Well Integrity and Production Management of Acid Reservoir Fluids in Lahendong Geothermal Field, North N orth Sulawesi
Fatah Gunawan, Teguh Prabowo, Sigit Suryanto, Andi J. Nugroho Pertamina Geothermal Energy (
[email protected])
ABSTRACT In geothermal exploration, the benign of the fluid should be considered because it would control the sustainable of not only the well integrity itself, but also the lifetime of production facility which are completely define the steam production. One of the production well in Lahendong has an acid fluids produced from the reservoir with high TDS content, vast mass flow and high reservoir pressure. During operation, the replacement and improvement of wellhead assembly and production facility has been done. Hence, a wide range of study has been conducted in order to determine the source of the acid reservoir fluids and to analyze the current wellbore condition. Due to safety and lifetime operation, the production casing of this has been changed into the smaller size with the specific anti-corrosive material. To maintain the fluid pH, caustic soda is injected at the wellhead and make the fluids flow through production pipe has a pH higher than the original fluids. Keywords: Well Integrity, Production Management, Lahendong, Acid fluid
Conditioning Orifice Application for Steam Flow Measurement at Lahendong Geothermal Field
Yanuaris Dwi Cahyono, Fajar Adi Prasetyo PT. Pertamina Geothermal Energy (
[email protected])
ABSTRACT Flow measurement is vital for both production and reservoir requirement. Orifice has extensively been used for flow measurement device, due to its cheapness, simplicity and the accuracy. Typical standard orifice require certain long distances between orifi ce and major flow disturbances, which mightn’t come in handy in some area. A product so called conditioning orifice by Rosemount offer much shorter pipe length requirement, saving material cost as a result. Both orifice were successfully applied in steam flow measurement during well testing at the Lahendong geothermal field with less than 5% deviation on conditioning orifice compare to standard orifice. This paper analyze the application of conditioning orifice on geothermal steam flow measurement. Keywords: Steam Flow, Standard Orifice, Conditioning orifice, Error, Efisiensi
Case Study of Pressure Drop in One of Steam Pipeline Geothermal Power Plant in West Java
Rizky Akbar, Cukup Mulyana Physic Department FMIPA Unpad (
[email protected])
ABSTRACT The research of steam pressure drop from wellhead to the turbines in the pipelines at geothermal power plant have been conducted. The pipeline, flows the steam from 10 wellheads with 4 clusters along the 3.7 km. Pressure drop is affected by the length of pipe and roughness, elevation, bends and junctions. To calculate the pressure drop as a function of distance , roughness and elevation is used Weymouth equation, while for calculating the pressure drop due to junctions and bends is used modified Bernoulli's equation by adding the head loss due to turbulence effects . The pressure from the wellhead governed by oriffice and used as the initial pressure, and it is varied from 7-10 kg/cm2. In the pipeline there are 1 junction and 28 bends. Assuming the steam velocity in the pipe is 40 m/s , 38 m/s , 37 m/s , 35 m/s and 30 m/s. From the calculation the steam pressure at the header before entering the turbine using T-junction are 6.39 kg/cm2, 6.57 kg/cm2, 6.65 kg/cm2, 6.80 kg/cm2 and 7.16 kg/cm2. If the Y-junctions is used, the pressure in the turbines increase around 0,012 kg/cm2 for 1 junction. Turbine steam pressure design is 6.5 kg/cm2, to get this minimum pressure requirement that compatible with the design, maximum steam velocity should be 38 m/s . Furthermore, from the calculations, the dominant factor that affecting the pressure drop is 90o bend and T-junction. To reduce the magnitude of the pressure drop is suggested that regulate steam velocity around of 38 m/s, replace the T-junction with the Y-junction and replace the 90o bend to 45o bend. Keywords : pressure drop, pipelines, junctions, bends, steam velocity, Geothermal
Prediction of Reservoir Temperature Using Wellbore Simulation on Down-flowed Multiple Feedzone Well
Gamal Hastriansyah, Eric Firanda, Tri Laksana Adi, Marihot S.P. Silaban, Yustin Kamah Pertamina Geothermal Energy (
[email protected])
ABSTRACT In multiple Feedzone well cross flow between between feedzones tended to happen. happen. When shallow feedzone had higher reservoir pressure than deep feedzone, downflow would occur from shallow feedzone to deep feedzone covering wellbore with fluids from shallow feedzone. This caused data from deep feedzone couldn’t be obtained due due to the downflow that masked the deep feedzone. Keywords: multiple feedzone, down-flow, wellbore simulation
Comprehensive Method of Bit Selection on Geothermal Drilling
Ilham Akbar Suhendi, Bonar Tua Halomoan Marbun Institut Teknologi Bandung (
[email protected])
ABSTRACT Geothermal has become a new alternative energies to cover declining conventional fossil energy. Geothermal drilling is more challenging than oil and gas well since the formation is harder and higher in temperature. To drill a geothermal well more efficiently, proper bit selection should be done. Bit selection is one of important considerations of well planning. Suitable bit selection as one of the main tool of drill string can play an important and significant rule in increasing rate of penetration, durability, and consequently reduction of drilling cost. Rock formation hardness directly affecting bit performance. Hardness of igneous or metamorphic rock require a special drilling bit. Higher temperature environment will lead to degradation of bit strength. Conventional bit selection method for oil well cannot be easily adopted. Therefore modification is added to consider temperature, formation hardness, drilling parameter, mud properties, and bit material. Bit records from offset well data become very important in the beginning of bit program. These data provide lithology column, dull bit grading, cost per foot and operational parameter should be compared, examined, and analyzed to the following well. The aim of this study is to optimize bit selection method by considering some special features of geothermal formation. The results gives an accurate bit selection for geothermal drilling with high penetration rate. The results of this study has been validated with a field case in Indonesia. Based on the output, a better method of bit selection and evaluation can be properly designed. Keywords: Bit, Geothermal, Cost per foot
A New Concept of Geomechanics in Geothermal Drilling Design and Operation
Yoga Saktyanto Sisminardi, Bonar Tua Halomoan Marbun Institut Teknologi Bandung (
[email protected])
ABSTRACT Stress field alteration in the geothermal wellbore will be occurred during drilling operation. The contingency of rock stress changes in the geothermal fractured rock reservoir while drilling may lead to situations where the large parts of the fracture network sealed thus causes a reduced heat rate. Uncontrolled wellbore stability factors particularly while drilling, where the permeability is governed primarily by the permeability of the fractures, can have serious destructive effects on the heat extraction rate achievable in reservoirs. The transformation of reservoir permeability can be affected by rock deformation, change in temperature and or pressure around the wellbore, and chemical reaction between drilling fluid and reservoir rock minerals. To avoid geothermal reservoir damage, drilling design and operation must be conducted properly through integrated comprehension of geomechanics. Casing setting depth, hole geometry selection, completion planning, drilling fluid plan, cement plan, casing design, and drillstring design are the important points where the physical properties of the lithology must be properly considered. The other important thing is high temperature reservoir that affects drilling design and operation. The complexity of those parameters must be considered to achieve proper well design, longer well lifetime, and optimized production rate. This study presents a new concept of geomechanics to construct better drilling design and operation in geothermal well. The geologic and geophysics data, reservoir data, production data, drilling data are used to analyze and evaluate the drilling design and operation. Keywords: Geomechanics, Geothermal, Drilling, Operation
Geology and Geochemistry of Geothermal in Torire, Poso Regency, Central Sulawesi Province
Gugy Maulana Firdaus Faculty of Geological Engineering, University of Padjadjaran (
[email protected])
