Pemodelan Inversi 3D Struktur Bawah Permukaan Area Panas Bumi Way Selabung, Sumatera Selatan Berdasarkan Data Magnetotellurik

Ginting, Yosi Asrolinawaty (2023) Pemodelan Inversi 3D Struktur Bawah Permukaan Area Panas Bumi Way Selabung, Sumatera Selatan Berdasarkan Data Magnetotellurik. Other thesis, Insititut Teknologi Sepuluh Nopember.

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Abstract

Lokasi Penelitian berada di lapangan panas bumi Way Selabung, Provinsi Sumatera Selatan. Metode Magnetotelurik (MT) memiliki peranan penting dalam eksplorasi geotermal, dikarenakan dapat menghasilkan data distribusi nilai resistivitas dengan kedalaman yang cukuptinggi. Dalam penelitian ini, digunakan 30 titik MT. Adapun, tujuan pemodelan inversi 3D dataMagnetotelurik digunakan untuk mengurangi ambiguitas data pada Magnetotelurik inversi 1Ddan 2D. Salah satu, faktor dari ambiguitas data pada inversi 2D dikarenakan bentuk dan tatananbumi yang kompleks sehingga dibutuhkan pemodelan yang lebih detail maka pada penelitian ini digunakannya pemodelan inversi 3D sebagai cross check dari inversi 2D. Pemodelan inversi1D, 2D, dan 3D dilakukan dengan menggunakan WinGlink dan Surfer. Data MT yang diperoleh dari akuisisi lalu dilakukan pengolahan dengan tahapan berikut: konversi domain waktu ke domain frekuensi, pemilihan crosspower, data smoothing, koreksi efek statis, 2D danstatic shift, interpolasi, masking, dan 3D Inversion, serta interpetasi model inversi. Inversi model 3D terdiri dari parameter grid 3D mesh. Pemodelan Inversi 2D dilakukan dengan metodeNLCG dengan menggunakan nilai tau 3 dan RMS error 2,1 %. Dari hasil pemodelan inversi 2D sistem panas bumi Way Selabung diperkirakan lapisan penudung atau caprock dengan rentang nilai tahanan jenis 10 Ωm – 52 Ω pada kedalaman 1250 km, lapisan reservoir pada zona resistivitas tengah dengan nilai tahanan jenis 65 Ωm – 512 Ωm, dan zona resistivitas tinggi dengan nilai 630 Ωm – 5000 Ωm yang berperan sebagai heat source. Dari hasil pemodelan inversi 3D menunjukkan adanya dua tubuh vulkanik yang berperan sebagai sumber dari manifestasi yang terdapat di area panas bumi yaitu tubuh vulkanik Tebat Gayat dan Akarjangkang serta adanya pengaruh besar dari area depresi atau Graben pada sistem panas bumi ini. Sehingga dapat disimpulkan sistem panas bumi area penelitian adalah vulkano – tektonik, dengan ketebalan lapisan caprock 500 − 1500 km berupa batuan Piroklastik ranau dan terdapat zona Upflow pada Sesar Way Selabung, Sesar Akarjangkang, dan Sesar Kota Dalam.
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The research location is in the Way Selabung geothermal field, South Sumatra Province. The Magnetotelluric (MT) method has an important role in geothermal exploration, because it can produce resistivity value distribution data with a fairly high depth. In this study, 30 MT points were used. Meanwhile, the purpose of modeling the inversion of 3D Magnetotelluric data is used to reduce the ambiguity of data on Magnetotelluric inversion 1D and 2D. One of the factors of data ambiguity in 2D inversion is due to the complex shape and order of the earth so that more detailed modeling is needed, so in this study 3D inversion modeling is used as a cross check of 2D inversion. 1D, 2D, and 3D inversion modeling is done using WinGlink and Surfer. MT data obtained from the acquisition is then processed with the following stages: conversion of time domain to frequency domain, crosspower selection, data smoothing, correction of static effects, 2D and static shift, interpolation, masking, and 3D Inversion, as well as interpretation of inversion models. The inversion of the 3D model consists of the parameters of the 3D mesh grid. 2D Inversion modeling was carried out using the NLCG method using tau value 3 and RMS error 2.1%. From the results of 2D inversion modeling of the WaySelabung geothermal system, it is estimated that the caprock layer with a range of resistance values of type 10 Ωm - 52 Ω at a depth of 1250 km, the reservoir layer in the middle resistivity zone with a type resistance value of 65 Ωm - 512 Ωm, and a high recitivity zone with a value of 630 Ωm - 5000 Ωm which acts as a heat source. From the results of 3D inversion modeling shows the existence of two volcanic bodies that act as sources of manifestations found in geothermal areas, namely the volcanic bodies of Tebat Gayat and Akarjangkang and the major influence of the depression or Graben area on this geothermal system. So it can be concluded that the geothermal system of the study area is volcanic - tectonic, with a caprock layer thickness of 500 − 1500 km in the form of ranau pricostatic rock and there
are Upflow zones on the Selabung Way Fault, Akar Jangkang Fault, and Kota Dalam Fault.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Magnetotellurik, Inversi 3D, Geothermal, Way Selabung, Magnetotelluric, 3D Inversion.
Subjects:	G Geography. Anthropology. Recreation > G Geography (General) > G70.212 ArcGIS. Geographic information systems.
Divisions:	Faculty of Civil, Planning, and Geo Engineering (CIVPLAN) > Geophysics Engineering > 33201-(S1) Undergraduate Thesis
Depositing User:	Yosi Asrolinawaty Ginting
Date Deposited:	15 Sep 2023 07:35
Last Modified:	15 Sep 2023 07:35
URI:	http://repository.its.ac.id/id/eprint/104456

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