Ulumbu geothermal working area (GWA) is in Ruteng district, East Nusa Tenggara province, Indonesia. Ulumbu GWA is owned by PLN. There are four geothermal power plants (GPP) in Ulumbu, which capacity 4 x 2.5 MW. It has...
Ulumbu geothermal working area (GWA) is in Ruteng district, East Nusa Tenggara province, Indonesia. Ulumbu GWA is owned by PLN. There are four geothermal power plants (GPP) in Ulumbu, which capacity 4 x 2.5 MW. It has operated since 2013. Steam used to generate electricity comes from ULB-2 production well. Wellhead temperature and pressure were 180-200°C and 11 bar. Ulumbu GPP Unit 4 uses a condensing type turbine. It has specific steam consumption (SSC) during commissioning around 9.8 T/MW. After 6 (six) years of operation, SSC becomes 10.04 T/MW on average. It gives a chance to perform optimization in the GPP's equipment. Before performing optimization, evaluation for every equipment based on as-built data is done by modeling using EES software. The method of evaluation is performed by thermodynamics analysis in each GPP's equipment. EES is chosen due to its simplicity to arrange many equations in a single window. EES could communicatively display calculation results through a parametric table, solution window, and diagram window. Operation data give information that turbine inlet pressure is operated under its specification. Turbine inlet pressure is operated under its specification because of the change of operating wellhead pressure. Non-Condensable Gas (NCG) content also decreases based on the last ULB-2 well fluid sampling. Using EES, parameter changes in turbine inlet pressure and NCG content are simulated to get optimum power generation value. The simulation results indicate that optimum turbine inlet pressure is obtained at 9.3 bar with SSC 9.17 T/MW. Ulumbu GPP Unit 4 that operated in that condition could reach cycle efficiency of about 10.39%.
Well casing and cement temperature can change during geothermal production operation. The change of temperature occurs because of the heat transfer from the geothermal fluid to the formation. The heat transfer occurs ...
Well casing and cement temperature can change during geothermal production operation. The change of temperature occurs because of the heat transfer from the geothermal fluid to the formation. The heat transfer occurs because of the temperature difference in geothermal fluid and formation. The heat of fluid moves to the casing, cement, and formation through convection and conduction. This research aims to develop the heat transfer model in the steam production well, predict the steam heat loss and its effect on every 100 m well increment, and predict the well casing and cement temperature distribution and their effect on every well segment. The heat transfer model is an analytical calculation model developed to be the base of the calculation of heat loss and a temperature drop of well casing and cement. This model was developed for the calculation of heat loss in steam production well. The model was compared with a simulator to test the suitability. The fluid flow pressure drop and well lithology were considered in this model. The heat loss was very low during the steam production. The heat loss could be higher, along with the formation temperature drop. The material thermal conductivity and the well segment's layer thickness could affect the steam heat transfer in the production well.
The application of volcanostratigraphy has been broadly used on many early stages of geothermal exploration. The method is simple yet powerful to give a preliminary suspicion on geothermal potential before a field sur...
The application of volcanostratigraphy has been broadly used on many early stages of geothermal exploration. The method is simple yet powerful to give a preliminary suspicion on geothermal potential before a field survey. By combining contour analysis in certain scale (1:50,000 and 1:100,000) such as ridge and river pattern with the stratigraphic analysis of volcanic product the volcanostratigraphy units are determined. In this study, the volcanostratigraphy units were assessed using geothermal potential evaluation scheme for a stratovolcano to determine the potential of a geothermal green *** the object of the study, a quarternary stratovolcano of Slamet Volcanic Complex in Central Java region was analyzed. Eight volcanostratigraphic units were determined in Slamet Volcanic Complex area and its surrounding, including six crowns and two hummocks. In addition, the hydrothermal fluid from several manifestations within the Slamet Volcanic Complex area (warm springs) were analysed to characterize the potentials of Slamet Volcanic Complex Region. Based on these determined volcanostratigraphy units,the occurrence of hydrothermal manifestation within the defined volcanostratigraphy units, the result of hydrothermal fluid analysis, and the criteria matching to the potential evaluation scheme for stratovolcano, the Slamet Volcanic Complex was categorized as potentially beneficial to be surveyed in detail. In such system, the volcanostratigraphy method is relatively simple and reliable to be applied since the volcanic evolution sequences data are accessible.
The desk studies are a fundamental preliminary step in any geologic investigation of volcanic regions. These studies are very important approaches used in the reconnaissance survey stage for the exploration of volcani...
