Geothermal Energy Development Research Articles

Geodetic imaging of ground deformation and reservoir parameters at the Yangbajing Geothermal Field, Tibet, China

SUMMARYMonitoring and modeling ground surface deformation are crucial for the dynamic assessment of geothermal resources and sustainable exploitation in a geothermal field. In this study, we extract the deformation in the Yangbajing geothermal field by the small baseline-synthetic aperture radar interferometry (SBAS-InSAR) method using 141 Sentinel-1A images collected between March 2017 and November 2021. The InSAR result indicates both uplift and subsidence in the geothermal field. Subsequently, we use a dual-source model combining a dipping ellipsoid and a rectangular surface to model the shallow reservoir that contracted to cause the complex subsidence field in the north of the geothermal field. The shallow reservoir that expanded to cause the uplift in the south is modeled by an ellipsoid source. The parameters inversion is processed by the nonlinear Bayesian inversion method which has been applied to search the optimal parameters setting in a priori space and evaluate the uncertainties by the confidence intervals. To validate our inversion results, we collect the data from 31 wells including extraction and injection wells, detailed tectonic survey data and geothermal isotherms of the Yangbajing geothermal field. The modeled shallow reservoir in the north is within a 140 °C ground isotherm and a 160 °C underground isotherm. The thickness and depth of the reservoir slightly exceed the data from producing wells, probably due to the structural subsidence of the reservoir. The geometric structure is consistent with the channel faults that control the formation and development of the shallow reservoirs. The modeled reservoir under the rebound area in the south is also validated by comparing the data. Furthermore, we estimate the volume loss and recovery of the contracting and expanding reservoirs. We analyse the deformation mechanisms by considering the tectonic formation, the reservoir structure, and the extraction and rechargeability of the reservoirs. This research suggests the deformation pattern of shallow porous reservoirs that have similar layer composition and tectonic structure elsewhere in the world. Moreover, it provides a theoretical model to explore the parameters and volume change of geothermal reservoirs in plateau-embedded basins around the world. Our work is significant for the conservation and development of geothermal energy in geothermal fields that experience deformation, both subsidence and uplift.

Three-dimensional audio magnetotelluric imaging of the Yangyi geothermal field in Tibet, China

The Yangyi geothermal field in southern Tibet has enormous potential for geothermal energy development. It is the high-temperature geothermal field at the highest elevation in the world, and the second largest high-temperature geothermal field in China. The total planned installed capacity of the geothermal power station is 32 MW. At present, no detailed three-dimensional (3D) geophysical survey has been carried out in the Yangyi geothermal field, and in-depth research is urgently needed. The main goal of our geophysical exploration is to study the geothermal structure of this region. In this study, the audio magnetotelluric (AMT) data of 85 stations were collected in the Yangyi geothermal field. The average distance between the stations was about 500 m, and the dimensions of the exploration area were 6 × 7 km. First, we analyzed the magnetotelluric data using the phase tensor method to qualitatively estimate the dimensionality of the subsurface resistivity structure. Then, by performing 3D inversion of 85 AMT data with relatively high quality, the 3D resistivity model from the surface to a depth of 2 km was determined, the high-temperature hydrothermal system under the Yangyi geothermal field was displayed for the first time. In addition, the main characteristics of the geothermal system were identified, and the genetic mechanism of the geothermal system was discussed based on the geological information and borehole data.

Evidence on optimal risk allocation models for Indonesian geothermal projects under PPP contracts

This study explores risk allocation in Indonesia's public-private partnerships for geothermal energy development. Such activity involves significant upfront investment, but no definitive and transparent risk-sharing mechanisms that suitably incentivise the private sector have emerged in the literature. In the study, we develop an evidence-based framework founded on principal-agency theorising that suggests an optimal allocation of risk between the public and private parties in these arrangements. A Delphi survey is employed to identify the views of a group of experts, with the evidence pointing to a clear pattern in identifying high-risk factors and optimal risk-sharing arrangements. Suggested risk-bearing levels for the Indonesian government range between 100% (for legal and regulatory exposures) to 0% in an operational and maintenance risk context. Risks relating to resource and exploration, finance and credit, as well as field development and construction issues, are viewed as being optimally shared between the parties, with the expert panel suggesting that the public sector should retain more exposure where high criticality risk factors exist. The proposed risk allocations reflect both evidenced outcomes and prior contention regarding the risks around geothermal investments and thereby provide the potential for developing meaningful schematics that enable Indonesia to exploit the resources concerned more fully.

