Magnetotelluric-Geochemistry Investigations of Blawan Geothermal Field, East Java, Indonesia

Sukir Maryanto,Vanisa Syahra,Arief Rachmansyah,Ahmad Nadhir,Didik R Santoso,James Foster,Cinantya N Dewi

doi:10.3390/geosciences7020041

Sukir Maryanto, Vanisa Syahra + Show 5 more

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https://doi.org/10.3390/geosciences7020041

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Journal: Geosciences	Publication Date: Jun 10, 2017
Citations: 12	License type: CC BY 4.0

Affiliation: University of Brawijaya, University of Hawaii System

Abstract

An integrated magnetotelluric (MT) and geochemical study of the Blawan geothermal field has been performed. The character of the hot springs, the reservoir temperature, and geothermal reserve potential of Blawan geothermal field are assessed. MT measurements, with 250 m up to 1200 m spacings, were made at 19 sites, and 6 locations at the Blawan hot springs have been sampled for geochemical survey. The results of 2D modelling indicated that the geothermal system in the research area consisted of a cap rock zone (≤32 Ω•m), reservoir zone (>32 – ≤512 Ω•m), and heat source zone (>512 Ω•m), and also identified faults. The characteristics of the hot spring water were identified through analyzing the major and minor elements. A ternary diagram (Cl-SO4-HCO3) showed that the Blawan hot springs consist of bicarbonate water (at locations of AP-01, AP-02, AP-03) and chloride water (at locations of AP-04, AP-05, and AP-06), with a reservoir temperature of approximately 90 °C based on the Na–K–Ca geothermometer results. An estimate of the geothermal energy using the volumetric method, gave a total geothermal reserve potential of 1.823 MWe.

Highlights

Indonesia contains about 40% of the global geothermal potential with about 80% of it being volcano-hosted geothermal, as Indonesia has 127 volcanoes—or about 13% of volcanoes around the globe [1,2,3]
Blawan area is a caldera lake sitting on volcanic deposits with an abundance of pumice which formed sandstone and presenceofofgeothermal geothermal potential at location this location is characterized formed sandstone andsilt
Variousgeophysics geophysics investigations hot springs springs scattered scattered in investigations havehave beenbeen carried out out in Blawan since to understand thethe geothermal characteristics carried in Blawan since to understand geothermal characteristicsand andresources resourcesin inthe thearea

Summary

Introduction

Indonesia contains about 40% of the global geothermal potential with about 80% of it being volcano-hosted geothermal, as Indonesia has 127 volcanoes—or about 13% of volcanoes around the globe [1,2,3]. There are 265 identified geothermal energy locations with a total potential of 28.1 GWe. Most of the potential is associated with volcanic lines, which generally has high enthalpy, and can be commercially developed for power generation. A small portion of geothermal sources are associated with non-volcanic systems, and usually have a relatively low temperature reservoir. Geothermal systems in Indonesia can generally be divided into five types based on the geological structure which is a predictor for the magnitude of its potential: volcano complexes and graben—caldera volcanic cones—generally have a potential energy that is much larger than the other types.

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