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Slug Test Analysis


What is it?

Slug testing is a method to determine aquifer hydraulic conductivity or transmissivity by observing how the head in a well returns to equilibrium after removing or adding a "slug" (volume of water or other dense material).
Slug tests are easier to conduct than pump tests as they can be conducted with a single well, and no pumping equipment is required. However, with a slug test the portion of the aquifer "sampled" may be less representative of the aquifer as a whole. In general the following assumptions are used when conducting slug test analyses:
-the aquifer has an infinite areal extent, and is homogeneous and of uniform thickness.
-the watertable is initially horizontal,
-the propogated head change is instantaneous.

Bouwer & Rice (1976)

How to use it:

Choose or Input Well Geometry and Observed Data

The user can enter their own data or choose to analyze an example dataset.
Example data sets:
-USGS Bouwer-Rice .xls
-AQTest

Pick Method and Run Analysis

Several methods for analyzing slug tests are provided.
 
MethodAdd'l. AssumptionsNotes
Bouwer-Rice (1976)well can be fully or partially penetrating in confined or unconfined AQ, flow is steady. The user must choose a shape factor equation (analytical formulations of Bouwer-Rice solution).**
Hvorslev (1951)well can be fully or partially penetrating in confined or unconfined AQ, flow is steady
Cooper (1967)well is fully penetrating, flow to well is horizontal, AQ is nonleaky confined, flow is unsteady, water is released instantaneously from storageThis method uses type curve matching, storage parameter (ε) should be entered after matching the curve



Additional References

**Bouwer-Rice shape factors:
-DeBisschop 3% reported error for small values of B, otherwise <1%.
-Yang & Yeh, 2004(2008) <10% reported error.
-Butler, 1998. The Design, Performance, and Analysis of Slug Tests (1st ed.), Lewis Publishers, New York, 252p.

Cooper, Bredehoeft and Papadopulos (1967)

Hvorslev (1951)