Brief Review of the Current Status and Trends in the Development of Geothermal Energy

Brief Review of the Current Status and Trends in the Development of Geothermal Energy

Technology Focus: Drilling Automation and Innovation (February 2023)

With the arrival of the digital age, solutions in big data, automation, and artificial intelligence are rapidly opening the door to a deeper and more-comprehensive understanding of drilling operations around the world. The exponential growth in data acquisition, modeling, and prediction capabilities allows multiple drilling teams to identify hidden patterns and correlations to deal with the most-complicated challenges in well construction. In related SPE papers, it was interesting to read about promising initiatives undertaken by operators, service companies, and academia, not only to recognize details on past drilling events but also to accurately simulate, anticipate, and automate complex situations. Topics such as machine learning for improved decision-making, equipment-failure prediction, well placement lookahead, and autonomous operations have attracted great interest from the industry. Therefore, demand for a skilled workforce in digital technologies will continue to grow in drilling-related disciplines and new information and technology work flows will be incorporated into the well life cycle. As the active rig count continues to increase, safety must remain top priority for drilling operations. Advances in digital technologies and automation contribute to this objective while keeping a focus on cost management, operational consistency, and carbon-footprint reduction. Ongoing actions will also help to accelerate the development of geothermal energy as part of the future mix of renewables. The selected papers highlight some interesting contributions to drive innovation and promote efficient use of processes and technologies. Recommended additional reading at OnePetro: www.onepetro.org. SPE 205899 Measurements During Drilling Through an Innovative Microchip Technology To Determine Accurate Wellbore Properties for Efficient Drilling Operations by Zuyang Zhu, Sinopec, et al. SPE 211791 A Novel Real-Time Well-Collision Avoidance Monitoring by Definitive Dynamic Surveys and Passive Magnetic Ranging by Mahmoud ElGizawy, SLB, et al. SPE 210306 Drilling Heat Maps for Active Temperature Management in Geothermal Wells by Mohamed Shafik Khaled, The University of Texas at Austin, et al.

Tectonics and hydrogeochemical features of geothermal waters in Tangyin Rift SE Taihang Mountain

Geothermal exploration in the Tangyin rift is gaining very important attention due to the increased demand for electricity and space heating in the Hebi City area. Due to geological and tectonic settings of rifting extension, volcanism and a thin lithosphere, it possesses a considerable amount of geothermal potential. Efforts to replace sporadic coal use with clean energy sources like gas, geothermal and electricity have helped reduce air pollutants brought about by many household activities. The present work conducts in-depth structural analysis, geochemistry (major and trace elements), and stable isotope analyses of geothermal waters in an attempt to decipher their hydrogeochemical evolution and their influence on the geothermal potential of Tangyin rift. Correlation analyses are used to determine the geochemical mechanisms that control the geochemistry of geothermal waters. The results indicate that large faults' deformational model, permeability, fluid transportation, and fluid flow direction are influenced by major faults trending NNE-SSW. Furthermore, the waters are classified into five types of hydrogeochemical: Ca-HCO3, Na-Cl–SO4, Ca-Mg-HCO3, Na-HCO3 and Ca-Cl. The Na-Cl-SO4 waters are connected with the Hebi volcano and ascend directly. Subsurface activities including cold water mixing and water-rock interaction have a higher impact on the region's Ca-HCO3 shallow ground waters. The geothermal system is characterized by convection-dominated geothermal play coupled with volcanism, replenished by meteoric fluids flowing through fractures and faults from Taihang Mountain and affected by CO2-rich waters from deeper levels. The reservoir is defined as immature water by the Giggenbach Na-K-Mg triangular diagram and mineral saturation indices (SI) that estimate an average reservoir temperature of 220 °C. Finally, the conceptual hydrogeological model for the Tangyin rift geothermal system was developed which can be used for studying the target for geothermal energy development.

