scholarly journals Performance of Multi-Well Exploitation and Reinjection in a Small-Scale Shallow Geothermal Reservoir in Huailai County

2021 ◽  
Vol 9 ◽  
Author(s):  
Wenzhen Yuan ◽  
Dailei Zhang ◽  
Yi Zhang ◽  
Jun Gao ◽  
Tongzhe Liu ◽  
...  
Keyword(s):  
Water Level ◽  
Geothermal Reservoir ◽  
Shallow Aquifer ◽  
Small Scale ◽  
Geothermal System ◽  
Geothermal Reservoirs ◽  
Well Spacing ◽  
Production Temperature ◽  
Thermal Breakthrough ◽  
Production Strategy

The sustainable development of a shallow aquifer geothermal reservoir is strongly affected by the reinjection–production strategy. However, the reinjection–production strategy optimization of a small-scale exploitation unit with tens of meters of well spacing is site specific and has not yet been fulfilled. This study numerically investigates sustainable heat extraction based on various reinjection–production strategies which were conducted in a single-phase aquitard–aquifer geothermal system in Huailai County, Hebei Province, China. The response of the water level and production temperature is mainly discussed. The numerical results show that production without reinjection induces the highest production temperature and also the water level drawdown. Although reinjection in a single doublet well system is conducive to the control of water level drawdown, the introduction of the thermal breakthrough problem causes a decrease in the production temperature. The thermal breakthrough and sustainability of geothermal reservoirs highly depend on the well spacing between the production and reinjection wells, especially for the small-scale field. Therefore, a large well spacing is suggested. A multi-well system facilitates the control of water level drawdown while bringing intensive well interference and thermal breakthrough. Large spacing between the production and reinjection wells is also the basic principle for the design of the multi-well system. A decrease in openhole length leads to an increase in the production temperature and output thermal power. An increase in the production rate affects the thermal breakthrough highly and shortens the lifetime of the geothermal system. Furthermore, the extracted thermal energy is highly affected by the reduction in the reinjection temperature. The results in this study can provide references to achieve sustainable geothermal exploitation in small-scale geothermal reservoirs.

scholarly journals Study on the Mechanism of Water and Heat Transfer in Sandstone Geothermal System: A Case Study of Doublet Well

Lithosphere ◽  
2021 ◽  
Vol 2021 (Special 5) ◽  
Author(s):  
Jian Shen ◽  
Mingtao Chen ◽  
Shengtao Li ◽  
Zhenpeng Cui ◽  
Yilong Yuan ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Low Temperature ◽  
Flow Rate ◽  
Geothermal Energy ◽  
Injection Well ◽  
Geothermal System ◽  
Temperature Expansion ◽  
Well Spacing ◽  
Increased Risk ◽  
Thermal Breakthrough

Abstract The development of sandstone-type geothermal energy is an important part of the development of geothermal resources and has great significance in promoting environmental protection and energy structural transformation. In sandstone geothermal energy development, recharging is the main method to ensure bottom hole pressure. However, the pressure and temperature changes of sandstone reservoirs under recharge conditions have not been extensively studied. It is easy to ignore the hydraulic relationship between the production and the injection wells, which leads to an increased risk of thermal breakthrough. Therefore, a three-dimensional hydrothermal coupling model is established, and simulation studies of different flow rates, well lengths, and well spacings are completed in this paper. Here, we show the numerical simulation results. The low temperature expansion zone and hydrostatic pressure near the injection well increase with increasing flow rate, and the maximum expansion of the low temperature zone is about 350 m. The low temperature expansion area near the injection well has a small relationship with the well spacing, and the increase in hydrostatic pressure is proportional to the well spacing. As the length of the well increases, the increase in hydrostatic pressure near the injection well decreases, indicating that the injected water under the long well section easily enters the reservoir. When no thermal breakthrough occurs and the hydrostatic pressure drops significantly near the production well, it is recommended that the flow rate be controlled at approximately 20–25 L/s, the well spacing should be 600–800 m, and the well length should be greater than 100 m.

scholarly journals Ground Subsidence Response Conditional On Large-Scale Geothermal Exploitation In A Karst Reservoir Area of North China

2022 ◽  
Author(s):  
Yahui Yao ◽  
Xiaofeng Jia ◽  
Shengtao Li ◽  
Qiuxia Zhang ◽  
Jian Song ◽  
...  
Keyword(s):  
Water Level ◽  
Large Scale ◽  
North China ◽  
Water Pressure ◽  
Geothermal Reservoir ◽  
Ground Subsidence ◽  
Water Level Change ◽  
Geothermal Resources ◽  
Geothermal Reservoirs ◽  
Level Change