ABSTRACT This research is a study result on geological condition and water geochemistry in Torire, Poso Regency, Central Sulawesi Province. This research evaluating of geological condition and water geochemistry data was carried out over 3 months. This research objects in this study are the geothermal manifestation at surface, water geochemistry, and the relations between its geological condition and water geochemistry. The research results indicate that there are seven hot springs, which can be classified into Bicarbonate hot springs. Reservoir conditions in the study area is estimated associated with sedimentary rocks. Five hot springs in Partial Equilibrium zone and two hot spring in Immature Waters zone. The water drainage pattern in this area is classified as “up flow” drainage pattern having reservoir temperature of between 100-109' Celcius based on calculations of geothermometer. Based on the surface geothermal manifestations, geothermal system at this research area is classified as water dominated system; while based on the reservoir temperature, it is classified as medium enthalpy system. Keywords: Geochemistry, Geology, Hot Water Bicarbonate, Sedimentary Rock, Partial Equilibrium, Immature Waters, Geothermal Systems
Geology and Geochemical Research on Padang Ganting Geothermal Area, West Sumatera Province
Lantip Candraditya, Mochamad Nur Hadi, Arif Rahman Hakim Institut Teknologi Bandung (
[email protected])
ABSTRACT Utilization of geothermal energy for electric power is expected to continue to increase by 9.2 % per year, one of the efforts is to conduct geothermal research using geological and geochemical methods in the area of Padang Ganting, Tanah Datar District, West Sumatra. Geological environment of the research area is in south-eastern of mount Merapi or eastern part of the lake Singkarak. The research area includes on Semangko fault at Singkarak depression segment, in the transition zone between the volcanic arc and the central sumatra basin. Based on geological data, obtained 12 lithology units dominated by Tertiary clastic sedimentary rocks and Pre-Tertiary granite and volcanic rocks such as Quaternary lava and pyroclastic flows, based on the of surface manifestation from 8 manifestation indicate the water type is dissolution water (Sulfate - Bicarbonate), which shows are on the outflow zones associated with hydrothermal volcanic. Geological structures that develop are generally trending on NNE - SSW direction of the Sumatra fault and become a control the appearance of the surface manifestation. Recharge area derived from high topography around mount Merapi and mount Sago that is located in the north of research area. Keywords: Padang Ganting, Geology Geothermal
Saturation Indices of Prograde and Retrogade Solubility Minerals in UBL-11 Fluid During Temperature Drop uf UBL-12 Jodhi P. Giriarso, Hendy Sujarmaitanto, Dradjat B. Hartanto PT. Pertamina Geothermal Energy (
[email protected])
ABSTRACT In period 2012-2013, UBL-12 had experienced cooling because influx of surface water. This event diluted reservoir fluids in cluster D, include UBL-11 as a production well. Dilution effect had seen in the decline of chloride and silica, increase of bicarbonate and sulfate, while NCG decline. WATCH simulation had conducted during this cooling period. Saturation indices of prograde minerals such as amorphous silica, chalcedony, and quartz decreased. Meanwhile, saturation indices of retrograde minerals such calcite and anhydrite relatively increased. This result had not match with the concept of prograde and retrograde solubility minerals. Allegedly, addition of water volume due to dilution caused increase solubility of chloride and silica which led to decrease of the saturation indices, and also increase solubility of water-soluble gases which led to NCG decline. Increase of soluble gases in water led to the rise of bicarbonate and sulfate concentration as precursor of calcite and anhydrite formation. Keywords: minerals, saturation indices, dilution
The Statistical Analysis Comparison between Lip Pressure and Separator in Production Well Testing at Lahendong and Ulubelu Field
Mohamad Husni Mubarok, Yanuaris Dwi Cahyono Pertamina Geothermal Energy/ Institut Teknologi Bandung (
[email protected])
ABSTRACT In order to determine the potential of electrical energy a geothermal well drilled that have been completed, there should be a series of production tests to determine precisely and accurately the characteristics of the geothermal production wells in terms of physical and chemical properties. There are several methods in geothermal well testing, but there are two commonly used methods, lip pressure and separator method. Lip pressure method can be performed in an upright (vertical discharge) or in a flat (horizontal discharge). Basically, both methods have the same purpose, its to clean the drill cutting or mud drilling and to get potential electrical energy that can be generated by these wells. In the progress of the production test, the separator method can present the data characteristics that have more comprehensive than lip pressure. However, separator method need longer preparation, larger cost, more man power and more complicated calculations than the method of lip pressure. From that background, the comparative analysis between the two methods by using statistical tools, in this case used the t-test method. The comparisons were done on eight wells at Lahendong (North Sulawesi) and Ulubele (Lampung) geothermal fields. The comparison was conducted on the rate of vapor and enthalpy for both the production test method. By calculating the error value and the standard deviation at 95% confidence level obtained by the normal distribution curve. Acceptance range for enthalpy of 596 kJ/kg to 1850 kJ/kg and steam rate of 23 tons/hour to 98 tons/hour. In other words, when used the lip pressure method and the results in that range, then we can say it's accurate with a confidence level of 95%. Keywords: Statistical Analysis, Lip Pressure, Well Testing, Lahendong, Geothermal, error number, enthalpy, statistic
Geothermal Binary Power Plant for Lahendong, Indonesia: A German-Indonesian Collaboration Project
Stephanie Frick, Ali Saadat, Gina Andrea Kupfermann, Kemal Erbas , Ernst Huenges International Centre for Geothermal Research at Helmholtz Centre Potsdam GFZ (
[email protected])
ABSTRACT In addition to the use of high-enthalpy geothermal resources in Indonesia, the development of the existing lowenthalpy resources plays an important role for geothermal exploitation. An efficient exploitation of this lower temperature range can significantly extend the exploitable geothermal potential since the plant capacity at many high-enthalpy fields could be increased and low temperature resources can be used for decentralized energy supply. Even though geothermal low temperature power plants offer a huge potential and have been installed at more than 100 sites world-wide, there are still challenges that prevent their application at Indonesian geothermal sites. In order to successfully demonstrate a geothermal binary power plant in Indonesia, a German-Indonesian collaboration project involving GFZ Potsdam (Germany), the Agency for the Assessment and Application of Technology in Indonesia (BPPT) and Pertamina Geothermal Energy (PGE, Indonesia) has been set-up. The demonstration power plant will be located in Lahendong, North Sulawesi, where it uses hot brine from the separator of existing wet-steam production wells. The power plant cycle will be a subcritical, single-stage Organic Rankine Cycle (ORC) with internal heat recovery and an installed capacity of 550 kWe. The on-site integration is aiming at reliability and flexibility so that this technical concept can be easily implemented also at other sites. The scientific work objectives are directed to the systematic analysis and evaluation of all steps in the technical implementation of a binary power plant at an Indonesian site. The knowledge from planning and operating the Lahendong demonstration power plant will serve to define further optimization and development needs and to transfer the gained experience to other possible locations. Extended process understanding and optimum site integration tailored to Indonesian locations is a prerequisite for the expansion and development of binary power plant technology in the future. The presentation will give an overview on the project course and the project goals. Keywords: Binary power plants, Indonesia, Lahendong, Demonstration project
Steam Supply Control Process in PGE Geothermal Operation Fields
Wanda Kurniawan, Nanang Kurniawan PT Pertamina Geothermal Energy e-mail:
[email protected];
[email protected]
ABSTRACT Currently, Pertamina Geothermal Energy (PGE) operates four geothermal fields which are Kamojang (200 MW), Lahendong (60 MW), Sibayak (12 MW) and Ulubelu (110 MW). PGE is also developing several new fields which have been in construction phase. The new fields are Kamojang V (30 MW), Ulubelu III & IV (2x55 MW), Karaha (30 MW) and Lumut Balai (55 MW) Among the fields, Kamojang is the only vapor field where the others are liquid dominated fields. Beside the difference in production fluid, those fields were built at different times; therefore they have different philosophies in design and operation. This paper is intended to compare the process control system used among the fields. The comparison is evaluated not in detail but philosophical aspect.
