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Geothermal wells with a high Non-Condensable Gas (NCG) content still have a certain amount of heat and pressure energy. Geothermal Power Plant (GPP) power generation can be interrupted by high NCG. Energy in high NCG wells can be utilized to reduce house load on GPP to avoid disturbances in the overall GPP system. In this study, the existing condensate pump in the GPP uses an electric motor that supplies power from the house load. This article aims to see the opportunities for utilizing geothermal wells with high NCG as a driver of a backpressure steam turbine. The back-pressure steam turbine will couple to the condensate pump that must inject the condensate into the injection well. The research methodology is collecting actual data from geothermal wells and condensate pump in the GPP. The analysis of data will focus on thermodynamics from the well to drive the condensate pump by using steam turbine backpressure. The result of the study is that the steam flow rate needed to drive the condensate pump in the maximum condition is about 3.31 kg/s, and the actual steam flow rate from a high NCG well is about 4.53 kg/s. It indicates that the geothermal well can drive the condensate pump. It can reduce the house load of GPP to about 138.79 kW per hour or about 1215 MW per year. [ABSTRACT FROM AUTHOR]

Generally, geothermal fields in Indonesia are situated in the mountains, forests, and remote area. The surface area, access, environment, license, and permit are limited, so that from a permitted well pad many wells are designed directionally to reach the reservoir. Directional drilling in geothermal wells is challenging due to hard volcanic rocks, the presence of vugs or cavern, and high temperatures leading to massive lost circulation, drilling break, and the difficulty to turn and control the direction stably during drilling. These cause a critical condition reducing the wellbore quality: high Dogleg Severity (DLS), tight hole, and stuck pipe occurrence. Besides, this leads to higher stress and strain experienced by the casing or liner and causes yield strength reduction and failure. Thus, it is essential that the directional drilling design and operation, particularly trajectory, be optimized. This research summarized methods to evaluate the actual drilling operation and wellbore condition of wells in Dieng Field. The result is useful to identify the critical conditions caused by drilling and formation problems setting the maximum load limitations of the design and subsequent operation. It is recommended that buckling analysis, full-scale testing, and several design and operation scenarios be conducted prior to the drilling operation. [ABSTRACT FROM AUTHOR]

The integrity of perforated liners is crucial in geothermal production wells and this should be well designed according to correct standards. The available geothermal standards, such as the New Zealand Standard, NZS2403:2015, provides a general but less detailed discussion of geothermal perforated liner system design considerations. This research aimed to improve the limitations of NZS2403:2015 by calculating and evaluating the dynamic loads of perforated liner during four phases: borehole drilling and liner installation, flow testing, stand-alone production, and production during the injection operation. The data from production well HCE29 and injection well HCE29A, Dieng Field, Indonesia, were used in this research. In every phase, perforated liner yield strength changed, and load mechanisms varied between 1.3-2.7 and 1.6–4.6 times of the actual liner burst and collapse strength, respectively, and these lead to perforated liner failure and its lifetime reduction. The calculation results, combined with the significant production decline and production casing failure, indicated the perforated liner failure. The results also showed when it was mandatory to revise operation at later phases and to conduct appropriate maintenance according to actual perforated liner condition. Furthermore, this study can be used as a basis of future wells design and operation related to perforated liner. [ABSTRACT FROM AUTHOR]

Casing or liner is one of well integrity components in a geothermal injection well. Various dynamic loads work on casing/liner, including internal loads such as wellbore condition (e.g., dogleg severity/DLS, lost circulation) and external loads such as lithology and impact from nearby wells (production and injection). The internal and external loads influence each other and should be calculated precisely, iteratively, and continuously for casing/liner design during the lifetime of the well. Theoretically, there are many guidelines for loads calculation, such as the New Zealand Standard (NZS 2403:2015). Unfortunately, they are very general and cannot be directly applied in field cases, particularly in Indonesia, thus calculation improvement is required. This study focused on the evaluation of lower liner in a geothermal injection well HCE5A in vapor dominated reservoir with temperature up to 285 °C in Dieng Field, operated by PT Geo Dipa Energi, Indonesia. The loads experienced by lower injection liner were re-constructed and re-calculated. The maximum loads in each phase of operations were considered in the re-calculation. The result showed that failure occurred at lower injection liner. Besides, the methodology developed in this study is used as a standard operating procedure (SOP) for next injection well construction in Dieng Field. • Loads re-construction and re-calculation of the injection liner. • Evaluation of high temperature, DLS, and lost circulation effect on loads. • Corrosion rates simulation and evaluation of the injection liner. • Evaluation and calculation of the actual yield strength rating of the injection liner. • Injection rates evaluation based on the actual yield strength of the injection liner. [ABSTRACT FROM AUTHOR]

• Series of soil gasses measurements (222Rn, CO 2 and δ13C) had been performed in Wayang Windu geothermal field, Indonesisa to infer permeability of fault structures. • High and anomaly of soil gasses concentration (222Rn and CO 2) were correlated with several segments of fault structures. • The δ13C values showed mixtures of soil CO 2 origin, i.e., atmospheric, biogenic and magmatic components. • Transport of 222Rn to surface does not depend on CO 2 as gas carrier. As a geogenic gas, 222Rn (radon) has been widely utilized to infer permeability zones in some geological settings such as fault zones, volcanic and geothermal areas. In this study, soil 222Rn was measured in Wayang Windu geothermal area to infer the relation between fault and permeability. In addition, measurement of soil CO 2 and its δ13C composition were also performed to infer transport mechanism and the origin of soil CO 2. The high and anomaly soil 222Rn, i.e., above 8,500 Bq/m3, were found in the south - southwest area and related to Pejaten Fault, Banjarsari Fault and Cibitung Fault. In contrast, low soil 222Rn was found in the northern area, where several highly productive geothermal wells are located. The high and anomaly soil CO 2 concentrations were also found in a relatively similar area with high 222Rn, but not closely related to the fault structures. Furthermore, the δ13C composition showed that the origin of soil CO 2 in the area was magmatic, biogenic and atmospheric. Based on the 222Rn/CO 2 values and its δ13C compositions, the mechanism of 222Rn transport was interpreted as independent from CO 2 as carrier gas. [ABSTRACT FROM AUTHOR]

Integrity issues create challenges for maintaining the production of mature geothermal wells. Such problems are likely to occur in wells designed according to oil and gas standards, without considering the extreme geothermal environment. PT Geo Dipa Energi as the operator of the Dieng geothermal field, one of the longest operated in Indonesia, has experienced this difficulty since acquiring the field. Almost half of the production wells have been abandoned because of casing issues. To increase production, the operator plans to reactivate wells that have been previously abandoned. An initial study was performed to assess the technical feasibility of reactivating wells at Dieng; it included the development of a well assessment methodology including casing design, comprising historical data analysis, identification of well problems, and investigation of well integrity. The study focused on the identification and characterization of two abandoned wells, HCE9B and HCE28B, current casing conditions, limitations, and challenges to perform a well intervention and workover which is realistic, measurable, economic, and technically feasible. The result of this study will be applicable for casing design for future wells. [ABSTRACT FROM AUTHOR]