The desk studies are a fundamental preliminary step in any geologic investigation of volcanic regions. These studies are very important approaches used in the reconnaissance survey stage for the exploration of volcanic geothermal systems. Volcanostratigraphic study has been done in Talang volcano and nearby regions, where the two topographic maps on the scale of 1:100000 and 1:50000 were utilized by drawing the patterns of drainage, ridges and flows without intersecting these flows. The first scale employed to distinguish eruption product units based on their respective eruptive centers (Crown), as well as a map on 1:50000 scale to find detailed parasitic distributed unit (s) product such as (Hummock). The challenge based on this approach is to distinguish different volcanic products based on their origins without ground truthing. Thus, the correlation with existing published geological map was employed. One volcanic unit were identified (Talang Brigade) which consists of three eruption centers (The Talang Bawah, Talang Batino and Talang Jantan Crowns) and three Hummocks with different ages based on age of eruption. The volcanostatigraphic units, is bounded by a large Talang Brigade caldera with a diameter more than 2 km. 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 Talang volcano as a geothermal potential that deserves further detailed studies before embarking to development phase. For verifying desk work studies, the detailed volcanostratigraphic mapping is recommended to understand the physical- and chemical properties of the volcanic rocks and provide the history of volcanism and validation of the potentially geothermal boundaries.
Some petroleum wells that are no longer productive still have heat in their formation rocks. Those heat can be extracted and utilized by injecting working fluid into the wellbore. The current study's objective was...
Some petroleum wells that are no longer productive still have heat in their formation rocks. Those heat can be extracted and utilized by injecting working fluid into the wellbore. The current study's objective was to create a 2D numerical calculation program for transient flow temperatures inside the well then it was used to calculate the temperature distribution in oil and gas fields in the Arun field and BK Area. The injected fluids were modeled as a double-pipe heat exchanger. Heat transfer processes inside the wellbore were convection in the inner pipe and the annulus and conduction in the pipe walls and rock formations. The computational calculation used a finite difference method. The computation results were then compared with calculations from the literature. After being validated, the program was used to calculate the Arun field and BK Area temperature distributions. This study found that compared with the reference literature, the current results had a similar optimum temperature range of 130°C-160°C but had different profiles shape with an average deviation of 12%. In the Arun fields, simulation results indicated that the field could reach temperatures between 90°C-120°C and was classified as a medium-temperature geothermal source. BK Area could reach optimum temperatures between 50°C-80°C and be classified as the low-temperature geothermal.
Volcanostratigraphy study is used for supporting geothermal exploration on preliminary survey. This study is important to identify volcanic eruption center which shows potential area of geothermal heat source. The pur...
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Pore pressure estimation is crucial in drilling wells for safety purposes also a very effective method for dealing with drilling accidents. Determination of overpressure is the main foundation in the evaluation to min...
Pore pressure estimation is crucial in drilling wells for safety purposes also a very effective method for dealing with drilling accidents. Determination of overpressure is the main foundation in the evaluation to minimize the non-productive time (NPT). Here we present several models to generate pore pressure analysis of well from Jambi Sub-basin, South Sumatera, Indonesia. The model for estimation pore pressure is carried out by 3 methods: Eaton, Yan & Han, and Kan & Swan. Those methods will be compared to gain a more accurate model estimation within the study area. Kan and Swan's model show the best fit for estimation because this method is suitable for the formation of tester like MDT/DST on higher frequency with parameter of C1 = 0.001 and C2 = 0.0003 for Jambi Sub-basin. The velocity data to construct the 3D pore pressure model was also validated with well data using multi-attribute analysis. The multi-attribute analysis used 2 algorithms, namely step-wise regression and probabilistic neural network (PNN). The analysis show that PNN has a better correlation compared to step-wise regression. The analysis shows the overpressure zone depth is ranges from 1700 – 2000m on Gumai Formation with maximum pressure around 6500 psi. The peak of overpressure dominated by Gumai and Talang Akar formation is caused by the loading mechanism because the rate of sedimentation on thick shale sequence is higher than the rate of dewatering on those formations.
mining water is one of the main problems that has a great importance on mine productivity. In mining implementation, it is necessary to study the mining Water (Hydrogeology) system to support a good mine design. The M...
mining water is one of the main problems that has a great importance on mine productivity. In mining implementation, it is necessary to study the mining Water (Hydrogeology) system to support a good mine design. The mining Water drainage system is a method for making work sites in the mining area always dry. Prior to mining, hydrogeological analysis and rainwater management methods are carried out. Calculation of rainfall intensity using Gumbel Probability estimation and water capture area analysis obtained CA-1 Q = 915, 35, m3 / day CA-2 Q = 1149, CA-3 Q = 141116, 01CA-4 Q = 1407.89, the form of rainwater trapping channels in the form of trapezium and pump requirements in each catchment area of 1 (one) pump each.
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