Applying Chien (1995) Method of Two-Phase Measurement for Geothermal Field Data
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Ali Ashat , Nurita Putri Hardiani , Ryuichi Itoi 1 Geothermal Technology Study Institute Technology Bandung 2 Kyushu University (
[email protected])
ABSTRACT In reservoir modeling, the model calibration through production matching is one of a must-do step before continuing to reservoir performance prediction in the future. In production matching, the data needed is mass flow rate contributed from each individual well. Unfortunately, in water dominated field especially, the measurement of mass flow rate from each well is infrequently conducted. Since it is more common to use central separator for the reason of cost efficiency, the data of the contribution from each well is rare to be found. In fact there are some measurement in two phase flow, e.g., Tracer Flow Test, Lip Pressure, Calorimeter, Coriolis, and Ultrasonic. However, by practice, the measurement with orifice plate is more common. Nonetheless, the orifice plate is only suitable for single phase fluid flow. A notable effort has been done by Murdock in 1962 to enable the two phase flow measurement using orifice plate, but still it was not a very satisfying result in accuracy (deviation of +20% based on the measurement trial in Coso-California). In 1995, the similar approach using orifice plate was conducted by Chien but it has been still more familiar in oil and gas industry rather than in geothermal. Therefore Chien method to measure two-phase flow in geothermal will be verified in this study and applied for real geothermal field data in Indonesia. Keywords: two-phase measurement, Chien method
Simple Resistivity Interpretation from Mt Resistivity Raster Maps Data to Locate Geothermal Reservoir
Maman Somantri Sub. Directorate Geothermal, Directorate of Geological Resources Centre (Retired) (
[email protected])
ABSTRACT Sometimes we can’t do anything with MT resistivity raster maps data to locate geothermal reservoir in a geothermal field area. This paper presents interpretation simple calculation method of MT resistivity raster maps data. The method does not need sophisticated software for analysis but only using spread sheets and common software to locate the geothermal reservoir. It can use old MT measurements, and has given good result data. The method gives a clear image “resistivity profile” target as the geothermal reservoir if the previous survey is wel l designed. Keywords: geothermal, resistivity, MT
Resistivity Structure of Alluvial Geothermal Prospect by Time Domain Electromagnetic Method (TDEM) Survey
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Taruna Fadillah , Budi Sulistijo 1 Master Program of Geophysical Engineering, Faculty of M ining and Petroleum Engineering, Institut Teknologi Bandung, 2 Global Geophysical Group, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung (
[email protected])
ABSTRACT Time-domain electromagnetic (TDEM) surveys were carried out around alluvial region, Sulili district, Pinrang regency, South Sulawesi province, Indonesia at 2013. This study aims to determine the area of low resistivity geophysical data by Time Domain Electromagnetic Method. The surveys were a completion of the previously interpreted geological data collected from geological surveys at 2012. Interpretation of the recorded transient magnetic fields resulted in a general feature of the resistivity structure which are composed of three main layers: a low resistive layer (below 2 Ωm), a medium resistive layer (around 2 -100 Ωm) and a high resistive layer (above 100 Ωm). The low resistive layer is considered to be a complex of altered geological formation. The cros s section of conductance distribution shows region near intrusion and hot water springs have low resistivity characteristic. This evidence indicates that the cap rock of the reservoir near of the geothermal manifestation. Keywords: Alluvial Geothermal Prospect, Time Domain Electromagnetic Methode
Repeated Spontaneous Potential Mappings of Gedongsongo F umarolic Area, Ungaran Volcano, Indonesia
Agus Setyawan Laboratory of Geophysics, Department of Physics, Faculty of Science and Mathematics, Diponegoro University Jl. Prof. Soedarto SH, Tembalang, Semarang, Indonesia, 50275 e-mail:
[email protected]
ABSTRACT The spontaneous-potential (SP) method consists of measuring the potential difference at the ground surface between two points. This passive method allows us to find potential difference anomalies superimposed on regional trends of the potential difference. Gedongsongo area which is located in the Southern part of Ungaran volcano is the main manifestation such as fumarole, hot springs and altered zone. In this paper, we have presented the origin of SP anomalies associated with hydrothermal activity of Ungaran volcano. Time varying SP fields exhibit the dynamic aspect of volcanic activities corresponding to the evolution of hydrothermal activity, with superimposed on local topographyc anomaly and groundwater flow.
Geology and Geothermal Manifestations of Mount Pandan, East Java
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M. Thoha , P. Parman , B. Prastistho , DF. Yudiantoro , I. PermataHati , and IB. Jagranata 1 Students at UPN "Veteran" Yogyakarta 2 Geothermal Study Center of UPN ”Veteran" Yogyakarta (
[email protected])
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ABSTRACT Mount Pandan is a Quaternary volcano formed on Early Pleistocene Epoch (1.2 Ma). It consists of several volcanic eruption centers and geothermal manifestations. This study focused on the northern slopes of Mount Pandan and its surrounding areas which is located in the Klino village, Ngambon district, Nganjuk-Bojonegoro-Madiun borders. The methods used in this study were geological mapping and petr ographic analysis. Volcanic rock units that build this area can be divided into four, namely mount Nangka volcanic rocks unit, mount Telogo Gebang volcanic rocks unit, mount Lawang volcanic rocks unit and mount Pandan volcanic rocks unit. Mount Nangka volcanic rocks are composed by pyroclastic flow breccias, pyroclastic fall breccias, and hornblende andesite lava. Mount Telogo Gebang volcanics rock are composed by lava dome complex of hornblende andesite and pyroxene andesite. The volcanic rocks of mount Lawang consist of andesite lava (volcanic neck) with a columnar and sheeting joint structure. Volcanic rocks of mount Pandan consist of pyroclastic flow breccias, pyroclastic fall breccias and tuff. Mount Pandan area was controlled by Kali Banjar lateral fault, Kali Jati lateral fault, Kali Gandong lateral and reverse fault and Bladogan lateral fault. The Banyu Kuning hot springs was discovered in Kali Pacal, controlled by Kali Banjar fault which has trending N 220° E. Characteristics of this hot springs are T: 38°C, TDS :1295, pH 6-7, and argillic alteration type. At the Jari Kasinan hot spring found on northern Kali Jati fault which has trending N 160°E, characterized by T: 32° C, TDS: 1930-1940, pH 6, travertine calcite and argillic alteration type. The average discharge of hot spring is 1 liter/second and used directly by the local community. Keywords: Mount Pandan, East Java, volcanic rock units, hot spring
Greenfield Exploration of Hidden Magmatically Driven Geothermal Systems in Active Subduction Zones: Case Study Lamongan (Eastern Java, Indonesia)
Fiorenza Deon, Bettina Wiegand, Hans - Jürgen Förster, Inga Moeck, Traugott Scheytt, Makky S. Jaya, Dewi J. Putriatni and Supoyo Helmholtz Centre Potsdam GFZ- International Centre for Geothermal Research Telegrafenberg, Potsdam, Germany
[email protected]
ABSTRACT Magmatic settings involving active volcanism are potential locations for economic geothermal systems due to high temperature and steam pressure. Indonesia, located along active plate margins, hosts numerous areas of active volcanism and, therefore, belongs to the regions with greatest geothermal potential worldwide. However, tropical conditions and steep terrain reduce the spectrum of applicable exploration methods, in particular in remote areas. As an example to conceptualize perspective geothermal systems in those settings, results of a case study from the Lamongan volcanic field in East Java are presented. The study integrates field-based data on the regional structural geology, composition and stable-isotope as radioactive isotopes patterns of thermal waters, and the mineralogy and geochemistry of volcanic rocks. Results indicate infiltration of seawater through faults from the 20 km nearby coast along a NW-SE striking lineament identified by satellite imagery. The possible heat source is geophysically constrained to be quite shallow.
