SNO H+ : Modelling borehole flows from Distributed Temperature Sensing data to monitor groundwater dynamics in fractured media.

Fractured aquifers are known to be very heterogeneous with complex flow path geometries. Their characterization and monitoring remain challenging despite the importance to better understand their behavior at all spatial and temporal scales. Heat and correspondingly temperature data have gained much interest in recent years and are often used as a tracer for characterizing groundwater flows. In the current work,a fast computer code is developed using Ramey and Hassan and Kabir analytical solutions which converts the temperature profile to the flow rate profile along the borehole. The method developed is validated through numerical simulations. A global sensitivity study recognizes the media thermal properties as the most influential parameters. For testing the method in the field,fiber-optic distributed temperature sensing (FO-DTS) data were used to monitor the dynamic behavior of fractured aquifers at the borehole scale at the Ploemeur-Guidel field site in Brittany,France. DTS data are used to infer the flow rates in the different sections of a fractured wellbore (flow profile) and calculate the contribution of each fracture to the total flow. DTS data were acquired for about three days in three different hydraulic conditions corresponding to two different ambient flow conditions and one pumping condition. Flow profiling using distributed temperature data matches satisfactorily with results from heat-pulse flow metering performed in parallel for cross-checking. Moreover,flow profiling reveals the daily variations of ambient flow in this fractured borehole. Furthermore,it shows that during ambient flowing conditions,shallow and deep fractures contribute roughly equally to the total flow while during the pumping condition,the deepest fractures contribute more to the total flow,suggesting a possible reorganization of flow and hydraulic heads depending on the hydraulic conditions. Thus,although the proposed method (DTS data and proposed framework) may be costlier and is based on indirect characterization through temperature measurements,it provides real-time monitoring of complex fracture interactions and recharge processes in fractured media. Thus,this method allows for a full analysis of the temporal behavior of the system with a simple and fast analytical model. Furthermore,thanks to its narrow width,DTS can be used and installed in boreholes for long-term monitoring while heat-pulse flow metering may lead to head losses in the borehole and may not be always possible depending on some borehole conditions. One of the limitations of the approach proposed is the proper knowledge of the thermal properties of media required to infer the flow rate from the temperature. Nevertheless,surface rate measurement can be useful to constrain these properties and reduce the flow profiling uncertainty. Thus,the method proposed appears to be an interesting and complementary method for characterizing borehole flows and groundwater dynamics in fractured media such as for instance,monitoring the recharge dynamic

Date (Creation): 2021-01-01

Citation identifier: SNO-HPLUS-POULADI-ET-AL

Cited responsible party

Organisation name	Individual name	Electronic mail address	Role
UMR6118-Geosciences Rennes		behzad.pouladi@univ-rennes1.fr	Author

Presentation form: Digital map

Purpose: test

Point of contact

Organisation name	Individual name	Electronic mail address	Role
UMR6118-Geosciences Rennes		behzad.pouladi@univ-rennes1.fr	Author
UMR6118-Geosciences Rennes		hplus-contact@univ-rennes1.fr	pointofcontact

Maintenance and update frequency: As needed

Resource format

Name	Version
text/csv

Inspire

Gemet

Continents, countries, sea regions of the world

france
brittany

Keywords

fractured media
borehole flow
flow profiling
distributed temperature sensing
heat pulse flow metering

Use limitation: CC BY-NC-SA International 4.0

Access constraints: Restricted

Use constraints: License

Other constraints: Ask for the supplier for the accuracy,updating,integrity and completeness of the data. Access and use of H+ data policy are subject to H+ data policy,please see the agreements on H+ web site : http://hplus.ore.fr/public/Terms_and_agreements_Hplus_README_en.pdf

Language: English

Character set: UTF8

Topic category

Geoscientific information
Environment
Inland waters

Begin date: 2019

End date: 2021

Reference system identifier: EPSG / 4326

OnLine resource

Protocol	Linkage	Name
WWW:LINK-1.0-http--link	https://hplus.ore.fr/en/pouladi-et-al-2021-joh-data	Data on H+ data
WWW:LINK-1.0-http--link	http://hplus.ore.fr	Information on H+ website
WWW:DOWNLOAD-1.0-http--download	https://hplus.ore.fr/documents/requests/guidel/Guidel_PZ26_FO_DTS_Pouladi.csv.tgz	Guidel_PZ26_FO_DTS_Pouladi
WWW:DOWNLOAD-1.0-http--download	https://hplus.ore.fr/documents/requests/guidel/Guidel_Flowmetry_PZ26_Pouladi.csv.tgz	Guidel_Flowmetry_PZ26_Pouladi
WWW:LINK-1.0-http--link	https://doi.org/10.1016/j.jhydrol.2021.126450	publication