Analyzing the recovery of a finite-diameter well after purging at an unknown rate -- a substitute for slug-testing

Journal Article · · Ground Water; (United States)

DOI:https://doi.org/10.1111/j.1745-6584.1994.tb00615.x· OSTI ID:5145912

Picking, L W ^[1]

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1. Stone and Webster Engineering Corp., Boston, MA (United States)

The formation parameters commonly determined by slug-testing a well can also be derived from the time-rate of recovery of the water level in the well following purging for a known period of time but at an unknown discharge rate, as is routinely done in preparation for obtaining water samples for laboratory analysis. By applying principles of superposition, recovery of a well when well-bore storage is important can be expressed in terms of the published large-diameter well function. Expressing recovery in a dimensionless form negates the need for the discharge rate. Using a microcomputer and simple extrapolation between the published solutions for the well function, type curves can be quickly calculated, plotted, and modified for fitting to the field data. Testing the formation in this manner eliminates the high gradients associated with slug-testing and permits maximum control over hydraulic stresses so that mobilization of colloids can be minimized. Also, by combining formation hydraulic testing with the sampling routine, a saving in effort and time should be realized over the traditional slug-test, wait-for-stabilization, purge and sample procedure. Accuracy of the method is at least comparable to that of a slug-test analysis for practical purging times.

• OSTI ID: 5145912
• Journal Information: Ground Water; (United States), Journal Name: Ground Water; (United States) Vol. 32:1; ISSN GRWAAP; ISSN 0017-467X
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
AQUIFERS
ENVIRONMENTAL QUALITY
EQUATIONS
HYDRAULIC CONDUCTIVITY
SAMPLING
WATER QUALITY