Geochemistry of Thermal Waters from Jarikasinan and Banyukuning Hotsprings, Mount Pandan, East Java
Sutanto, Bambang Prastistho, Jagranatha, Dwi Fitri Yudiantoro, and In tan Paramita Haty Geothermal Research Center UPN Veteran Yogyakarta Jl. SWK 104 Condong Catur, Sleman, Yogyakarta, 55283 e-mail:
[email protected]
ABSTRACT Preliminary research at Mount Pandan found geothermal manifestation. Indication of geothermal in Mount Pandan is characterized by the appearance of geothermal manifestations such as hot springs in the Banyukuning and Jarikasinan.The location of the preliminary research administratively in Nganjuk, Madiun, and Bojonegoro district, East Java Province. The aims of this research is to determine the physical characteristics of hot springs, hot springs chemical properties, and type of the hot springs in the Mount Pandan. The research method is collecting geological data, geochemical data, and laboratory analysis. Based on the field observations there were two hotsprings, Jarikasinan and Banyukuning. Jarikasinan hotspring temperature is 38 ° C - 39 ° C with air temperature 32 ° C, 1930-1940 TDS, pH 6, flow 0.67 L / s and konduktivity of 2.58 ms. Banyukuning hotspring temperature is 38 ° C with an air temperature of 24 ° C, 1295 TDS, pH 6-7, discharge ranged between 1 L/s and konduktivity by 1.92 ms. Keywords: geothermal, geothermal manifestation, geochemical.
Fluid Characteristic in Sibayak Geothermal Field
Hendy Sujarmaitanto, Wahyu Firmansyah Pertamina Geothermal Energy (
[email protected])
ABSTRACT Sibayak Geothermal Field located in the North Sumatra Province of Indonesia. The field belong to PT. Pertamina Geothermal Energy. Volcanism activicty in Sumatra island was generated by a subduction between Eurasian plate and Indo - Australian plate in a shallow depth. This shallow depth of subduction makes the magma product become more acid and more viscous, so that the reservoir in Sumatra most of it found in a sedimentary rock at a shallow depth. Geothermal system generally controlled by regional fault system ca lled “ Great Sumatran Fault”. This dextral strike-slip fault zone accommodate a good secondary permeability and porosity to the geothermal reservoir. Geothermal fluid analysis result show that the anion composition from well XYZ-3 and XYZ-5 in Cl-SO4-HCO3 ternary diagram was plotted near the chloride apex, which indicate the sample was came from a mature chloride reservoir water. Anomaly shown in Na-K-Mg ternary diagram, the plot was located in immature water area and shifting to the potassium because of the high content of potassium. This condition probably because of Sibayak Geothermal Field have a metasedimentary rock reservoir consist of high feldspar and mica or the fluid originally was acid and somehow go through neutralization process. Geothermometer from CAR-HAR and FT-H2S show excess CO2 and H2S with low H2 caused by oxidation process. N2-CO2-Ar ternary diagram explain the fluid from well XYZ -3 & XYZ -5 was a mixture of magmatic gas and gas dissolved in meteoric water. Both of well consist a high concentration of NCG. Keywords: geochemistry, metasediment, neutralization
Improving Microseismic Hypocenter Determination Using Double-Difference Method
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Bambang Mujihardi , Djedi S. Widarto , Andri D. Nugraha , Sri Widiyantoro 1 Upstream Technology Center, PT. Pertamina (persero), Jakarta Indonesia 2 Ph.D. Student, FPS-ITB, Bandung, In donesia 3 Global Geophysical Research Group, FTTM-ITB, Bandung, Indonesia
ABSTRACT This paper describes the hypocenter locations of microseismic events using the double-difference method. An important step in hypocenter determination is how to determine earlier phases of P- and S-wave arrival times at all stations. In this study, we have applied some filtering techniques (band-pass and low-cut filters) to suppress noise. Practically, P waveforms can be determined beforehand based on the earlier phases coming at all stations. Once P-wave arrival times have been obtained, generally S-wave arrival times can be determined subsequently. Here, S-transform analysis has been also applied to improve the picking quality of unclear/bias arrival times. We selected microseismic events with time residuals i.e. the difference between S-wave arrival time (t s) and P-wave arrival time (tp) less than 2 seconds.The next step is the determination of initial locations of microseismic events using the Geiger Adaptive Damping (GAD) method. We then improved/relocated the locations of events by employing the double-difference method. We will present a comparison between hypocenter locations obtained using the GAD and double-difference methods. Some improvements in the locations will be demonstrated.
