Estimation of Borehole Flow Velocity from Temperature Profiles

1. Introduction Method Analysis Conclusions Estimation of Borehole Flow Velocity from Temperature Profiles Maria Klepikova, Tanguy Le Borgne, Olivier Bour UMR 6118 CNRS University of Rennes 1, Rennes, France

2. Introduction Method Results Conclusions Plan • Introduction • Method • Temperature-depth profiles as precise flowmeter measurements • Comparison of temperature estimated flow velocities to flowmeter measurements • Estimation of fracture transmissivity, hydraulic head and connectivity • Conclusions

3. Introduction Method Results Conclusions Temperature profiles applications Determination of heat flow Estimation of groundwater flow Claude Jaupart et al. (1982) , A detailed study of the distribution of heat flow and radioactivity n New Hampshire (U.S.A.), Earth and Planetary Science Letters, 59, 267-287 M. Reiter (2001), Using precision temperature logs to estimate horizontal and vertical groundwater flow components, Water Resour. Res,37 (3),663-674

4. Introduction Method Results Conclusions Vertical borehole flows Frank Börner, Susann Berthold (2009), Groundwater Geophysics.

5. Introduction Method Results Conclusions Vertical borehole flows Frank Börner, Susann Berthold (2009), Groundwater Geophysics. Can we use temperature profiles to estimate borehole flows ?

6. Introduction Method Results Conclusions Temperature profile monitoring under different flow conditions The objective is to characterize fracture hydraulic properties and connectivity

7. Introduction Method Results Conclusions Borehole scale model for flow and heat transfer T is the temperature, a is the thermal diffusivity of fluid and rock, and v is the borehole flow velocity. v

8. Introduction Method Results Conclusions Temperature profiles are found to be very sensitive to borehole flow velocities V V The numerically obtained temperature profiles for borehole velocities varying from 0.1 mm/s to 1 cm/s, a typical range of borehole flow velocities observed in fractured formations under ambient conditions

9. Introduction Method Results Conclusions Temperature profile – inferred velocities for different flow conditions Measured temperature profile Inferred flow velocities

10. Introduction Method Results Conclusions Temperature profile – inferred velocities for different flow conditions Measured temperature profile Inferred flow velocities pumping rate Q=125L/min, drawdown s=1.9m

11. Introduction Method Results Conclusions Temperature profile – inferred velocities for different flow conditions Measured temperature profile Inferred flow velocities pumping rate Q=145L/min, drawdown s=0.6m

12. Introduction Method Results Conclusions Temperature profile – inferred velocities for different flow conditions Direct flow measurements: Indirect from temperature measurements:

13. Introduction Method Results Conclusions Estimation of the hydraulic properties from the temperature profiles Once the single and cross-borehole temperature profiles have been converted into flow profiles, the flow profiles can be interpreted to infer fracture hydraulic properties. We use the flow modelling approach proposed by Paillet (1998). B2-1 B2-2 B2-3 B2-4

14. Introduction Method Results Conclusions Conclusions • Temperature profiles are strongly sensitive to vertical borehole flow V • Vertical flow velocities deduced from the inversion of temperature profiles are in good agreement with direct flowmeter measurements • We have developed a methodology for characterizing spatially distributed hydraulic properties based on temperature profile measurement under ambient, single-borehole and cross-borehole pumping tests