The Potential, utilization, and development of Geothermal Energy in Türkiye

Geothermal energy is a natural resource that can be utilized directly or by converting to other types of energy. Considering the diversity of the geological structure of Türkiye, the geothermal systems have developed depending on young tectonic and volcanic active rock. Western and Central Anatolia are especially rich in geothermal resources. The geothermal well with the hottest well-bottom temperature was drilled in Central Anatolia, and the well-bottom temperature was measured as 341°C at a depth of 3845 meters. In 2022, Türkiye's electricity generation capacity and the total installed direct heat use reached 1663 MWe and 5113 MWt, respectively. Considering Anatolia's Curie depth and heat flux, the probable thickness of the batholith can be regarded as 10 km. For example, the total granitoid area of Western Anatolia is 4221 km2, and at least 2% of this granitoid can provide approximately 8x107 MWh of electricity by Enhanced Deep Geothermal Systems (EDGS). When all granites in Türkiye are considered, it is expected that the future capacity of Türkiye will be much higher with drilling research and development studies and the discovery of new fields. This capacity will exceed 100,000 MWt levels in the medium term, especially with the addition of EDGSs.

A Bayesian multi‐stage modelling framework to evaluate impacts of energy development on wildlife populations: an application to greater sage‐grouse (Centrocercus urophasianus)

Increased demand for domestic production of renewable energy has led to expansion of energy infrastructure across western North America. Much of the western U.S. comprises remote landscapes that are home to a variety of vegetation communities and wildlife species, including the imperiled sagebrush ecosystem and indicator species such as greater sage-grouse (Centrocercus urophasianus). Geothermal sources in particular have potential for continued development across the western U.S. but impacts to greater sage-grouse and other species are unknown. To address this information gap, we describe a novel two-pronged methodology that analyzes impacts of geothermal energy production on pattern and process of greater sage-grouse populations using (a) before-after control-impact (BACI) measures of population growth and lek absence rates and (b) concurrent-to-operation evaluations of demographic rates. Growth and absence rate analyses utilized 14 years of lek survey data collected prior (2005–2011) and concurrent (2012–2018) to geothermal operations at two sites in Nevada, USA. Demographic analyses utilized relocation data, restricted inference to concurrent years, and incorporated 17 additional control sites. Demographic results were applied to >100 potential geothermal sites distributed across the study region to generate spatially explicit predictions of unrealized population-level impacts.•State-space and generalized linear models yield estimates of population growth and lek absence rates, respectively, before and after the onset of geothermal energy production; distances ranging from 2–30 km are evaluated as alternative control-impact footprint hypotheses; this provides inference about the spatial extent as well as the magnitude of impacts associated with geothermal development.•Estimation of important population demographic rates are implemented to investigate the processes by which geothermal energy development might reduce population growth; independent estimates of confounding, environmental effects from 17 control sites are made spatially explicit within ‘impact’ models to establish baseline conditions otherwise masked by collinearity.•Population matrix models are built using estimates from demographic analyses to provide landscape mapping of impacts associated with potential geothermal sites.

Enhancement technology of underground water flow field in coal mine to improve energy efficiency of heat pump system in geothermal energy development

In order to solve the problem that the cold/heat released from the underground pipe of coal mine into the soil layer is difficult to dissipate in a short time, the technology of enhancing the underground flow field of coal mine in geothermal energy development to improve the energy efficiency of the heat pump system is proposed. In this paper, based on the ground source heat pump project located in a coal mine, the energy efficiency enhancement technology of the artificial flow field ground source heat pump system is studied and tested. The test results show that when starting work at about 8:00, due to the increase of heating load, the accumulation of cooling capacity around the buried pipe increases gradually, and the return water temperature at the ground source side decreases gradually. At 14:05, the water was pumped for the operation of the artificial groundwater flow field. It can be seen that the temperature of the return water at the ground source side began to rise gradually, indicating that the accumulation of cold water around the buried pipe was relieved to a certain extent. In conclusion, the artificial groundwater flow field can alleviate the accumulation of cold water around the buried pipe heat exchanger to a certain extent, improve the return water temperature of the buried pipe heat exchanger, and improve the energy efficiency of the ground source heat pump system.