Preliminary Results of Micro-Earthquake Analysis Around Exploited Hydrothermal Systems in West Java, Indonesia
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Akhmad Fanani Akbar , Riskiray Ryannugroho , Philippe GM Jousset , Alexandra Gassner , Makky S Jaya , Rachmat 1 3 1,2 3 1 2 Sule , Wahyuddin Diningrat , Andri Hendryana , Yosep Kusnadi , Andri Dian Nugraha , Muksin Umar , Yudi 3 1 Indrinanto , Kemal Erbas 1 Faculty of Mining and Petroleum Engineering, Institute Technology of Bandung, Indonesia. 2 GeoForschungsZentrum GFZ Potsdam, Potsdam, Germany. 3 Star Energy, Indonesia. (
[email protected])
ABSTRACT We analyzed micro-earthquake events around exploited hydrothermal regions by deploying dense seismic networks monitoring. We attempt to locate the location of these events in order to enhance our understanding about characteristic of induced micro-earthquake in relationship with hydrothermal activities. In this study we have classified a micro-earthquake which have time difference S-and P-wave phases (ts-tp) less than 3 second otherwise we distinguished as regional or teleseismic events. Then, we picked P-and S-wave arrival times manually. To determine hypocenter locaton, we used geiger’s method. Up to present, we obtained over than 800 micro-earthquakes concentrated around the area study. Future work, we will conduct subsurface seismic velocities through tomography inversion method. Keywords: micro-earthquake, hydrothermal, dense seismic network
Improve Micro-Earthquake Hypocenter using Simulated Annealing and Travel T ime Tomography Inversion in Geothermal Exploration
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Rexha Verdhora Ry Ry , Andri Dian Nugraha 1 Geophysical Engineering, Faculty of Mining and Pet roleum Engineering, Institut Teknologi Bandung 2 Global Geophysical Research Group, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung (
[email protected])
ABSTRACT Observation of micro-earthquake activity in the geothermal exploration is used to detect the fracture and permeability zone. It is necessary for determining the location of precise hypocenter which the process involves finding a hypocenter location that has minimum error between the observed and the calculated travel times. When solving this nonlinear inverse problem, a local optimization technique can easily produce a solution for which minimizes error function, but its function itself depends on initial model and does not necessarily take its global minimum. Other methods such as simulated annealing can be applied to such global optimization problems. Unlike local methods, the convergence of the simulated annealing method is independent of the initial model. Previously, hypocenter location at “RR” Geothermal Field has been determined by Geiger’s method. However, in this study, simulated annealing method was applied on same data and 1-D velocity model to relocate hypocenter and minimize error function. The travel times were calculated using ray tracing shooting method. Our results show hypocenter location has smaller RMS error compared to the previous study that can be statistically associated with better solution. Furthermore, the new hypocenter location data will be used as input to produce 3-D seismic velocity structure for Vp, Vs, and the ratio Vp/Vs by seismic tomography. The travel times on the 3-D velocity model were calculated using ray tracing pseudo-bending method. Inversion method which used for tomography modeling is iterative damped least square. Our tomography inversion results indicate the presence of low Vp/Vs at depths of about 1 – 3 km below MSL. We interpreted this feature may be associated with a steam-saturated rock in the reservoir area of “RR” geothermal field. Another possibility is that the reservoir’s phase system may has changed from water-saturated to steam-saturated. Keywords: micro-earthquakes, seismic tomography, geophysical inversion, ray¬ tracing, Geothermal
Passive Seismic Tomography (PST) Inversion Using Micro Earthquake (MEQ) in DEE Geothermal Field
Mashuri, Bagus Jaya Santosa, Tommy Hendriansyah Institut Teknologi Sepuluh Nopember (
[email protected])
ABSTRACT The development of hydrothermal reservoir characterization has evolved rapidly. Magneto telluric (MT) is a geophysical method which commonly used in geothermal field. One new method that currently use is Passive Seismic Tomography (PST). PST is new technology who introduced by using the concept of ray tracing forward modeling and simultaneous iterative reconstruction technique (SIRT) inverse modeling. PST is used for simultaneous inversion for P and S velocity structures and source coordinates. Tomographic inversion of compressional and shear velocities from field micro earthquake observation at The DEE have been performed by a number of investigators in an attempt to image subsurface structures and important reservoir properties. Anomalies in compressional velocities (Vp), shear velocities (Vs), and the ratio Vp/Vs, have been interpreted to reflect variations in lithology, and pore fluid compressibility within the reservoir. Systematic between Vp and Vs values within the reservoir are found to be incompatible with a simple interpretation based solely on pore fluid compressibility. We take some vertical sections in the MT and PST images result. The result of PST image and MT image has a good correlation. The procedure indicates a combination of the two methods yields good subsurface image in hydrothermal system predictions from micro earthquake and MT data. Keywords: passive seismic tomography, micro earthquake, Vp, Vs
Application of Euler Deconvolution to Characterize Gravity Source Anomalies in Indonesia Geothermal Environment
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Rendy Delliansyah , Rachmat Sule , Andri Dian Nugraha , Yosep Kusnadi 1 Geothermal Engineering, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung 2 Applied Geophysical Research Group, Faculty of Mining and Pet roleum Engineering, Institut Teknologi Bandung 3 Global Geophysical Research Group, Faculty of M ining and Petroleum Engineering, Institut Teknologi Bandung 4 Star Energy Geothermal (WayangWindu) Ltd (
[email protected])
ABSTRACT Double-difference (DD) tomography method was applied to image the P and S-wave velocity (Vp, Vs and Vp/Vs ratio) structures of the geothermal reservoir at ‘RD’ geothermal field in West Java, Indonesia. Data obtained from recording micro-earthquake acquisition recorded by 17 stations for Mei up to July, 2005 and has been successfully identified 353 micro-earthquake events. We first determined the initial location of MEQ events by using Geiger Method with Adaptive Damping (GAD) method and finally only 197 events (1185 P-wave and 1156 S-wave arrival time phases) were selected for the tomography inversion. The initial 1-D velocity structure was determined using VELEST. The model resoslution of the tomographic inversion has been evaluated by checkerboard resolution test. Our tomography inversion model clearly images very low Vp anomaly, low Vs anomaly, and low Vp/Vs ratio value at the elevation of +0.5 km to 1.0 km was interpreted as steam zone that is consistent with the local geological setting. From previous study, we can confirmed that the low Vp/Vs ratio may be related to reservoir zone. The relocated micro-earthquake events were distributed around the reservoir zone. Keywords: : Geothermal, micro-earthquake, double-difference tomography, Vp, Vs, Vp/Vs ratio, reservoir
Delineating Outflow Zones using Linear Features Density (LFD) Derived from Landsat Imageryat Paguyangan, Brebes, Central-Java
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Sachrul Iswahyudi , Asep Saepuloh , Asmoro Widagdo 1 Geological Engineering, Unsoed 2 Faculty of Earth Sciences and Technology, ITB (
[email protected])
1
ABSTRACT Linear features expressed on satellite imagery reflects the geological structuresat surface. Structuresmight serve as permeable zones that fluidscould circulate and generate a geothermal system.Analyzing Linear Features Density (LFD) on spaceborne of Landsat-8 imageryat Paguyangan and surrounding areas provide a preliminary description of an existing geothermal system. Integrated assessment analysis of Landsat imagery and field data are performed in this study. Visual interpretation of linear features on Landsat imagery are conducted based on contrast of tone, hue, and texture. Then, the image is divided into ten grids for area about 30×30 km and contoured based on total length of linear features in everygrid. The field survey data are used to validate the extracted LFD and to interpret the permeable zones related to geothermal system at Paguyangan. Based on field survey and published reference, the Paguyangan areasconsist of threepoints of hot springs location.The hotsprings are located at maximum LFD generally.Therefore, we interpreted that the maximum LFD correspond well to outflow zones of geothermal systems beneath Paguyangan.The high LFD values without geothermal manifestationsout from Paguyangan areaassociated withlocal geological structures. The structures supposed to be out of the fluid path of geothermal system at Paguyangan area. Keywords: Linear Features Density (LFD), hot springs, Paguyangan, Geothermal.
