Pemodelan Inversi 2-D Data Magnetotelurik Pada Lapangan Panas Bumi "Basri" Sulawesi Barat

Al Bashri, Alif (2018) Pemodelan Inversi 2-D Data Magnetotelurik Pada Lapangan Panas Bumi "Basri" Sulawesi Barat. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Lapangan panas bumi “Basri” secara geologi terbentuk akibat aktifitas sesar geser yang menciptakan gawir sesar yang berbentuk setengah radial dan menimbulkan zona depresi. Heat source diperkirakan dari sisa panas dapur magma yang berasosiasi dengan aktivitas plutonik muda berumur kuarter. Metode magnetotelurik mengukur di daerah lapangan panas bumi dengan sebaran titik ukur berjumlah 19 titik dengan total lintasan pengukuran sebanyak enam lintasan. Lintasan satu sampai dengan tiga mempunyai arah lintasan barat laut – tenggara dan lintasan empat sampai dengan enam mempunyai arah lintasan barat daya – timur laut. Tahapan pengolahan meliputi konversi data domain waktu menjadi domain frekuensi, seleksi crosspower, proses smooting data, koreksi efek static, parameterisasi inversi 2-D, dan interpretasi model inversi. Pemodelan data magnetotelurik menggunakan metode inversi Non Linear Conjugate Gradient (NLCG) menghasilkan model inversi magnetotelurik 2-D. Nilai RMS pada masing – masing model inversi secara keseluruhan dibawah 2,5 %. Hasil akhir model inversi diinterpretasikan menggunakan parameter berupa nilai resistivitas dan informasi geologi. Nilai resistivitas dengan rentang nilai 20 – 50 ohm meter diperkirakan sebagai lapisan cap rock, nilai 100-250 ohm meter diduga sebagai lapisan reservoir panas bumi, diatas 250 ohm meter diprediksi sebagai lapisan heat source. Lapisan cap rock menebal kearah barat laut dan timur laut dengan ketebalan bervariasi dari 100 – 1500 meter, lapisan reservoir mempunyai ketebalan konstan sebesar 500 meter dan lapisan heat source menebal kearah tenggara dan timur laut dengan ketebalan lebih dari 2000 meter. ============================================================================================== The geothermal system in Basri area is formed by shear fault activities that created a half-size radial fault scarps and creates a depression zone. Heat source is estimates from the remaining of magma chamber’s heat and it associations with quarter plutonic activities. Magnetotelluric method measures 19 point MT in the geothermal system field with 6 line measurement. Line 1 until 3 has a northwest – southeast direction and line 4 until 6 has a southwest – northeast direction. The processing step of magnetoteluric are consist of time domain convertion to frequency domain, crosspower selection, smoothing data, static effect correction, parameterization of 2-D Inversion, and interpretation of inversion model. Modeling of magnetoteluric data using Non Linear Conjugate Gradient inversion method and it creates a two dimensional inversion of magnetoteluric. All of value RMS in inversion’s models are below 2,5 % . The interpretation of inversion’s model is using resistivity value and geological information. A resistivity value with a range 20 until 50 ohm meter is estimated as cap rock zone, 100 until 250 ohm meter suspected as reservoir zone, and above 250 ohm meter predicted as heat source zone. Cap rock zone thickening towards the northwest and northeast with 100 – 1500 meters, reservoir zone has a constant thickness of 500 meters, and heat source thickening towards the south easth and north easth more than 2000 meters

Item Type: Thesis (Undergraduate)
Uncontrolled Keywords: inversi NLCG, magnetotelurik, model inversi 2-D
Subjects: G Geography. Anthropology. Recreation > GB Physical geography > GB1197.7 Groundwater flow. Reservoirs
G Geography. Anthropology. Recreation > GE Environmental Sciences
Q Science > Q Science (General) > Q180.55.M38 Mathematical models
Q Science > QE Geology > QE601 Geology, Structural
Divisions: Faculty of Civil Engineering and Planning > Geophysics Engineering > 33201-(S1) Undergraduate Thesis
Depositing User: Alif Al Bashri
Date Deposited: 21 Jul 2021 22:20
Last Modified: 21 Jul 2021 22:20
URI: https://repository.its.ac.id/id/eprint/57218

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