气候变化领域集成服务门户(CCPortal): Elastic and Thermoelastic Effects on Thermal Water Convection in Fracture Zones

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DOI	10.1029/2020JB020940
	Elastic and Thermoelastic Effects on Thermal Water Convection in Fracture Zones
	Patterson J.W.; Driesner T.
发表日期	2021
ISSN	21699313
卷号	126 期号:2
英文摘要	Natural groundwater convection in fractures is an important mechanism of mass and heat transfer in the subsurface, locally altering temperature by several tens of degrees. The thermoelastic stresses resulting from these thermal anomalies induce thermal strains, which in turn alter the transmissivity (permeability times thickness) of the fracture and, therefore, the convective flow within. We investigate the effect of thermal strains on fracture convection patterns using a three-dimensional thermo-hydraulic-mechanical numerical model, implementing the Barton-Bandis relationship between fracture transmissivity and effective normal stress, which results in a downward-narrowing of the fractures. When thermoelasticity is not taken into account, convection forms narrow upflow zones and wide downflow zones. Decreasing fracture stiffness results in similar upflow/downflow patterns, but restricted to the shallow portions of the fracture, creating relatively minor thermal changes. When thermo-elasticity is included in the model, thermal strains induced by cool downflow zones create narrow high-transmissivity channels within the fracture, allowing convective flow to reach greater depths and significantly reducing the geothermal gradient near the fracture. Fracture stiffness is a key parameter in determining convection depth and thermal perturbation strength for a given set of host rock mechanical properties. When fracture stiffness is below some threshold, subsequent contractive thermoelastic strains were found to induce tensile failure of the host rock below the fracture, propagating and deepening the fracture into the host rock. This observation provides support to the previously proposed concept of convective downward migration. © 2020. American Geophysical Union. All Rights Reserved.
英文关键词	convection; fracture flow; fracture propagation; geomechanics; thermomechanics; THM
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/187373
作者单位	Department of Earth Sciences, ETH Zurich, Zurich, Switzerland
推荐引用方式 GB/T 7714	Patterson J.W.,Driesner T.. Elastic and Thermoelastic Effects on Thermal Water Convection in Fracture Zones[J],2021,126(2).
APA	Patterson J.W.,&Driesner T..(2021).Elastic and Thermoelastic Effects on Thermal Water Convection in Fracture Zones.Journal of Geophysical Research: Solid Earth,126(2).
MLA	Patterson J.W.,et al."Elastic and Thermoelastic Effects on Thermal Water Convection in Fracture Zones".Journal of Geophysical Research: Solid Earth 126.2(2021).