Volcanostratigraphic Study and Its Implication to the Estimation of The Geothermal Resource of Mount Wilis, East Java
Setya Drana Harry Putra, Reza Rizki, Akhmad Fanani Akbar Institut Teknologi Bandung (
[email protected])
ABSTRACT Field mapping and characterization of volcanic regions is one of the methods used in the reconnaissance survey stage for the exploration of volcanic geothermal systems. A difficulty may arise when using this method to distinguish different volcanic products based on their origins directly on the field, because different volcanic eruption centers can produce different eruptive products that look nearly similar both in their physical appearance and characteristics. Volcanostratigraphic study has been done on Mount Wilis region, where we have utilized a topographic map on the scale of 1:100000 to distinguish eruption product units based on their respective eruptive centers (Sub-Khuluk), as well as a 1:50000 map to find detailed distribution of smaller units of eruption products (Gumuk) at the vicinity of Uteran region. It was found that there are at least 4 Sub-Khuluk units, namely Ngebel, Ngargokalangan, Gajahmungkur, and Prau, as well as 5 Gumuk units which are Klotok, Manjutan, Slurup, Patukbanteng, Cemoro, Bandung, and Dangean, that comprise the entire Wilis Mountain volcanic edifice. Based on analyses of the dimension, maturity, stress regimes, and an estimation of the thermal resource base of its magmatic heat source, it was concluded that Wilis Mountain has a geothermal resource potential that deserves further developments. Keywords: Volcanostratigraphic, Geothermal, Resource, Mount Wilis
Tortuosity and Permeability Analysis of Crack Type and Granular Type of Pore Space in a Geothermal Reservoir Rock
Almira Anissofira, Fourier Dzar Eljabbar Latief, Annisa Rachmi Trahwiwit Widijana, Handoyo Universitas Pendidikan Indonesia, Institut Teknologi Bandung (
[email protected])
ABSTRACT Tortuosity is one of a fluid flow property of porous rock which often defined as the ratio of flow path length to the length of the sample. Tortuosity is inversely related to permeability. In this paper we analyze two quantities that describes property of fluid flow inside pore structure of rock, i.e., tortuosity and permeability, of crack-type and granular-type of pore space in a sample of geothermal reservoir rock. Computer simulation of fluid flow through the pore space produces velocity profile of the fluid inside the pore structure. Tortuosity can later be calculated from ratio of the velocity norm to the x-direction of the velocity. Kozeny-Carman relation is used to the measure permeability, by making use of other petrophysical parameters such as porosity, specific surface area, and tortuosity. We obtain tortuosity of crack-type and granular-type which are 1.169861 and 3.196714 respectively. The permeability of the crack-type and the granular-type are 2573.371 mD and 611.9242 mD respectively. From that results, we can conclude that the crack-type of pore space has more significant role in fluid transport compared to the granular-type of pore space. Keywords: Tortuosity, Permeability, Pore Space, Geothermal, Reservoir
Interpretation of Magnetic and Gravity Data to Determine Depth and Area of Reservoir at Rajabasa Lampung
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Haerudin N., , Prasetyo, I. , Sarkowi dan Risdianto, D. 1 Department of Geophysics Engineering, Faculty of Engineering, Lampung University, 2 Badan Geologi Bandung, Bandung, West Java, 40122
[email protected]
ABSTRACT A Model in three dimension will provide the clearer image. It made the interpretation aesier. This study has been carried out to make the 3D modeling for determining area and depth of Rajabasa geothermal reservoir using Mag3D and Grav3D softwareait. The combination of the two geophysical methods that is magnetic and gravity method constructed to reduce reduce ambiguity and increase the accuracy of interpretation. The both Modeling results indicate that the top reservoir is about at 1000 m and the bottom is about at 3500 m depth by mean sea level (MSL) reference. Reservoir area covers the area around Rajabasa Peak, Peak Balerang, Cugung Fumaroles and Pangkul Fumaroles. Results of the both methods are good agreement with the calculated temperature gradient. Keywords: The total magnetic anomalies, Bouguer anomalies, Mag3D modeling, Grav3D modeling, reservoir depth
Structure and Reservoir Modeling Of Bonjol Geothermal Field with Bouguer Anomaly
Ahmad Zaenudin, Rifai Ahmad, and Muh Sarkowi Geophysical Engineering, Engineering Faculty, University of Lampung Jl. Prof. Soemantri Brojonegoro No. 1 Bandar Lampung 35145
email :
[email protected]
ABSTRACT This study aims to map the controller structure and dimensions of the reservoir Bonjol geothermal system. Mapping the structure using Second vertical derivative techniques and reservoir modeling using 3D inversion of the Bouguer anomaly. In general, high-value Bouguer anomaly in the North West and South East and lower section. Fault structures can be delineated with SVD technique and correlated well with the geological structures trending NW and NE. 3D inversion modeling results Bouguer anomaly may indicate that the geothermal reservoir is located in the southern and eastern parts of the study area, with a total density of 1.7 at a depth of 1400 m. While the heat source is located in the Northwest area of research, with a density value of 2.8 gr/cm3 at a depth of 7000 m.
Importance of Distortion Removal in Magnetotelluric (MT) Advanced Data Processing
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Hendra Grandis , Asep Sugianto , Djedi S. WIdarto
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Applied Geophysics Research Group, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung Graduate Program in Geophysical Engineering, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung 3 Pertamina Upstream Technology Center (
[email protected])
ABSTRACT The magnetotelluric (MT) method employs natural electromagnetic (EM) fields to infer the resistivity distribution of the subsurface. The MT technique has a prime role in the geothermal exploration due to its great penetration depth and to a relatively direct relationship between resistivity and temperature properties. However, the MT data exhibit fundamental limitations, i.e. they are deduced from low amplitude signals relative to the noise and suffer from distortion related to subsurface inhomogeneities. The paper demonstrates the effects of distortion of simulated MT data associated with a simple geothermal synthetic model. The importance of the MT impedance tensor decomposition is illustrated by the application of the well-known Groom-Bailey technique to remove the distortion in the synthetic and field data of a geothermal prospect. Keywords: Magnetotelluric, Distortion Removal, Data Processin, Geothermal
Application of Euler Deconvolution to Characterize Gravity Source Anomalies in Indonesia Geothermal Environment
Rocky Martakusumah Institut Teknologi Bandung (
[email protected])
ABSTRACT Gravity surveying in any of Indonesia geothermal prospect is useful to recover intrusive bodies and major faults. Euler deconvolution technique could be applied to gravity data to estimate depth and location of the gravity source anomalies. In details, faults could be interpreted from Euler deconvolution by using structure index (SI) of 0, while intrusive bodies use SI of 1. According to a test conducted in one of Indonesia geothermal prospect, it was revealed that the Euler deconvolution could detect the location and depth of faults and intrusive bodies that has not been recognized at the surface. Keywords: Euler Deconvolution, Gravity, Structure Index
Referral Area Development Based on PLTP (Geothermal Power Plant) from The Ecological Footprint, Microtremor, and GPS Observation. Study Case: Geothermal Potential of Mount Ijen, Bondowoso, East Java
Widya Utama, M. Taufik, SE. Prabawa, P. Ariastita, Belinda Program Studi Teknik Geofisika, Institut Teknologi Sepuluh Nopember (ITS) (
[email protected])
ABSTRACT The existence of PLTP (Geothermal Power Plant) is a form of fulfilling the needs of electrical infrastructure in a region with sustainability concept. PLTP is an opportunity but also a threat in regional development. Thing to consider is the construction of the location of geothermal power plant must be in a safe and appropriate condition. In addition, the presence of PLTP allegedly able to reduce the carrying capacity of the region. A safe location is a location which is safe from disaster and aftermath was not a disaster. Therefore comprehensive study that consists of ecological footprint analysis, microtremor and GPS observation was used in this study. Geothermal potential area studied is in Mount Ijen, Bondo woso, East Java. Based on study’s ecological footprint is known that at this stage the development of geothermal power plan ecological surplus amounted to 24,140. Microtremor studies provide information on the local rock response both tectonic earthquake and volcanic indicated by the value of the natural frequency and low amplification dominant. While GPS observation provide information and large shift towards land vertically and horizontally at the study site. Comprehensive analysis of these three studies of land suitability level information for the development of geothermal power plants that land area are suitable for the development of geothermal power plants by 56 %; quite appropriate at 40 % and amounted to 4 % does not match. Keywords: PLTP, Geothermal, Mount Ijen, Ecological Footprint, Micrometer, GPS
