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Flow to a heated borehole in porous, thermoelastic rock: Analysis
Author(s) -
McTigue D. F.
Publication year - 1990
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/wr026i008p01763
Subject(s) - borehole , thermoelastic damping , permeability (electromagnetism) , thermal diffusivity , heat flux , fluid dynamics , porosity , mechanics , porous medium , flux (metallurgy) , geology , thermodynamics , materials science , heat transfer , geotechnical engineering , thermal , physics , chemistry , biochemistry , membrane , metallurgy
Exact solutions are obtained for fluid flow induced by the heating of a borehole. The rock is modeled as a fluid‐saturated, porous, thermoelastic medium. The temperature and pore pressure fields are governed by a pair of diffusion equations, which are coupled through a source term in the pressure equation proportional to the temperature rate. The pressure profile exhibits a maximum that grows in magnitude and propagates away from the borehole. For a constant heat flux applied as an instantaneous step, the fluid flux to the borehole takes a finite initial value, and decays monotonically. When the heat flux exhibits a finite rise time, the fluid flux is initially zero, rises to a maximum, and then decays. At late time, the inverse of the fluid flux is linear in ln t ; this observation can be exploited to estimate the permeability and fluid diffusivity of low‐permeability rock. Sample calculations are shown for Westerly granite.