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

Journal of Hydrology
By: , and 

Links

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.
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
Contributing office(s) Toxic Substances Hydrology Program
Description 14 p.
First page 223
Last page 236
Google Analytic Metrics Metrics page
Additional publication details