Abstract
Enhanced geothermal system (EGS) is the system for extracting the geothermal heat through the hydraulic fractured reservoir with the circulated fluid. Effective simulating method of the heat extract process is crucial to evaluate the efficiency of the EGS. In order to study the heat extraction process in the complex morphological fractures, the fluid flowing and heat transfer models through the analytical method in multi-link fracture are proposed. The Laplace transform method is applied to simplify the heat transfer equations for both fracture fluid and formation rock. The coordinates transformation is used to study the heat extraction performance in the EGS. The proposed analytical model is compared with the numerical model, which is verified to be efficient. The heat extraction performance of three multi-link fracture cases are simulated. The Case 2 with the longest fracture length has the highest production temperature. The parametric analysis shows that the longer flowing distance is helpful for producing higher fluid temperature and gaining more geothermal heat. The lower velocity and lower fracture width facilitate to obtain higher production temperature. While higher velocity and higher fracture width can extract more geothermal energy. From the above analysis, the multi-link fracture model with analytical method can be applied in EGS simulation.
Similar content being viewed by others
References
Chen J, Jiang F (2015) Designing multi-well layout for enhanced geothermal system to better exploit hot dry rock geothermal energy. Renew Energy 74:37–48. https://doi.org/10.1016/j.renene.2014.07.056
Cheng AHD, Ghassemi A, Detournay E (2001) Integral equation solution of heat extraction from a fracture in hot dry rock. Int J Numer Anal Methods 25(13):1327–1338. https://doi.org/10.1002/nag.182
Dempsey D, Kelkar S, Davatzes N, Hickman S, Moos D (2015) Numerical modeling of injection, stress and permeability enhancement during shear stimulation at the Desert Peak enhanced geothermal system. Int J Rock Mech Min Sci 78:190–206. https://doi.org/10.1016/j.ijrmms.2015.06.003
Ghassemi A, Zhou X (2011) A three-dimensional thermo-poroelastic model for fracture response to injection/extraction in enhanced geothermal systems. Geothermics 40:39–49. https://doi.org/10.1016/j.geothermics.2010.12.001
Ghassemi A, Tarasovs S, Cheng AHD (2005) Integral equation solution of heat extraction-induced thermal stress in enhanced geothermal reservoirs. Int J Numer Anal Methods 29:829–844. https://doi.org/10.1002/nag.440
Ghassemi A, Nygren A, Cheng A (2008) Effects of heat extraction on fracture aperture: a poro–thermoelastic analysis. Geothermics 37:525–539. https://doi.org/10.1016/j.geothermics.2008.06.001
Gringarten AC, Witherspoon PA, Ohnishi Y (1975) Theory of heat extraction from fractured hot dry rock. J Geophys Res 80(8):1120–1124
Huang S (2012) Geothermal energy in China. Nat Clim Change 2:557–560
Jiang F, Luo L, Chen J (2013) A novel three-dimensional transient model for subsurface heat exchange in enhanced geothermal systems. Int Commun Heat Mass 41:57–62. https://doi.org/10.1016/j.icheatmasstransfer.2012.11.003
Jiang F, Chen J, Huang W, Luo L (2014) A three-dimensional transient model for EGS subsurface thermo-hydraulic process. Energy 72:300–310. https://doi.org/10.1016/j.energy.2014.05.038
Lauwerier HA (1955) The transport of heat in an oil layer caused by the injection of hot fluid. Appl Sci Res 5(2–3):145–150
Lu SM (2018) A global review of enhanced geothermal system (EGS). Renew Sustain Energy Rev 81:2902–2921. https://doi.org/10.1016/j.rser.2017.06.097
Mcclure MW, Horne RN (2014) An investigation of stimulation mechanisms in enhanced geothermal systems. Int J Rock Mech Min Sci 72:242–260. https://doi.org/10.1016/j.ijrmms.2014.07.011
Olasolo P, Juárez MC, Morales MP, D´Amico S, Liarte IA (2016) Enhanced geothermal systems (EGS): a review. Renew Sust Energy Rev 56:133–144. https://doi.org/10.1016/j.rser.2015.11.031
Pandey SN, Chaudhuri A, Kelkar S (2017) A coupled thermo-hydro-mechanical modeling of fracture aperture alteration and reservoir deformation during heat extraction from a geothermal reservoir. Geothermics 65:17–31. https://doi.org/10.1016/j.geothermics.2016.08.006
Pruess K (2006) Enhanced geothermal systems (EGS) using CO2 as working fluid—a novel approach for generating renewable energy with simultaneous sequestration of carbon. Geothermics 35:351–367. https://doi.org/10.1016/j.geothermics.2006.08.002
Shi Y, Song X, Wang G, Li J, Geng L, Li X (2019) Numerical study on heat extraction performance of a multilateral-well enhanced geothermal system considering complex hydraulic and natural fractures. Renew Energy 141:950–963. https://doi.org/10.1016/j.renene.2019.03.142
Song X, Shi Y, Li G, Yang R, Wang G, Zheng R, Li J, Lyu Z (2018) Numerical simulation of heat extraction performance in enhanced geothermal system with multilateral wells. Appl Energy 218:325–337. https://doi.org/10.1016/j.apenergy.2018.02.172
Wu B, Xi Z, Jeffrey RG (2014) A model for downhole fluid and rock temperature prediction during circulation. Geothermics 50:202–212. https://doi.org/10.1016/j.geothermics.2013.10.004
Wu B, Zhang X, Jeffrey RG, Bunger AP, Jia S (2016) A simplified model for heat extraction by circulating fluid through a closed-loop multiple-fracture enhanced geothermal system. Appl Energy 183:1664–1681. https://doi.org/10.1016/j.apenergy.2016.09.113
Wu B, Zhang G, Zhang X, Jeffrey RG, Kear J, Zhao T (2017) Semi-analytical model for a geothermal system considering the effect of areal flow between dipole wells on heat extraction. Energy 138:290–305. https://doi.org/10.1016/j.energy.2017.07.043
Wu B, Liu T, Zhang X, Wu B, Jeffrey RG, Bunger AP (2018) A transient analytical model for predicting wellbore/reservoir temperature and stresses during drilling with fluid circulation. Energies 42(11):1–18. https://doi.org/10.3390/en11010042
Zhu J, Hu K, Lu X, Huang X, Liu K, Wu X (2015) A review of geothermal energy resources, development, and applications in China: current status and prospects. Energy 93:466–483. https://doi.org/10.1016/j.energy.2015.08.098
Zimmerman RW, Bodvarsson GS (1996) Hydraulic conductivity of rock fracture. Transp Porous Med 23(1):1–30
Acknowledegements
This work was supported by the National Natural Science Foundation of China (Grant No. 41874216), the Young Elite Scientists Sponsorship Program by CAST (Grant No. 2017QNRC001), and the Program of Introducing Talents of Discipline to Chinese Universities (111 Plan) (Grant No. D18016).
Author information
Authors and Affiliations
Corresponding author
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
Tang, Y., Ma, T., Chen, P. et al. An analytical model for heat extraction through multi-link fractures of the enhanced geothermal system. Geomech. Geophys. Geo-energ. Geo-resour. 6, 1 (2020). https://doi.org/10.1007/s40948-019-00123-2
Received:
Accepted:
Published:
DOI: https://doi.org/10.1007/s40948-019-00123-2