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Sensors 2018, 18(4), 1023; https://doi.org/10.3390/s18041023

Investigating Water Movement Within and Near Wells Using Active Point Heating and Fiber Optic Distributed Temperature Sensing

1
SelkerMetrics, LLC., 4225 SW Agate Lane, Portland, OR 97239, USA
2
Department of Biological and Ecological Engineering, Oregon State University, Corvallis, OR 97331, USA
*
Authors to whom correspondence should be addressed.
Received: 2 September 2017 / Revised: 29 January 2018 / Accepted: 31 January 2018 / Published: 29 March 2018
(This article belongs to the Special Issue Optical Sensors based on Micro/Nanofibres)
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Abstract

There are few methods to provide high-resolution in-situ characterization of flow in aquifers and reservoirs. We present a method that has the potential to quantify lateral and vertical (magnitude and direction) components of flow with spatial resolution of about one meter and temporal resolution of about one day. A fiber optic distributed temperature sensor is used with a novel heating system. Temperatures before heating may be used to evaluate background geothermal gradient and vertical profile of thermal diffusivity. The innovation presented is the use of variable energy application along the well, in this case concentrated heating at equally-spaced (2 m) localized areas (0.5 m). Relative to uniform warming this offers greater opportunity to estimate water movement, reduces required heating power, and increases practical length that can be heated. Numerical simulations are presented which illustrate expected behaviors. We estimate relative advection rates near the well using the times at which various locations diverge from a heating trajectory expected for pure conduction in the absence of advection. The concept is demonstrated in a grouted 600 m borehole with 300 heated patches, though evidence of vertical water movement was not seen. View Full-Text
Keywords: fiber optic; distributed temperature sensing; aquifer characterization; active temperature sensing; fluid velocity measurement; flow measurement; well measurement fiber optic; distributed temperature sensing; aquifer characterization; active temperature sensing; fluid velocity measurement; flow measurement; well measurement
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Selker, F.; Selker, J.S. Investigating Water Movement Within and Near Wells Using Active Point Heating and Fiber Optic Distributed Temperature Sensing. Sensors 2018, 18, 1023.

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