Techno-Economic Investigation of Geothermal Development in Sedimentary Basins

Abstract Models of the enhanced geothermal systems (EGS) in super-hot igneous rocks have demonstrated significantly higher heat transfer rates and power production compared to conventional geothermal systems. On the other hand, along with the high upfront costs, the major geological and technical challenges associated with drilling super-hot EGS wells in igneous rocks constrain the development of geothermal systems and prevent their worldwide application. Meanwhile, geothermal energy development in sedimentary basins could provide clean energy production with relatively lower investment costs compared to super-hot EGS development in igneous rocks. A significant amount of data, knowledge, and expertise has been gathered through decades of drilling and development of oil and gas wells in sedimentary basins. Application of this experience and data for geothermal drilling can eliminate and reduce costs of subsurface data gathering, well drilling, and completion. This paper investigates the economic viability of geothermal energy production systems in sedimentary basins. The study provides initial time-to-hit temperature (THT) and cost-to-hit temperature (CHT) maps across the US based on the well depth, total drilling and completion time, and total well cost data. Combined with sedimentary basin maps and underground temperature maps, THT and CHT maps could be utilized to place EGS wells and other geothermal systems applications at the most favorable locations in the US.

New Advances in Oil, Gas, and Geothermal Reservoirs

The most significant geo-energy sources in the world today continue to be oil, gas, and geothermal reservoirs. To increase oil and gas reserves and production, new theories are constantly being developed in the laboratory and new technologies are being applied in the oilfield. This Special Issue compiles recent research focusing on cutting-edge ideas and technology in oil, gas, and geothermal reservoirs, covering the fields of well drilling, cementing, hydraulic fracturing, improved oil recovery, conformance control, and geothermal energy development.

Current status and issues of development of geothermal and geo-heat energy

Current status and issues of development of geothermal and geo-heat energy

Characteristics And Development Status of Geothermal Resources in Iceland

As Global warming is becoming increasingly severe, decarbonization has become the primary trend in the world. One way to achieve this trend is to use renewable energy resources. Among many kinds of renewable energy, geothermal energy is very neat, and its abundant storage capacity. Also, geothermal resources play a significant role in the energy supply of Iceland. They are utilized both for electricity generation and direct heat application. To this end, this article explains why geothermal energy is abundant in Iceland, and the example of utilization, some advanced technology like drilling technology and power generation technology. In addition, this article introduces the management of geothermal energy like some crucial policies. On this basis, the report concludes Iceland’s experience of a successful transition from using traditional fossil fuels to fully utilizing renewable energy. And the report describes the limitation and future development of geothermal energy.

Numerical Simulation of Geothermal Reservoir Reconstruction and Heat Extraction System Productivity Evaluation

The key to ensuring the economic feasibility of EGS mainly includes two points. On the one hand, it is necessary to ensure the connectivity of the artificial fracture network; on the other hand, it is necessary to determine the most efficient geothermal energy exploitation mode. Most previous studies have only focused on one of the points. To restitute the entire geothermal energy development process, the two parts should be combined to conduct research. In this study, a random fractured medium model was established based on the TOUGH2-BIOT simulation program and the whole process of reservoir stimulation was analyzed. According to the results of reservoir stimulation, different geothermal energy exploitation schemes are set up, and the heat transfer efficiency of the conventional double vertical wells, the horizontal wells, and the double-pipe heat exchange system are comparatively analyzed. The results show that reservoir reconstruction is mainly divided into three stages: In the first stage, the hydraulic aperture of the conducting fractures reaches the maximum value; in the second stage, the non-conductive fractures overcome the in situ stress and become conducting fractures; in the third stage, the rock in the reservoir undergoes shear failure, the fractures expand and connect, and finally, a fracture network is formed. After each stage, the volume of the enhanced permeability area is approximately 10,000, 21,000, and 33,000 m3, respectively. After 30 years of exploitation, the outlet temperature and thermal power output of conventional double vertical wells are the highest, while the horizontal wells have the highest heat extraction ratio. The temperature of a production well in the conventional double vertical wells model, horizontal wells, and double-pipe heat exchange system is 101 °C, 93.4 °C, and 91.6 °C, a decrease of 41.2%, 45.7%, and 46.7%, respectively. The thermal power output is 6.67 MW, 6.31 MW, and 6.1 MW, a decrease of 39.4%, 42.6%, and 44.5%, respectively. The heat extraction ratio of the horizontal wells is 2% higher than the double-pipe heat exchange system and 6.5% higher than the conventional double vertical wells.

