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Dilution Tests in a Low‐Permeability Fractured Aquifer: Matrix Diffusion Effect
Author(s) -
Bernstein Anat,
Adar Eilon,
Yakirevich Alexander,
Nativ Ronit
Publication year - 2007
Publication title -
groundwater
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.84
H-Index - 94
eISSN - 1745-6584
pISSN - 0017-467X
DOI - 10.1111/j.1745-6584.2006.00268.x
Subject(s) - borehole , tracer , permeability (electromagnetism) , geology , dilution , aquifer , diffusion , matrix (chemical analysis) , indicator dilution , porosity , geotechnical engineering , mineralogy , soil science , groundwater , materials science , chemistry , composite material , thermodynamics , medicine , biochemistry , physics , radiology , cardiac output , membrane , nuclear physics , blood pressure
A point dilution test is commonly used in single‐borehole tracer experiments designed to determine the Darcy velocity of a formation. This method is based on the concept that, in a borehole, a tracer’s concentration declines as a consequence of the water flux. Based on theoretical simulations and field observations, this study indicates that for low‐permeability, yet highly porous fractured formations, the common practice of excluding the effect of diffusive mass flux between the dissolved tracer within the borehole and the surrounding matrix may lead to significant errors in the assessment of the Darcy velocity. This conclusion was confirmed by a model adapted to simulate experimental data collected from a tracer test performed in a vertical, large‐diameter (25‐cm) borehole drilled along a subvertical fracture intersecting a chalk formation.