The MT data was integrated with gravity data, and the gravity data underwent standard correction procedures to obtain the Complete Bouguer Anomaly (CBA) map. Two-dimensional (2D) inversion using the NLCG algorithm and 2D forward modeling of the gravity data were performed. The dominant alignment pattern obtained was northwest-southeast, with an orientation of 320° NW or 140° SE. Based on the results of geological alignment, a profile is produced that is perpendicular to the straightness. The results from the 2D inversion and gravity forward modeling indicated that the geothermal reservoir is likely located beneath the caprock at an estimated depth of approximately 1800 m, with resistivity values ranging from 32 to 256 Ohm-m and a density value is 2.6 gr/cc.