Abstract Carbonate karst geothermal resources are widely distributed and have large reserves in North China. Nowadays, the scale of exploitation and utilization of the carbonate karst geothermal resources is gradually increasing. In this work, a geothermal exploitation area where the karst geothermal reservoirs are exploited on a large scale, is selected as the study area, and methods including experiment and numerical simulation are used to study the exploitation-induced ground subsidence problems based on the long-term water level monitoring data of the geothermal reservoir. Through analyses of ground subsidence caused by water level change of the geothermal reservoir, the following conclusions were obtained. The water level drawdown of different types of geothermal reservoirs had different effects on ground subsidence. The maximum ground subsidence of the study area caused by the water level decline of the Jx w carbonate geothermal reservoir was only 0.29 mm/a from 1983 to 2019, which is generally insignificant. In contrast, the same water level change of the N m sandstone geothermal reservoir was predicted to cause 8.9 mm/a ground subsidence. To slow down or even prevent the ground subsidence, balanced production and reinjection are required. From the result of this work, the decline of the water level of the Jx w carbonate geothermal reservoir caused by current large-scale geothermal exploitation will not cause serious ground subsidence. However, attention should be paid to the N m sandstone type geothermal reservoirs as their structures are much more sensitive to the water pressure change.

Water Level Control of Small-scale Hydroelectric Power Plant

2002 ◽  
Vol 122 (6) ◽  
pp. 989-994
Author(s):  
Shinichiro Endo ◽  
Masami Konishi ◽  
Hirosuke Imabayashi ◽  
Hayami Sugiyama
Keyword(s):  
Power Plant ◽  
Water Level ◽  
Hydroelectric Power Plant ◽  
Small Scale ◽  
Hydroelectric Power ◽  
Level Control

Detecting Small-Scale Variability of Trace Elements in a Shallow Aquifer

2015 ◽  
Vol 226 (2) ◽  
Author(s):  
Beatrice M. S. Giambastiani ◽  
Nicolò Colombani ◽  
Micòl Mastrocicco
Keyword(s):  
Trace Elements ◽  
Shallow Aquifer ◽  
Small Scale

Revised hydrogeological model of the hydrothermal system Waiwera (New Zealand)

2021 ◽  
Author(s):  
Andreas Grafe ◽  
Thomas Kempka ◽  
Michael Schneider ◽  
Michael Kühn
Keyword(s):  
Water Management ◽  
New Zealand ◽  
Water Level ◽  
Hot Water ◽  
Hydrogeology Journal ◽  
Natural State ◽  
Geothermal System ◽  
Geological Model ◽  
Species Transport ◽  
Study Region

<p>The geothermal hot water reservoir underlying the coastal township of Waiwera, northern Auckland Region, New Zealand, has been commercially utilized since 1863. The reservoir is complex in nature, as it is controlled by several coupled processes, namely flow, heat transfer and species transport. At the base of the aquifer, geothermal water of around 50°C enters. Meanwhile, freshwater percolates from the west and saltwater penetrates from the sea in the east. Understanding of the system’s dynamics is vital, as decades of unregulated, excessive abstraction resulted in the loss of previously artesian conditions. To protect the reservoir and secure the livelihoods of businesses, a Water Management Plan by The Auckland Regional Council was declared in the 1980s [1]. In attempts to describe the complex dynamics of the reservoir system with the goal of supplementing sustainable decision-making, studies in the past decades have brought forth several predictive models [2]. These models ranged from being purely data driven statistical [3] to fully coupled process simulations [1].<br><br>Our objective was to improve upon previous numerical models by introducing an updated geological model, in which the findings of a recently undertaken field campaign were integrated [4]. A static 2D Model was firstly reconstructed and verified to earlier multivariate regression model results. Furthermore, the model was expanded spatially into the third dimension. In difference to previous models, the influence of basic geologic structures and the sea water level onto the geothermal system are accounted for. Notably, the orientation of dipped horizontal layers as well as major regional faults are implemented from updated field data [4]. Additionally, the model now includes the regional topography extracted from a digital elevation model and further combined with the coastal bathymetry. Parameters relating to the hydrogeological properties of the strata along with the thermophysical properties of water with respect to depth were applied. Lastly, the catchment area and water balance of the study region are considered.<br><br>The simulation results provide new insights on the geothermal reservoir’s natural state. Numerical simulations considering coupled fluid flow as well as heat and species transport have been carried out using the in-house TRANSport Simulation Environment [5], which has been previously verified against different density-driven flow benchmarks [1]. The revised geological model improves the agreement between observations and simulations in view of the timely and spatial development of water level, temperature and species concentrations, and thus enables more reliable predictions required for water management planning.<br><br>[1] Kühn M., Stöfen H. (2005):<br>      Hydrogeology Journal, 13, 606–626,<br>      https://doi.org/10.1007/s10040-004-0377-6<br><br>[2] Kühn M., Altmannsberger C. (2016):<br>      Energy Procedia, 97, 403-410,<br>      https://doi.org/10.1016/j.egypro.2016.10.034<br><br>[3] Kühn M., Schöne T. (2017):<br>      Energy Procedia, 125, 571-579,<br>      https://doi.org/10.1016/j.egypro.2017.08.196<br><br>[4] Präg M., Becker I., Hilgers C., Walter T.R., Kühn M. (2020):<br>      Advances in Geosciences, 54, 165-171,<br>      https://doi.org/10.5194/adgeo-54-165-2020<br><br>[5] Kempka T. (2020):<br>      Adv. Geosci., 54, 67–77,<br>      https://doi.org/10.5194/adgeo-54-67-2020</p>

