Active-Distributed Temperature Sensing to continuously quantify vertical flow in boreholes

T. Read (1) , Olivier Bour (2) , J. S. Selker (3) , V. F. Bense (1) , Tanguy Le Borgne (2) , Rebecca Hochreutener (2) , Nicolas Lavenant (4)

1 School of Environmental Sciences [Norwich]
2 GR - Géosciences Rennes
3 Department of Biological and Ecological Engineering
4 Transferts d'eau et de matière dans les milieux hétérogènes complexes

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 s21 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: A-DTS; borehole; flowmeter; heated; fiber optics

Domains: Earth Sciences

T. Read, Olivier Bour, J. S. Selker, V. F. Bense, Tanguy Le Borgne, et al.. Active-Distributed Temperature Sensing to continuously quantify vertical flow in boreholes. Water Resources Research, 2014, 50 (5), pp.3706-3713. ⟨10.1002/2014WR015273⟩. ⟨insu-01005138⟩