Application of Water Fracturing in Geothermal Energy Mining: Insights from Experimental Investigations

Lei, Zhihong; Zhang, Yanjun; Hu, Zhongjun; Li, Liangzhen; Zhang, Senqi; Fu, Lei; Yue, Gaofan

doi:10.3390/en12112138

Cited by 11 publications

(6 citation statements)

References 30 publications

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“…Hence, adequate mathematical model of nonisothermal radial inflow and the produced well gaseous mixture has been developed involving adiabatic and nonadiabatic nature of processes within a formation area, dynamic coefficients of extension, heat conductivity, and thermal diffusion. Further research is topical in the field of the intensified production of geothermal resources from the depleted oil and gas deposits where it is possible to apply hydraulic fracturing techniques, physiochemical and bacteriological methods, and processes intended to develop thick deposits of thermal media [18]- [22].…”

Section: Discussionmentioning

confidence: 99%

Modeling of the lifting of a heat transfer agent in a geothermal well of a gas condensate deposit

Fyk¹,

Biletsky²,

Abbood³

et al. 2020

Min. miner. depos.

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Purpose is to develop mathematical model of nonisothermal inflow and lifting of the recovered gaseous mixture (i.e. geothermal fluid) of a well taking into consideration dynamic coefficient of heat transfer and thermal diffusion coefficient; fluid expansion coefficient in terms of nonadiabatic process; effect of average integral environmental temperature on the heat transfer coefficient; changes in molar mass of the fluid during the well operation; and a process of the productive seam cooling during initial development stages (i.e. months-years). Methods of material and energy balance of fluid-heat flows within a productive formation and within a well as well as forecasting of geothermal fluid production; numerical methods of fluid thermal gas dynamics; Runge-Kutta 4 th order method; and Quazi-Newton method to solve nonlinear equations have been applied. Findings. It has been demonstrated that thermal gradient of rocks and thermal carrier-rock heat exchange vary depending upon operation modes of the formation and the well in terms of temperature effect, temperature difference in humidity, viscosity, compressibility, and other rock characteristics determining efficiency of thermal diffusion as well as coefficient of heat exchange between the fluid and rocks. Originality. The specified equations of thermal energy balance in terms of radial filtration and well product lifting have been developed. The equations are more preferable to compare with the current calculation technique, where a coefficient of fluid is expanded in a seam in the context of nonadiabatic process, and consideration of effect of average integral environment temperature of the heat transfer strength (the known methods takes into account geometric mean of the formation temperature). Actual changes in molar mass of the produced geothermal fluid during the whole period of the well operation (i.e. up to 50 years) are involved. Thermal gas dynamic model well inflow-lifting has been improved owing to the consideration of a transient process of the productive formation cooling during the initial stage of the geothermal fluid production (i.e. months-years). Practical implications. The developed mathematical model helps specify calculation of a well yield by 10-15%. To compare with the standard methods, the model makes it possible to perform 20-30% specification of heat output by a gas condensate well in terms of thermobaric intensification of the fluid production as well as in terms of binary techniques of fluidgeoheat generation.

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Section: Discussionmentioning

confidence: 99%

Modeling of the lifting of a heat transfer agent in a geothermal well of a gas condensate deposit

Fyk¹,

Biletsky²,

Abbood³

et al. 2020

Min. miner. depos.

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“…MShale can simulate hydraulic fracture morphology in fractured and cave-dual media reservoirs [23]. The feasibility of using the DFN method of the MShale simulator for EGS fracturing has been proved by many scholars [6,[24][25][26].…”

Section: Hydraulic Fracturing Simulationmentioning

confidence: 99%

“…Hydraulic shear stimulation in naturally fractured formation has been proven to be effective for power generation and has been used widely in EGS projects [5][6][7]. The fracture network is formed through the self-support of staggered natural fractures after fracturing [8,9].…”

