A PARSIMONIOUS APROACH FOR SUBSURFACE TEMPERATURE ESTIMATION BASED ON MAGNETOTELLURIC (MT) DATA FROM WAE SANO GEOTHERMAL FIELD: PENDEKATAN PARSIMONI UNTUK ESTIMASI TEMPERATUR BAWAH PERMUKAAN BERDASARKAN DATA MAGNETOTELLURIK (MT) DARI LAPANGAN GEOTERMAL WAE SANO

Iqbal Takodama; Tony Rahadinata; Hendra Grandis

doi:10.47599/bsdg.v21i1.594

Authors

Iqbal Takodama Pusat Sumber Daya Mineral Batubara dan Panas Bumi, Indonesia Author
Tony Rahadinata Pusat Sumber Daya Mineral Batubara dan Panas Bumi, Indonesia Author
Hendra Grandis Institut Teknologi Bandung, Indonesia Author

DOI:

https://doi.org/10.47599/bsdg.v21i1.594

Keywords:

Resistivity Gradient, Temperature Gradient, Bostick Transformation, Arrhenius Equation, Wae Sano

Abstract

The magnetotelluric (MT) method is widely used in geothermal exploration to delineate conductive zones commonly interpreted as clay cap. However, this conductive zone does not always represent high temperatures, often leading to interpretational ambiguity. This study proposes a parsimonious Arrhenius-based approach to estimate subsurface thermal gradient from resistivity gradients derived from apparent resistivity analysis and Bostick transformation. The method was applied to 102 MT stations in the Wae Sano field and calibrated using temperature logs from two gradient thermal wells. Results show a strong linear correlation (R² = 0.996) with an RMSE of ~8%. The temperature model reveals a ~225°C dome-shaped isotherm at 500 - 750 m depth in the southeastern sector of Lake Sano Nggoang, interpreted as an upflow zone. This approach provides an efficient rapid-assessment tool for early-stage geothermal prospect delineation and supports optimization of MT survey design during preliminary exploration.

Author Biography

Iqbal Takodama, Pusat Sumber Daya Mineral Batubara dan Panas Bumi, Indonesia

Tim Panas Bumi - Pusat Sumber Daya Mineral Batubara dan Panas Bumi

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