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Estimating formation properties from early-time recovery in wells subject to turbulent head losses

Journal of Hydrology

By:
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DOI: 10.1016/S0022-1694(98)00170-X

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Abstract

A mathematical model is developed to interpret the early-time recovering water level following the termination of pumping in wells subject to turbulent head losses. The model assumes that turbulent head losses dissipate immediately when pumping ends. In wells subject to both borehole storage and turbulent head losses, the early-time recovery exhibits a slope equal to 1/2 on log-log plots of the recovery versus time. This half-slope response should not be confused with the half-slope response associated with a linear flow regime during aquifer tests. The presence of a borehole skin due to formation damage or stimulation around the pumped well alters the early-time recovery in wells subject to turbulent head losses and gives the appearance of borehole storage, where the recovery exhibits a unit slope on log-log plots of recovery versus time. Type curves can be used to estimate the formation storafivity from the early-time recovery data. In wells that are suspected of having formation damage or stimulation, the type curves can be used to estimate the 'effective' radius of the pumped well, if an estimate of the formation storativity is available from observation wells or other information. Type curves for a homogeneous and isotropic dual-porosity aquifer are developed and applied to estimate formation properties and the effect of formation stimulation from a single-well test conducted in the Madison limestone near Rapid City, South Dakota.A mathematical model is developed to interpret the early-time recovering water level following the termination of pumping in wells subject to turbulent head losses. The model assumes that turbulent head losses dissipate immediately when pumping ends. In wells subject to both borehole storage and turbulent head losses, the early-time recovery exhibits a slope equal to 1/2 on log-log plots of the recovery versus time. This half-slope response should not be confused with the half-slope response associated with a linear flow regime during aquifer tests. The presence of a borehole skin due to formation damage or stimulation around the pumped well alters the early-time recovery in wells subject to turbulent head losses and gives the appearance of borehole storage, where the recovery exhibits a unit slope on log-log plots of recovery versus time. Type curves can be used to estimate the formation storativity from the early-time recovery data. In wells that are suspected of having formation damage or stimulation, the type curves can be used to estimate the `effective' radius of the pumped well, if an estimate of the formation storativity is available from observation wells or other information. Type curves for a homogeneous and isotropic dual-porosity aquifer are developed and applied to estimate formation properties and the effect of formation stimulation from a single-well test conducted in the Madison limestone near Rapid City, South Dakota.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Estimating formation properties from early-time recovery in wells subject to turbulent head losses
Series title:
Journal of Hydrology
DOI:
10.1016/S0022-1694(98)00170-X
Volume
208
Issue:
3-4
Year Published:
1998
Language:
English
Publisher:
Elsevier Sci B.V.
Publisher location:
Amsterdam, Netherlands
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Hydrology
First page:
223
Last page:
236
Number of Pages:
14