Section: Introductionmentioning

confidence: 99%

Geothermal Characteristics and Productivity Potential of a Super-Thick Shallow Granite-Type Enhanced Geothermal System: A Case Study in Wendeng Geothermal Field, China

et al. 2023

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Super-thick shallow granites without a cap layer are widely distributed in the Wendeng geothermal field. To evaluate the field’s productivity potential for an enhanced geothermal system (EGS), we carried out field tests, laboratory tests and numerical simulations in succession. The geothermal characteristics and deep rock mechanical properties were identified based on real geological and core data from the borehole ZK1 in Wendeng geothermal field. Then, a numerical model of reservoir hydraulic fracturing based on a discrete fracture network was established. Thermal extraction simulations were then conducted to assess the long-term productivity of an EGS project based on the fracturing results. Possible well layout patterns and operational parameters were considered. Results indicated that, for naturally fractured formations, large well spacings should be used and reservoirs with overdeveloped natural fractures should not be selected. For the same reservoir, created by stimulation, the production performances of five-spot and triplet-well modes were different. The pressure indicator was more sensitive to the choice of well layout mode than the temperature indicator. The power generation of the five-spot well mode was slightly improved above that of the triplet-well mode. When selecting the target reservoir, the formations with high temperatures, moderate natural fractures, and high in-situ stress shielding are preferable. On this basis, a large volume of fracturing fluids should be injected to stimulate the reservoir, making the reservoir length and width as large as possible. If the desired large-scale reservoir is created, the five-point well mode should be selected.

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“…Therefore, an interactive relationship can be established to evaluate the hydraulic fracturing effect and water fracture development under different water pressures. Moreover, the strength characteristics are required by hydraulic fracturing [4][5][6][7][8][9][10][11], but it is difficult to carry out the test on-site; therefore, there is a certain engineering significance to establish a model for predicting the strength of the rock through the preliminary detection of the failure morphology of the rock so as to delimit the range of water pressure.…”

Section: Introductionmentioning

confidence: 99%

Study on the Relationship between Fracture Morphology and Splitting Strength of Granite Based on Fabric Distribution

Chen

et al. 2021

Geofluids

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Because of the requirement of the mechanical properties of the damaged surrounding granite rock and the existence of the fracture water in hydraulic fracturing engineering, the strength of granite is related to the fabric, and the roughness of the section is also related to the liquid flow rate, a method of roughly determining the strength of the specimen by observing the failure mode of rock is needed. Considering that the physical and mechanical properties of granite are obviously affected by the fabric, the discrete element numerical simulation method was used to reconstruct the granite fabric based on the spatial correlation function to simulate the splitting experiment to investigate the failure mode of the specimen. The relationship between strength, the fractal value of cross-section, and the fabric was analyzed, which was verified through experiment. The results show that (1) the Voronoi GBM model with spatial correlation function of the discrete element can effectively simulate the controllable granite fabric and carry out micromechanical analysis. (2) The strength of the granite specimen and the fractal value of the cross-section have an obvious linear relationship with the fabric; besides, there is also a certain linear relationship between the strength of the specimen and the fractal value, which is influenced by granite fabric. (3) The predicted strength of the specimen according to the fractal value of the section is in good agreement with the actual strength with the error rate of 30%. In a word, this method can predict the strength of the specimen through the failure section and analyze the hydraulic fracture section and water pressure.

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Application of Water Fracturing in Geothermal Energy Mining: Insights from Experimental Investigations

Cited by 11 publications

References 30 publications

Modeling of the lifting of a heat transfer agent in a geothermal well of a gas condensate deposit

Modeling of the lifting of a heat transfer agent in a geothermal well of a gas condensate deposit

Geothermal Characteristics and Productivity Potential of a Super-Thick Shallow Granite-Type Enhanced Geothermal System: A Case Study in Wendeng Geothermal Field, China

Study on the Relationship between Fracture Morphology and Splitting Strength of Granite Based on Fabric Distribution

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