History of geothermal exploration in Indonesia from 1970 to 2000
Introduction
Geothermal exploration in Indonesia began in 1970 with the aim of finding and developing high-temperature geothermal systems. The developments between 1970 and 1990 (in many cases until 1995) are not well documented. An attempt is made here to summarize the early surveys, referring to information in publications and reports written in English, mainly by Indonesian scientists and engineers, which are accessible in the public domain. Thus, the exploration of prospects is discussed where detailed geological, geochemical, and geophysical methods were combined to assess field characteristics of importance when siting exploration wells over inferred high-temperature reservoirs. Results of early geophysical surveys are discussed in more detail where they led to proper estimates of reservoir areas and, combined with important geochemical and geological findings, allowed a prediction of reservoir characteristics. Since most of the earlier exploration efforts are not listed in the scientific literature, theses and diploma reports of Indonesian geothermal graduate students attending the University of Auckland between 1979 and 2003 became an important source of information and were used for this paper. The geothermal terminology employed here is that adopted in Hochstein and Browne (2000). The description of a few prospects not covered by published work is based on observations and field notes collected by the authors.
Descriptions of Indonesian geothermal resources probably started with the reconnaissance surveys described by Junghuhn over 150 years ago (Junghuhn, 1854), whose studies covered mainly active volcanoes and large thermal areas on Java. From around 1900 until the beginning of World War II, most of the Indonesian Quaternary volcanoes and their fumarole and solfatara fields were mapped by the Dutch colonial Geological Survey; the results were later published in the first volume of the Catalogue of the Active Volcanoes of the World (Neumann van Padang, 1951). A summary of documented thermal springs on Java, the Molucca Islands, and Sumatra can be found in the lists of global thermal springs by Waring (1965). After Indonesia gained independence, the Volcanological Survey of Indonesia (VSI) started work in the 1960s with reconnaissance-type surveys that led to the compilation of an inventory of sites with thermal manifestations. A map showing the location of these sites on Java and Bali was compiled by VSI in 1968 (Purbo-Hadiwidjojo, 1970). The studies were supported by the State Electricity Company (PLN) and the Bandung Institute of Technology (ITB). International and foreign missions (UNESCO, EURAFREP) visited several geothermal prospects at that time and, with reference to the size and type of manifestations, drew attention to prospects associated with hot spring discharges. A revised catalogue of volcanoes and fumarole fields in Indonesia published by VSI (Kusamadinata, 1979) provided important information now incorporated in a world-wide catalogue of volcanoes that can be accessed through the Smithsonian volcano website (see bottom of Table 1).
All Indonesian geothermal systems associated with surface manifestations discharging fluids at boiling temperature occur in areas with Quaternary volcanism and active volcanoes along well-defined volcanic arcs. There are five active arc segments in Indonesia that define regions of interest for geothermal exploration (Fig. 1). Using plate tectonic concepts, all active Indonesian arcs can be interpreted as the result of sub-crustal melting induced by subducted lithosphere plates (Katili, 1975). The major plate tectonic structures shown in Fig. 1 had already been recognised during the 1970s (Hamilton, 1979). All young Quaternary volcanoes can be associated with cooling magma and igneous intrusions, which, in turn, are heat sources for active arc-type geothermal systems.
The first inventory (in English) of Indonesian thermal areas and prospects, compiled by VSI as part of a New Zealand (NZ) Aid project in 1987 (NZMFA, 1987, Mahon, 1987), listed 215 sites. The inventory has been upgraded and about 245 thermal prospects are listed in its 1998 version, which is accessible through a VSI website (see bottom of Table 1). We have used the same names, numbering system, and coordinates of the geothermal sites shown in the 1998 VSI catalogue (with the exception of a few not yet given there). A list of 87 Indonesian geothermal prospects already covered by inventory/reconnaissance surveys was also presented by Manalu (1988). Another important registry of Indonesian geothermal prospects is that contained in an unpublished report by Kingston and Morrison (1997), which lists 204 sites and describes their state of exploration.