Micro-earthquake Analysis in "Alpha" Geothermal Field: Hypocenter Relocation, Local Magnitude Determination, and Moment Tensor Inversion
Hasbi Ash Shiddiqi, Wiku Widyoyudo, Akhmad Fanani Akbar, Afnimar, Andri Dian Nugraha, Rachmat Sule, Yosep Kusnadi Institut Teknologi Bandung (
[email protected])
ABSTRACT A series of micro-earthquake (MEQ) monitoring were conducted "Alpha” geothermal field in 1998, 2005 and 2007/2008. We have analyzed 474 micro-earthquake data from those monitoring projects. Considering that MEQ hypocenter is an important parameter in seismicity analysis, we conducted hypocenter relocation using highly precision double-difference relocation algorithm. We determined local magnitude of those MEQ in order to assess the safety of seismicity in this field. From magnitudes determination, we found that the range of micro-earthquake magnitudes from this field are from ML -1.4 to ML 2.4 and 85% of those event have local magnitude below ML 1. The local magnitude range of those MEQs indicated that seismicity during MEQ monitoring is too small to be felt on the surface. We also performed full moment tensor inversion to analyze the source mechanism to acquire a better understanding of micro-earthquake source mechanisms in "Alpha" geothermal field. Our inversion result shows that most of those MEQs have more than 50% non-double couple component (compensated linear vector dipoles and volumetric). This result may indicate that those MEQ mechanisms could possibly caused by shear and extensional faulting associated with fluid and steam flow. Keywords: micro-earthquake, geothermal, hypocenter relocation, local magnitude, moment tensor
Structural and Dynamic Assessment of Geothermal Reservoirs from Multiparameter Observations: Example in West Java, Indonesia
Philippe Jousset, Rachmat Sule, Wahyuddin Diningrat, Devy Syahbana, Alexandra Gassner, Sebastien Guichard, Fanani Akbar, Riskiray Ryannugroho, Andri Hendryana, Yosep Kusnadi, Andri Nugraha, Muksin Umar, Makky Jaya, Kemal Erbas and Bambang Pramono International Centre for Geothermal Research at Helmholtz Centre Potsdam GFZ Telegrafenberg, 14473 Potsdam, Germany e-mail
[email protected]
ABSTRACT We assess geothermal resources from our understanding of the structure and the dynamics of geothermal reservoirs and hydrothermal systems in the south of Bandung. The co-existence of a large variety of intense surface manifestations like geysers, hot-steaming grounds, hot water pools, and active volcanoes suggest an intimate coupling between volcanic, tectonic and hydrothermal processes in this area. In order to estimate structural features of this volcanic complex, we deployed a geophysical network around geothermal areas. We started with a network of 30 seismic stations including 26 high-dynamic broadband Güralp and Trillium sensors (0.008 - 100 Hz) and 4 short-period (1 Hz) sensors from October 2012 to December 2013. We extended the network in June 2013 with 18 short-period seismometers. In order to access dynamical features and relate them to the structure, we deployed a geodetic network including a continuously recording gravity meter, a GPS station and tilt-meters. We describe the set -up of the seismic and geodetic networks and we discuss first observat ions and results. Earthquakes locations were estimated using a non-linear algorithm, and revealed at least 3 earthquake clusters. We perform joint inversion of hypo-center and velocity tomography. We discuss the resulting seismic pattern within the area and relate the structure to the distribution of hydrothermal systems. The integration of our observations and interpretations will allow us to achieving a better understanding of structures and the dynamics of those geothermal reservoirs. This approach contributes to the exploration and the sustainable and optimal exploitation of geothermal resources in Indonesia.
Determining Qp, Qs, and Qp/Qs Ratio Structures Using Micro-Earthquake Waveform Data in the “NHA” Geothermal Exploration
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Muhammad Naufal Hafiyyan , Andri Dian Nugraha 1 Study Program of Geophysical Engineering, Faculty of Mining and Petroleum Engineering, Institute of Technology Bandung 2 Global Geophysical Research Group, Faculty of M ining and Petroleum Engineering, Institute of Technology Bandung (
[email protected])
ABSTRACT We conducted attenuation tomography inversion using micro-earthquake data in the “NHA” geothermal exploration field. We analyzed dynamic range of micro-earthquake waveform for determining the operator attenuation (t*) of P-and S-wave to invert for Qp, Qs, and Qp/Qs ratio frequency independent structures (attenuation = Q-1) using spectral fitting and spectral ratio methods. For the attenution tomography inversion, the 3-D seismic velocities result from previous study was used in this study. The results of attenuation in this study show the low Qp/Qs ratio region is observed close to the production well which is consistent with low Vp/Vs ratio from previous study. This phenomenon probably correlated with the existing of steam zone around geothermal reservoir. Keywords : geothermal, micro-earthquake, tomography, attenuation
Tomographic Inversion Using Micro-Earthquake Waveform Data in the “BS” Geothermal Exploration Field
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Billy S Prabowo , Mia Uswatun Hasanah , Rachmat Sule , Andri Dian Nugraha , Yosep Kusnadi 1 Geothermal Engineering, Faculty of Mining and Petroleum Engineering, ITB 2 Near Surface Geophysics Laboratory, Faculty of Mining and Petroleum Engineering, ITB 3 Applied Geophysics Research Group, Faculty of Mining and Petro leum Engineering, ITB 4 Global Geophysical Research Group, Faculty of Mining and Petroleum Engineering, ITB (
[email protected])
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ABSTRACT We analyzed high dynamic range of micro-earthquake waveform data in order to determine t* operator attenuation to invert for Qp and Qs frequency independent tomography. The objective of this study is to delineate fluid and steam saturated zone around “BS” geothermal reservoir zone. We have determined t* of P -and S-wave as input for the Q-tomographic inversion to image Qp and Qs structures around reservoir. During the inversion, we used 3-D seismic velocities structure from the previous study. Our preliminary results show strong low Qp and low Qs values around reservoir zone which may be associated with steam saturated zone. The obtained Q parameters in this study will give additional impormation for much better contstraint in the interpretation of subsurface in geothermal exploration. Keywords: attenuation, tomography, microseismic, geothermal
3-D Shear Wave Splitting Tomography Using Micro-earthquake Data in the Geothermal Field
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Tania Meidiana and Andri Dian Nugraha Master Program of Geophysical Engineering, Faculty of M ining and Petroleum Engineering, Institut Teknologi Bandung, 2 Global Geophysical Group, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung (
[email protected])
ABSTRACT In this study, we developed a three-dimensional shear wave splitting tomography method in order to image subsurface anisotropy distribution in the geothermal field. Shear wave splitting occur when linear shear wave travels through anisotropic medium lead to orthogonal slow and parallel fast shear wave. There are two important parameters which are associated with shear wave splitting event such as the polarization direction and the differential delay time between the arrival of the fast and slow shear wave. Our results show there are three predominant polarization direction groups in geothermal field including 150 - 450 NE, 550 -900 NE, and 1250 1350 NE. The delay time averages for each station has a range between 0.01 - 0.05 s. Anisotropy distribution is indicated by a parameter of anisotropy percentage (K). In this study, we show anisotropy percentage range between 0 - 1 %. Area with high anisotropy percentage is generally located around production wells with variations value in the Vp/Vs ratio. In conjunction with P-wave velocity (Vp), S-wave velocity (Vs), or attenuation structures, development of three-dimensional shear wave splitting method is expected to provide usefull additional information for the geothermal field interpretation. Keywords: Shear wave splitting, polarization direction, delay time ,anisotropy, geothermal.