scholarly journals Determining the Recoverable Geothermal Resources Using a Numerical Thermo-Hydraulic Coupled Modeling in Geothermal Reservoirs

2022 ◽  
Vol 9 ◽  
Author(s):  
Yifan Fan ◽  
Shikuan Zhang ◽  
Yonghui Huang ◽  
Zhonghe Pang ◽  
Hongyan Li
Keyword(s):  
Temperature Drop ◽  
Geothermal Field ◽  
Geothermal Reservoir ◽  
Recovery Factor ◽  
Coupled Modeling ◽  
Geothermal Resources ◽  
Geothermal Heating ◽  
Sustainable Exploitation ◽  
Well Spacing ◽  
Recoverable Resources

Recoverable geothermal resources are very important for geothermal development and utilization. Generally, the recovery factor is a measure of available geothermal resources in a geothermal field. However, it has been a pre-determined ratio in practice and sustainable utilization of geothermal resources was not considered in the previous calculation of recoverable resources. In this work, we have attempted to develop a method to calculate recoverable geothermal resources based on a numerical thermo-hydraulic coupled modeling of a geothermal reservoir under exploitation, with an assumption of sustainability. Taking a geothermal reservoir as an example, we demonstrate the effectiveness of the method. The recoverable geothermal resources are 6.85 × 1018 J assuming a lifetime of 100 years in a well doublet pattern for geothermal heating. We further discuss the influence of well spacing on the recoverable resources. It is found that 600 m is the optimal well spacing with maximum extracted energy that conforms to the limit of the pressure drop and no temperature drop in the production well. Under the uniform well distribution pattern for sustainable exploitation, the recovery factor is 26.2%, which is higher than the previous value of 15% when depending only on lithology. The proposed method for calculating the recoverable geothermal resources is instructive for making decisions for sustainable exploitation.

scholarly journals Synthesis of geochemical techniques to identify the origin and multistage evolution of saline water in a complex geothermal system

2019 ◽  
Vol 98 ◽  
pp. 08005 ◽  
Author(s):  
Yinlei Hao ◽  
Zhonghe Pang ◽  
Tianming Huang ◽  
Yanlong Kong ◽  
Jiao Tian ◽  
...  
Keyword(s):  
Early Stage ◽  
Saline Water ◽  
Eastern China ◽  
Sulfide Oxidation ◽  
Geothermal Water ◽  
Shallow Aquifer ◽  
Geothermal System ◽  
Geothermal Systems ◽  
Origin And Evolution ◽  
A Minor

Elucidating brine origin and evolution is a fundamental but not easy task especially for coastal geothermal systems with possible marine constituents and multistage evolution, as subsequently physical, chemical and biological alteration processes may mask the original and early-stage signatures. Here chemical and isotopic characteristics of water (D and 18O) and dissolved constituents (13C, 14C, 11B and 87Sr/86Sr) have been utilized to investigate the source and multistage evolution of the Jimo coastal geothermal system in eastern China, with dramatic differences of geochemical characteristics observed within a 0.2 km2 area. Results show that geothermal water is derived from paleo-meteoric water and has undergone a 3-stages evolution that involves: (1) Dissolution of marine halite and potash salts in the deep reservoir; (2) Water-rock reactions especially cation exchange produces a Cl-Na-Ca type water as deep geothermal water upwells along the fault zone; (3) A minor (<0.3%) addition of fossil seawater to the shallow aquifer that produces Cl-Na type waters in the west, whereas sulfide oxidation and dissolution of aluminosilicate and carbonates in the east produces Cl-Na-Ca type waters. The methodology utilized in this study offers a means of examining other similar complex geochemical systems having a multistage evolution.