Context and mitigation of lost circulation during geothermal drilling in diverse geologic settings

Lost circulation is one of the most common and expensive problems facing geothermal energy development, representing up to 30% of drilling costs. We examined drilling records from four geothermal fields—McGinness Hills in central Nevada, Don A. Campbell and Steamboat Hills in western Nevada, and Puna Geothermal Venture on the Big Island of Hawai'i— to identify geologies most prone to lost circulation, as well as common mitigation strategies. Depths of lost circulation events varied, but their frequency often increased in the production interval. Lost circulation commonly occurred near fault intersections, and heavily faulted fields like McGinness Hills and Don A. Campbell showed secondary mineralization within approximately 100 m (328 ft) or less of where circulation was lost. Lost circulation mitigation strategies included using locally available materials (e.g., cotton seed hulls) as well as more expensive proprietary lost circulation materials, cement plugs above the reservoir, and drilling blind with aerated, polymer-based mud in the production zone. Addressing lost circulation using a well thought out decision-making approach and materials above the reservoir will save time and cost, and provide needed well integrity. Mitigation often requires a series of steps, typically applied from perceived least expensive to most, and are dependent on the severity and location in the well where circulation was lost and availability of materials. Placing cement plugs can cure lost circulation events, however these plugs are often expensive, time-consuming, and may not be successful.

Current Situation, Challenges and Prospects of Geothermal Energy Development in China

Based on the geothermal resource conditions, the current situation of China's geothermal energy utilization in heating (cooling), power generation, hot spring bathing, high-end seed breeding, and hot dry rock exploration and development are explained. The development trend of geothermal energy in the fields of resource discovery, exploration, development and utilization technology, utilization scale, macro policies, and market participants are predicted in the context of the goal of "carbon peak and carbon neutral". Finally, suggestions on the management of China's geothermal industry is proposed.

Numerical simulation of thermo–hydraulic coupling processes in fractured karst geothermal reservoirs

Fractured karst geothermal reservoir is a kind of typical geothermal reservoirs with the advantages of abundant storage water and easy reinjection of tail water during the period of geothermal utilization. Such geothermal system is also one of the geothermal reservoirs with the greatest potential for the development and utilization of geothermal energy in China. However, its geological structures are diverse (e.g. pore, fracture and vug), exhibiting complex characteristics of multiple scales, strong heterogeneity and various flow regimes. Therefore, the fluid-heat transfer processes and geothermal production performance of fractured karst geothermal reservoirs are not clarified. In this paper, a numerical model considering thermo–hydraulic coupling processes based on the discrete fracture–vug network approach is put forward, according to the characteristics of fractured–vuggy geothermal reservoirs. In addition, the accuracy of the numerical model is verified. The results obtained from this research are as follows. First, the numerical model considering the thermo–hydraulic coupling process is put forward, in which the Darcy's law is used to describe the flow zone of porous medium, the Navier–Stokes equation is used to illustrate the free flow zone of vugs, and the Beavers–Joseph–Saffman boundary condition is used to couple the fluid flow between these two zones. Second, the connectivity of fracture network is the key parameter to control and evaluate the flow and heat transfer effects in fractured vuggy geothermal reservoirs. The existence of vugs plays an important role in the fluid flow and heat transfer in geothermal reservoirs. Third, the thermo–hydraulic coupling model based on the discrete fracture–vug network can effectively describe the fluid flow and heat transfer processes in fractured vuggy geothermal reservoirs. The connectivity of fracture networks controls the thermo–hydraulic coupling processes in fractured vuggy geothermal reservoirs. Fourth, the existence of vugs seriously impacts the thermo–hydraulic coupling processes in geothermal reservoirs. For instance, on the one hand, it increases the number of high-speed flow channels spanning across the system and even makes the system get connected. On the other hand, it increases the speed of local flow channels inside the system. In conclusion, this proposed method is of great significance for studying the development characteristics and optimizing their geothermal production performance of fractured vuggy geothermal reservoirs.

