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Simulations to verify horizontal flow measurements from a borehole flowmeter.
Scott C James1, Richard A Jepsen, Richard L Beauheim
1Sandia National Laboratories, Geohydrology Department, Albuquerque, NM 87185-0735, USA. scjames@sandia.gov
Ground Water
|May 10, 2006
Summary
The scanning colloidal borescope flowmeter (SCBFM) accurately measures groundwater velocity in fractured rock wells. It shows potential for use in screened wells, though slot alignment affects accuracy.
Area of Science:
- Hydrogeology
- Environmental Engineering
- Geophysics
Background:
- Subsurface flow characterization is crucial for understanding groundwater movement and contaminant transport.
- Accurate measurement of groundwater velocity in wells is essential for effective resource management and remediation.
- Existing methods for measuring wellbore flow may have limitations in fractured or screened environments.
Purpose of the Study:
- To evaluate the performance of the scanning colloidal borescope flowmeter (SCBFM) in simulating subsurface flow conditions.
- To compare SCBFM measurements with numerical model simulations for both single fracture and multislot well screen scenarios.
- To assess the SCBFM's potential for quantifying groundwater flow in uncased and screened wells.
Main Methods:
- Experimental setup using a sand-tank flow chamber with a slotted acrylic tube representing a single fracture and a multislot well screen.
- Deployment of the scanning colloidal borescope flowmeter (SCBFM) to measure groundwater velocity (speed and direction) by imaging colloid movement.
- Development and application of numerical models to simulate flow fields and compare with experimental SCBFM data.
Main Results:
- For a single fracture scenario, SCBFM measurements of flow direction and speed near the well center showed good agreement with model simulations (speed within a factor of 1.5).
- In a multislot well screen, SCBFM accuracy was dependent on slot alignment with flow direction.
- Misaligned slots resulted in order-of-magnitude speed estimates and directional uncertainty of approximately +/-25 degrees.
Conclusions:
- The SCBFM shows promise as a tool for identifying and quantifying flowing features in uncased wells within fractured rock.
- The SCBFM's utility in screened wells is contingent on slot orientation relative to groundwater flow.
- Further calibration and validation are recommended for SCBFM application in complex wellbore geometries.