Analisis Gradien Resistivitas Magnetotelurik untuk Mendelineasi Zona Upflow di Lapangan Panas Bumi Mataloko, Nusa Tenggara Timur

Durotuzahro, Halifah (2026) Analisis Gradien Resistivitas Magnetotelurik untuk Mendelineasi Zona Upflow di Lapangan Panas Bumi Mataloko, Nusa Tenggara Timur. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Zona upflow merupakan target utama eksplorasi panas bumi karena berasosiasi dengan temperatur tinggi dan reservoir yang produktif. Ketepatan delineasi zona upflow menjadi aspek krusial mengingat tingginya biaya pemboran di Indonesia yang mencapai US$4–12 juta per sumur. Penelitian ini bertujuan mendelineasi zona upflow di Lapangan Panas Bumi Mataloko menggunakan analisis gradien resistivitas magnetotelurik yang diintegrasikan dengan gradien temperatur data sumur. Data yang digunakan meliputi 40 titik pengukuran MT yang tersebar pada 5 lintasan serta data temperatur dari tiga sumur eksplorasi, yaitu MT-2, MT-3, dan MT-4. Gradien resistivitas dihitung dari resistivitas semu invarian maupun dari hasil pemodelan inversi 2D menggunakan pendekatan regresi linier, kemudian dikonversi menjadi gradien temperatur melalui persamaan Arrhenius dengan konstanta yang diturunkan dari data sumur. Hasil analisis menunjukkan bahwa zona upflow utama terdeliniasi di sekitar Kawah Ratogesa dengan luas sebaran anomali gradien resistivitas tinggi sebesar ±0.51 km², terpusat pada titik BJE-250A dengan nilai gradien resistivitas semu tertinggi sebesar 0,5592 Ωm/m dan gradien resistivitas 2D tertinggi sebesar 0,00472 Ωm/m. Zona ini dikontrol oleh Sesar Wae Luja Muda yang bersifat tensional dan didukung oleh manifestasi permukaan bertipe fluida sulfat-asam dengan pH 2,93–4. Validasi menggunakan gradien temperatur menunjukkan nilai tertinggi sebesar 0,1076 °C/m yang berimpit secara spasial dengan anomali gradien resistivitas tinggi, dengan koefisien korelasi Pearson sebesar 0,888, sehingga mengonfirmasi konsistensi antara kedua parameter dan keandalan hasil delineasi zona upflow.
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The upflow zone is the primary target in geothermal exploration as it is associated with high temperatures and productive reservoirs. Accurate delineation of the upflow zone is crucial given the high drilling costs in Indonesia, reaching US$4–12 million per well. This study aims to delineate the upflow zone in the Mataloko Geothermal Field using magnetotelluric resistivity gradient analysis integrated with temperature gradient data from exploration wells. The data used include 40 MT measurement points distributed across 5 survey lines and temperature data from three exploration wells, namely MT-2, MT-3, and MT-4. Resistivity gradients were calculated from both invariant apparent resistivity and 2D inversion modeling results using linear regression, then converted to temperature gradients through the Arrhenius equation with constants derived from well data. The results indicate that the main upflow zone is delineated around the Ratogesa Crater, covering a high resistivity gradient anomaly area of approximately ±0.51 km², centered at station BJE-250A with the highest apparent resistivity gradient of 0.5592 Ωm/m and the highest 2D resistivity gradient of 0.00472 Ωm/m. This zone is structurally controlled by the tensional Wae Luja Muda Fault and is supported by surface manifestations of sulfate-acid fluid type with pH 2.93–4. Validation using temperature gradients shows a peak value of 0.1076 °C/m that spatially coincides with the high resistivity gradient anomaly, with a Pearson correlation coefficient of 0.888, confirming the consistency between both parameters and the reliability of the upflow zone delineation results.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Gradien Resistivitas, Gradien Temperatur, Inversi 2D, Magnetotelurik, Zona Upflow, Resistivity Gradient, Temperature Gradient, 2D Inversion, Magnetotelluric, Upflow Zone
Subjects:	Q Science > QE Geology Q Science > QE Geology > QE601 Geology, Structural
Divisions:	Faculty of Civil, Planning, and Geo Engineering (CIVPLAN) > Geophysics Engineering > 33201-(S1) Undergraduate Thesis
Depositing User:	Halifah Durotuzahro
Date Deposited:	23 Jul 2026 01:57
Last Modified:	23 Jul 2026 01:57
URI:	http://repository.its.ac.id/id/eprint/136304

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