Assessment of the Thermal Power of Groundwater Intakes in the Kielce District

Abstract The purpose of the article was to estimate the thermal power of groundwater intakes of the Kielce district within the sheets of hydrogeological maps with the serial numbers MHP 813-817, MHP 850-851, and to indicate in this area prospective areas for the development of low-temperature geothermal energy supported by water/water heat pumps. Based on the calculations on the basis of 147 groundwater intakes, it was determined that the estimated values of thermal power resources are in the range of 3.47 kW to 5757.34 kW. The created map of the low-temperature geothermal potential for groundwater intakes indicates the towns of Bodzentyn, Morawica and the villages of Piekoszów, Wolica and the area around the village of Górno as prospective areas.

The situation analysis of hot dry rock geothermal energy development in China-based on structural equation modeling

In order to combat climate change, China proposed a dual carbon target in 2020. (China's 2030 and 2060 Goals). If the goals can be achieved as scheduled, it will help the world achieve the carbon neutrality goal earlier and improve the increasingly serious global climate. Reducing the utilization of fossil fuels and increasing the share of clean energy in primary energy are major ways to achieve China's 2030 and 2060 Goals. As a geothermal resource with large reserves, high energy storage, clean and pollution-free, dry hot rocks can effectively contribute to the goals. To promote the utilization of dry hot rock, this paper quantitatively studies the factors affecting the development and utilization of dry hot rock, and first summarizes five major influencing factors, namely, resources, environment, market, exploration and development technology, and effective use of technology. Then questionnaire survey based on these five factors was designed and distributed by email to geothermal energy experts in universities (China University of Geosciences, etc.) and research institutions (Chinese Academy of Sciences, etc.). Finally, the questionnaires are subjected to a reliability credibility test and validity analysis to remove the non-conforming items, and the structural equation model was constructed to analyze the data. The results show that environment, market and exploration and development technology have significant effects on dry hot rocks, while resources and effective use of technology have insignificant effects on dry hot rocks. Finally, some suggestions to promote the development of dry hot rocks in China are proposed.

Multi-objective balanced method of optimizing the heat extraction performance for hot dry rock

Geothermal energy, a kind of clean and environmentally friendly energy source, is an important object of future natural resource development and utilization, among which, hot dry rock is one of the important deep geothermal resources. In the current multi-objective optimization of heat extraction performance, reservoir production models are less considered and the effects of different optimization ideas are not compared comprehensively. To improve the heat extraction efficiency and prolong the exploitation life of geothermal reservoirs, this paper determines the appropriate operating parameters of geothermal system (injection temperature, injection rate, production pressure and injection-production well spacing) based on the coupled thermal-hydraulic-mechanical model of hot dry rock exploitation in the Gonghe area of Qinghai and three heat extraction optimization methods. In addition, the heat extraction performances of different schemes are comparatively evaluated. And the following research results are obtained. First, the sensitivity analysis of injection and production parameters shows that power generation and recovery factor are in a reverse relation with injection-production pressure difference, which is the direct reason for the adoption of multi-objective optimization. Second, the optimization scheme prepared on the basis of parametric study indicates that the shortest life of a geothermal reservoir is 10 years, the injection-production pressure difference is up to 67 MPa, there is a significant thermal breakthrough phenomenon and the reservoir safety faces challenges. Third, by virtue of multi-objective optimization and decision making integration, the optimal operation parameter combination of hot dry rock system is determined, the life of geothermal reservoirs can exceed 20 years and balanced optimization is achieved. In conclusion, the idea of multi-objective optimization is feasible and applicable to geothermal energy exploitation and this method provides a reference for the efficient geothermal energy development and utilization and is helpful to the realization of “double carbon” goal in China.