The selection of Indonesian geothermal prospects for exploration studies was based on earlier reconnaissance surveys. The characteristics of the discharged thermal fluids, types of manifestation, and extent of thermal alteration at the surface, together with geothermometer data derived from chemical analyses, were taken into consideration for the selection. Initially, empirical (liquid and gas) geothermometers were used (Henley et al., 1984); later, theoretical based geothermometers (for example, Giggenbach, 1980, Giggenbach, 1981) were often applied, using selected fluid samples. Between 1970 and 1995, about 70 sites were tentatively classified as high-temperature prospects where geothermometer data indicate deep fluid equilibrium temperatures of >220 °C. Reconnaissance and more detailed exploration studies of most of the 70 prospects are discussed below. Geothermal exploration increased in 1994 when foreign and private investors were encouraged by the Indonesian Government to develop and to run so-called independent power projects (IPPs), which had to sell geothermal power under Energy Sales Contracts to the state electricity company PLN. This resulted in accelerated exploration and production drilling, which came to a halt as a result of a financial crisis in 1997–1998. The history of geothermal exploration in Indonesia between 1970 and 2000 has therefore been divided into three stages: (1) the ‘starting period’, covering 1970–1980; (2) a ‘diverse period’ from 1980 to 1995, and (3) an ‘accelerated development period’ from 1995 to 2000.
Section snippets
The first attempts (1918–1970)
Exploration of geothermal resources associated with active fumarole and solfatara fields with the objective of generating electricity was first proposed in 1918. Initial exploration drilling was undertaken by the Volcanological Section (later to become the Volcanological Survey of Indonesia, or VSI) of the colonial Geological Survey of Indonesia (GSI), at Kawah1 Kamojang, on Java, in 1926.
Geothermal exploration (1970–1980)
During the first PELITA (first 5-year development plan, 1969–1974), the Volcanological Survey group (VSI) completed a geothermal inventory of Sumatra, Sulawesi, and the Halmahera Islands (Radja, 1985, Soetantri, 1986). Geothermal exploration was supported by foreign aid projects. The Indonesian State Oil Company (Pertamina) entered geothermal exploration from 1974 onwards and became responsible for all geothermal exploration in Java and Bali, in line with Presidential Decree PD 16/1974.
The second period (1980–1994): exploration and development on Java
The second period saw a rapid expansion of new and follow-up exploration activities (Ganda et al., 1992). Most of the activity occurred on Java, involving the exploration of roughly 20 prospects (see Fig. 2). For the first time, outflow structures of two prospects were explored by deep drilling. Deep wells were also drilled in six other areas, and four discovered and tested fields were developed by further drilling. Geothermal prospects with significant acid surface manifestations and
Geothermal exploration of Sumatra prospects (1980–1995)
Exploration studies of a few Sumatra prospects conducted during the first half of the 1980s are mentioned by Radja (1985). These led, in 1983, to the drilling of the first deep geothermal exploratory well on Sumatra by VSI in the Lempur–Kerinci prospect, which was sponsored by JICA. The activities of the Pertamina geothermal group began in 1987 with the reconnaissance and exploration of Sumatra prospects. In 1989–1990, a subsidiary of Unocal undertook a follow-up geochemical survey of most
Bali
Exploration of the Bratan Caldera prospect during the 1980s was restricted since parts of the caldera had been given National Park status. However, some additional resistivity surveys (MT) were undertaken by Pertamina in 1987. These were disturbed in part by topographic effects, but allowed penetration of the thick, low-resistivity layer on top. At the beginning of 1994 the fate of the prospect was still uncertain.
High-temperature prospects on Banda Arc Islands (Nusa Tenggara)
Seventeen prospects with significant thermal manifestations occur on Banda Arc
Exploration and development of prospects from 1995 until 2000
The industrial development of explored Indonesian geothermal resources was rather slow prior to 1995. Power plants with a total generating capacity of about 305 MWe had been constructed at Kamojang, Awibengkok, and Darajat. A complex local energy market and inflation made it difficult to secure overseas funding for partial developments. Fixed contracts were introduced from 1994 onwards to allow for development of IPP where steam field development, steam production, and electricity generation
Summary and discussion
About 70 out of more than 200 geothermal prospects throughout Indonesia were identified as potential high-temperature systems before 1995 (Sudarman et al., 2000a) and 42 of these were explored in some detail between 1970 and 2000 using geological mapping as well as geochemical and geophysical surveys (see summary in Table 1, Table 2, Table 3). Another 30 or so areas have only been subject to reconnaissance studies; only half of the sites are mentioned in the literature. Almost all explored
Acknowledgements
During the search of old records and events, important information was provided by Mr. B. Budiardjo, Mr. S. Ganda, Mr. F. Hendrasto, Mr. R. Mulyadi, Ms. P. Utami (the Indonesian team) and Mr. E. Anderson, Mr. I. Bogie, Mr. H. Hole, Mr. E. Layman, Dr. A. Reyes, and Mr. K. Seal. A/Prof. P.R.L. Browne and Dr. J. Moore provided constructive comments to earlier versions of the paper. Ms. L. Cotterall drafted the figures.
