16 research outputs found
Thermal-Plume fibre Optic Tracking (T-POT) test for flow velocity measurement in groundwater boreholes
International audienceWe develop an approach for measuring in-well fluid velocities using point electrical heating combined with spatially and temporally continuous temperature monitoring using Distributed Temperature Sensing (DTS). The method uses a point heater to warm a discrete volume of water. The rate of advection of this plume, once the heating is stopped, equates to the average flow velocity in the well. We conducted Thermal-Plume fibre Optic Tracking (T-POT) tests in a borehole in a fractured rock aquifer with the heater at the same depth and multiple pumping rates. Tracking of the thermal plume peak allowed the spatially varying velocity to be estimated up to 50 m downstream from the heating point, depending on the pumping rate. The T-POT technique can be used to estimate the velocity throughout long intervals provided that thermal dilution due to inflows, dispersion, or cooling by conduction do not render the thermal pulse unresolvable with DTS. A complete flow log may be obtained by deploying the heater at multiple depths, or with multiple point heaters
Active-distributed temperature sensing to continuously quantify vertical flow in boreholes
We show how a distributed borehole flowmeter can be created from armored Fiber Optic cables with the Active-Distributed Temperature Sensing (A-DTS) method. The principle is that in a flowing fluid, the difference in temperature between a heated and unheated cable is a function of the fluid velocity. We outline the physical basis of the methodology and report on the deployment of a prototype A-DTS flowmeter in a fractured rock aquifer. With this design, an increase in flow velocity from 0.01 to 0.3 m s−1 elicited a 2.5°C cooling effect. It is envisaged that with further development this method will have applications where point measurements of borehole vertical flow do not fully capture combined spatiotemporal dynamics
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Thermal-plume fibre optic tracking (T-POT) test for flow velocity measurement in groundwater boreholes
We develop an approach for measuring in-well fluid velocities using point electrical heating combined with spatially and temporally continuous temperature monitoring using distributed temperature sensing (DTS). The method uses a point heater to warm a discrete volume of water. The rate of advection of this plume, once the heating is stopped, equates to the average flow velocity in the well. We conducted thermal-plume fibre optic tracking (T-POT) tests in a borehole in a fractured rock aquifer with the heater at the same depth and multiple pumping rates. Tracking of the thermal plume peak allowed the spatially varying velocity to be estimated up to 50 m downstream from the heating point, depending on the pumping rate. The T-POT technique can be used to estimate the velocity throughout long intervals provided that thermal dilution due to inflows, dispersion, or cooling by conduction does not render the thermal pulse unresolvable with DTS. A complete flow log may be obtained by deploying the heater at multiple depths, or with multiple point heaters
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Active-Distributed Temperature Sensing to continuously quantify vertical flow in boreholes
We show how a distributed borehole flowmeter can be created from armored Fiber Optic
cables with the Active-Distributed Temperature Sensing (A-DTS) method. The principle is that in a flowing
fluid, the difference in temperature between a heated and unheated cable is a function of the fluid velocity.
We outline the physical basis of the methodology and report on the deployment of a prototype A-DTS
flowmeter in a fractured rock aquifer. With this design, an increase in flow velocity from 0.01 to 0.3 m s⁻¹
elicited a 2.5°C cooling effect. It is envisaged that with further development this method will have
applications where point measurements of borehole vertical flow do not fully capture combined
spatiotemporal dynamics.Keywords: Fiber optics, A-DTS, Flowmeter, Heated, Borehol
DRESS syndrome and agranulocytosis, a rare combination [Syndrome d'hypersensibilité médicamenteuse et agranulocytose, une association rare]
International audienc
Odeurs sexuelles chez les équidés : l'avis de l'étalon
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