Borehole Flowmeter Logging for the Accurate Design and Analysis of Tracer Tests

Abstract

Tracer tests often give ambiguous interpretations that may be due to the erroneous location of sampling points and/or the lack of flow rate measurements through the sampler. To obtain more reliable tracer test results, we propose a methodology that optimizes the design and analysis of tracer tests in a cross borehole mode by using vertical borehole flow rate measurements. Experiments using this approach, herein defined as the Bh-flow tracer test, have been performed by implementing three sequential steps: (1) single-hole flowmeter test, (2) cross-hole flowmeter test, and (3) tracer test. At the experimental site, core logging, pumping tests, and static water-level measurements were previously carried out to determine stratigraphy, fracture characteristics, and bulk hydraulic conductivity. Single-hole flowmeter testing makes it possible to detect the presence of vertical flows as well as inflow and outflow zones, whereas cross-hole flowmeter testing detects the presence of connections along sets of flow conduits or discontinuities intercepted by boreholes. Finally, the specific pathways and rates of groundwater flow through selected flowpaths are determined by tracer testing. We conclude that the combined use of single and cross-borehole flowmeter tests is fundamental to the formulation of the tracer test strategy and interpretation of the tracer test results.

Evaluating Flow Distribution in a Multiaquifer Recharge Well Using an In Situ Flowmeter

“…A number of researchers have employed borehole flowmeters to extrapolate depth‐dependent hydraulic conductivity and permeability variations in a range of aquifer conditions (e.g., Molz et al 1989; Rehfeldt et al 1992; Hanson and Nishikawa 1996; Ruud et al 1999; Zlotnik and Zurbuchen 2003; Basiricò et al 2015; Ren et al 2018). The theoretical relationships developed by Molz et al (1989) which assumes that the transmissivity of the vertical interval of measurement is directly proportional to net flow entering the screen segment between flowmeter readings, Q ( z ), have proven useful to quantify hydraulic conductivity independent of the type of flowmeter.…”

Characterization of preferential flow paths between boreholes in fractured rock using a nanoscale zero-valent iron tracer test

“…Flowmeter tests can be used to better characterize the vertical distribution of permeability in the borehole, providing more detailed information for the design of any tracer test and the interpretation of fracture flow pathways (Hess 1986;Williams and Paillet 2002;Lee et al 2012;Basirico et al 2015). A temperature Electronic supplementary material The online version of this article (doi:10.1007/s10040-016-1426-7) contains supplementary material, which is available to authorized users.…”