References (148)
Geothermal energy potential related to active volcanism in Indonesia
Geothermics
(1986)- et al.
Boiling in low permeability porous materials
Int. J. Heat Mass Transf.
(1982) The Lamongan volcanic field, East Java, Indonesia: physical volcanology, historic activity and hazards
J. Volcanol. Geotherm. Res.
(2000)- et al.
Geochemistry, mineralogy, and chemical modelling of the acid crater lake of Kawah Ijen Volcano, Indonesia
Geochim. Cosmochim. Acta
(1994) - et al.
Geochemistry of the magmatic-hydrothermal system of Kawa Ijen volcano, East Java, Indonesia
J. Volcanol. Geotherm. Res.
(2000) - et al.
The geothermal training centres sponsored by United Nations organisations
Geothermics
(1988) Geothermal gas equilibria
Geochim. Cosmochim. Acta
(1980)Geothermal mineral equilibria
Geochim. Cosmochim. Acta
(1981)- et al.
CO2-rich gases from Lakes Nyos and Monoun, Cameroon; Laacher See, Germany; Dieng, Indonesia, and Mt. Gambier, Australia—variations on a common theme
J. Volcanol. Geotherm. Res.
(1991) Water content of the Kawah Kamojang geothermal reservoir
Geothermics
(1979)
Cenozoic geological and plate tectonic evolution of SE Asia and the SW Pacific: computer-based reconstructions, model and animations
J. Asian Earth Sci.
Assessment and modelling of geothermal reservoirs (small utilization schemes)
Geothermics
Geothermal resources of Sumatra
Geothermics
Volcanism and plate tectonics in the Indonesian Island Arcs
Tectonophysics
Geothermal development in Indonesia
Geothermics
Controls on the Karaha–Telaga Bodas geothermal reservoir, Indonesia
Geothermics
Geothermal energy prospects in South Sulawesi, Indonesia
Development of geothermal resources in Indonesia
The interpretation results of magnetotelluric and Schlumberger resistivity measurement(s) in Lahendong geothermal area, North Sulawesi
Karaha-Telaga Bodas, Indonesia: a partially vapour-dominated geothermal system
GRC Trans.
As plain as the nose on your face: geothermal systems revealed by deep resistivity
Bulls-Eye! simple resistivity imaging to reliably locate the geothermal reservoir
Uncertainty quantification by using stochastic approach in pore volume calculation, Wayang Windu geothermal field, W. Java, Indonesia
Twelve years exploitation history of well Dieng-2, Dieng geothermal field, Indonesia
Plan for the development of the Lahendong geothermal area, North Sulawesi, Indonesia
GRC Trans.
Evaluation of the Dieng geothermal field: review of development strategy
Tectonic framework, resource characterization and development of South Sumatra geothermal prospects
AC effects in resistivity data from geothermal prospects
Resistivity of rocks in geothermal systems: a laboratory study
Reservoir imaging of the Sibayak Geothermal Field, Indonesia, using borehole-to-surface resistivity measurements
Interpretation of fluid pressure measurements in geothermal wells
The Darajat resource: implications for development
Composition of hydrothermal and igneous biotites, and their occurrence in bore hole No.1, Dieng
Geothermal developments in Indonesia: an overview of industry status and future growth
Exploration progress of high enthalpy geothermal prospects in Indonesia
GRC Trans.
Mapping Kamojang reservoir
GRC Trans.
Geology and thermal features of the Sarulla contract area, N Sumatra, Indonesia
Exploration results in the Sarulla Block, North Sumatra
Hululais geothermal scientific review, Bengkulu
Sokoria, East Indonesia: a classic volcano-hosted hydrothermal system
Co-existing volcanism and hydrothermal activity at Kelimutu, Flores Island, Eastern Indonesia
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