scholarly journals Numerical modelling of the cooling effect in geothermal reservoirs induced by injection of CO2 and cooled geothermal water

2020 ◽  
Vol 75 ◽  
pp. 15
Author(s):  
Hejuan Liu ◽  
Qi Li ◽  
Yang Gou ◽  
Liwei Zhang ◽  
Wentao Feng ◽  
...  
Keyword(s):  
Injection Pressure ◽  
Geothermal Water ◽  
Geothermal Reservoir ◽  
Cooling Effect ◽  
Reservoir Pressure ◽  
Temperature Decrease ◽  
Water Production ◽  
Production Well ◽  
Production Wells ◽  
Thermal Breakthrough

The utilization of geothermal energy can reduce CO2 emissions into the atmosphere. The reinjection of cooled return water from a geothermal field by a closed loop system is an important strategy for maintaining the reservoir pressure and prolonging the depletion of the geothermal reservoir by avoiding problems, e.g., water level drawdown, ground subsidence, and thermal pollution. However, the drawdown of water injectivity affected by physical and chemical clogging may occur in sandstone aquifers, and the reservoir temperature may be strongly affected by the reinjection of large amounts of cooled geothermal water, thus resulting in early thermal breakthrough at production wells and a decrease in production efficiency. In addition to the injection of cooled geothermal water, the injection of CO2 can be used to maintain the reservoir pressure and increase the injectivity of the reservoir by enhancing water–rock interactions. However, the thermal breakthrough and cooling effect of the geothermal reservoir may become complex when both CO2 and cooled geothermal water are injected into aquifers. In this paper, a simplified small-scale multilayered geological model is established based on a low-medium geothermal reservoir in Binhai district, Tianjin. The ECO2N module of the TOUGH2MP simulator is used to numerically simulate temperature and pressure responses in the geothermal reservoir while considering different treatment strategies (e.g., injection rates, temperatures, well locations, etc.). The simulation results show that a high injection pressure of CO2 greatly shortens the CO2 and thermal breakthrough at the production well. A much lower CO2 injection pressure is helpful for prolonging hot water production by maintaining the reservoir pressure and eliminating the cooling effect surrounding the production wells. Both pilot-scale and commercial-scale cooled water reinjection rates are considered. When the water production rate is low (2 kg/s), the temperature decrease at the production well is negligible at a distance of 500 m between two wells. However, when both the production and reinjection rates of cooled return water are increased to 100 m3/h, the temperature decrease in the production well exceeds 10 °C after 50 years of operation.

Sludge thickening performance of mesh filtration process

2004 ◽  
Vol 50 (8) ◽  
pp. 125-133 ◽  
Author(s):  
M.-S. Park ◽  
Y. Kiso ◽  
Y.-J. Jung ◽  
M. Simase ◽  
W.H. Wang ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Water Level ◽  
Domestic Wastewater ◽  
Small Scale ◽  
Mechanical Equipment ◽  
Hydraulic Pressure ◽  
Sludge Treatment ◽  
Filtration System ◽  
Treatment Facilities ◽  
Sludge Thickening

Small-scale wastewater treatment facilities play an important role in improving the aquatic environment in many countries. Although sludge treatment is essential for overall wastewater treatment, it is difficult for small-scale facilities to use mechanical equipment or other facilities. As the first step of the sludge treatment, it is important to develop a convenient sludge thickening process for small-scale facilities. In this work, we examined the sludge thickening performance of a mesh filtration system: the mesh opening sizes of 100-500 μm, and the sludge (3,000-9,000 mg-SS/L) was obtained from a domestic wastewater treatment facility. The filtration was carried out only under the hydraulic pressure between the water level and the effluent port connected to the mesh filter module. The sludge reduction rates were in the range of 85-95% for 6-7 h; the initial filtration rate was very high, but the rate decreased with a decrease in hydraulic pressure due to the reduction of the water level in the vessel. In addition, the effluents (passed through the mesh) contained very low SS and could be directly discharged into the environment.

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