Introduction A Geothermal Subject Matter to Physic Program Curriculum: Case Study on Surface Manifestation Nanang Dwi Ardi Physics Program, Universitas Pendidikan Indonesia (
[email protected])
Abstract Lack of human resources in geothermal energy development is a challenge for Indonesia. Physics program is one of institution that it should answer the problem. From background analysis, most students in our department did not understand about geothermal, even just in definition. To encourage about geothermal knowledge, we have been conducted an inserted curriculum on geothermal theme, especially in earth physics student class interest. The students will take courses for Geology Geophysics, Geophysics Exploration as a compulsory, but Geothermal Thermodynamics as a supplementary. Although as an elective course, Geothermal Thermodynamics has an important role to enhance a contemporary and coherent understanding of geothermal energy, physics, and their interrelationships, then the course is opened to fifth semester students to fulfill their first concept about geothermal. But, taking the course on that semester still brings a fundamental problem, such as surface manifestation. Then, integrated measure should be taken to get comprehensive understanding about the concept. Geology Geophysics helps the students to understand the system and Exploration Geophysics makes them know well about how to survey it. The effort of this integration is profile from a measurement with resistivitymeter above the surface manifestation. Futhermore, physics students will response the challenge about geothermal lackness in human resources. Keywords: Physics, geothermal curriculum, surface manifestation
Geochemistry Geothermal Area in Sulili, pinrang Regency, South Sulawesi Anna Yushantarti, Sitti Nur Asnin, Dede Iim setiawan Center for Geological Resources and Institut Tecnology Bandung (
[email protected])
Abstract Sulili geothermal area is located in Pinrang regency, South Sulawesi Province. Sulili geothermal area is dominated by northwest-southeast structure which forms depression, part of Walanae structure. The youngest product in Sulili is Trachitic Tirassa which is 0,7 ± 0,2 ma or Pliocen. Sulili has chloride type of waters based on Cl-SO4-HCO3 diagram and plots in partial equilibrium zone based on Na-K-Mg diagram. The temperature of reservoir is about o 210 C from Na-K geothermometry. Keywords: Geothermal, Geochemistry, Suliil, Sulawesi
Preliminary Results of Probabilistic Seismic Hazards Analysis At “DAZ” Geothermal Field 1
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Dicky Ahmad Zaky , Andri Dian Nugraha1 , Rachmat Sule , Yosep Kusnadi 1 Faculty of Mining and Petroleum Engineering, Institute Technology of Bandung, Indonesia. 2 Star Energy, Indonesia. (
[email protected])
Abstract This study is intended to assess possibility of seismic hazard in “DAZ” field using Probabilistic Seismic Hazard Analysis (PSHA) method. The data will be used are recording of seismogram from October 2012 to August 2013. Routine data processing such as event determination, picking arrival time of P and S wave, hypocenter location and magnitude determination will be conducted first before analyzing the Probabilistic Seismic Hazard Analysis (PSHA). Our preliminary results show that most of micro-earthquake hypocenters are occurring at depths of 3 - 4 km. This also could be identified from time difference between arrival time P and S wave, about 1,5 – 2,5 s. Hence, could be known that the earthquakes occurred underneath the reservoir of “DAZ” field. Interesting result, the possible source of micro-earthquake at this depth is the local fault or volcanism activities. The next steps that will be conducted are moment magnitude (Mw) and seismic moment (M0) determinations which will be used in calculate the “b” value and PSHA. The results of PSHA are hazard curve and map which show the probability of seismic hazard. Later, the results are e xpected could give recommendations related to risk of seismic hazard in “DAZ” geothermal field. Key words: PSHA, seismic hazard, moment magnitude, geothermal
The Integrated Geophysical Data Of The Diwak and Derekan Geothermal Hot Springs, Semarang, Central Java, Indonesia Udi Harmoko, Gatot Yulianto, Sugeng Widada, Yusuf D.H., Sahid Geophysics Lab., Faculty of Science and Mathematics, Diponegoro University (
[email protected])
Abstract The Diwak and Derekan hot springs are located at the Bergas Sub district, Semarang Regency, Central Java, Indonesia. Each of the main geothermal activities is used for tourists area proposes. The geology, geochemistry and geophysical explorations have been proposed to improve the geothermal benefits. We present integrated geophysical data to characterize a geothermal system at the hot springs. The resistivity model indicates the hot springs are located in a region of intersecting fault trends associated with direction of river flows, Lutung and Klampok rivers. Magnetic and gravity data characterize this major fault along with other smaller scale structures in the area. A 3D resistivity data indicates that water is upwelling in the fault plane, and suggests that the fault does provide the means for heated water to migrate to the surface. The reserve potential of the geothermal reservoir was estimated to be about 165,63 kWe as calculated by heat loss method. Keywords: Diwak, Derekan, geophysics, potential, heat loss
Preliminary Results of Seismic Anisotropy Analysis Using Micro-Earthquake Waveform Data In “BQ” Geothermal Field, West Java, Indonesia 1
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Bilqis Afifah Amatullah , Andri Dian Nugraha , Rachmat Sule , Yosep Kusnadi 1
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Faculty of Mining and Petroleum Engineering, Institute Technology of Bandung, Indonesia. 2 Star Energy, Indonesia. (
[email protected])
Abstract “BQ” geothermal field is located in West Java, Indonesia. In this study, we used micro -earthquake waveform data to analyze subsurface anisotropy structure around reservoir of the geothermal field through estimating the delay time between S-wave slow and S-wave slow seismic velocity. There are several steps to be conducted including event identification, pick of P-and S-wave arrival times, and micro-earthquake hypocenter determination. Our preliminary results show 51 micro-earthquakes and 13 regional events have been identified from continuos dense seismic network monitoring in the area study. Future work, we will add more micro-earthquake data, determining the events location and finally conducting seismic anisotropy analysis in this geothermal field. Keywords: Micro-earthquake, geothermal, anisotropy
Preliminary Results of Identification of Fluid Saturation Zone Using Seismic Attenuation Tomography from Micro-Earthquake Data in “FF” Geothermal Field 1
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Fadli Faturrahman R , Andri Dian Nugraha , Rachmat Sule , Yosep Kusnadi 1
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Geothermal Engineering, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Indonesia 2 Star Energy, Indonesia (
[email protected])
Abstract Micro-seismic mapping has been proved to be a valuable technology for geothermal reservoir monitoring hydraulic fractures, fluid saturation zone and other reservoir processes. Seismic attenuation tomography is one of the method that can be used to determine fluid saturation zone. This method use attenuation values (Qp, Qs and Qp/Qs ratio) and then compare the result with velocity profiles (Vp, Vs and Vp/Vs ratio) to determine the fluid saturation zone. Result of previous attenuation tomography study successfully showed the pressence of fluid saturation zone. In this study, we expect to get the same result using micro-earthquake data from dense seismic network monitoring. Futhermore, we also want to see changes in the distribution of fluid saturation zone from 2007. These result are expected to help the strategy for increasing the capacity of power plant. Keywords: micro-earthquake, attenuation tomography, fluid saturation
