Gringarten-Witherspoon Solution for Fractured Aquifers with a Single Vertical Plane Fracture
Description
A mathematical solution by Gringarten and Witherspoon (1972) is useful for determining the hydraulic properties (hydraulic conductivity, specific storage, hydraulic conductivity anisotropy and fracture length) of fractured aquifers with a single vertical plane fracture intersecting the pumped well. Analysis involves matching the solution to drawdown data collected during a pumping test. The solution estimates hydraulic conductivity anisotropy in a horizontal (x-y) plane.
AQTESOLV provides visual and automatic methods for matching the Gringarten and Witherspoon solution to pumping test and recovery test data. This easy-to-use and intuitive software promotes rapid and accurate determination of aquifer properties.
Assumptions
The following assumptions apply to the use of the Gringarten and Witherspoon solution for a vertical fracture:
- aquifer has infinite areal extent
- aquifer has uniform thickness
- aquifer potentiometric surface is initially horizontal
- fractured aquifer represented by anisotropic nonleaky confined system with a single plane vertical fracture that fully penetrates aquifer
- flow is unsteady
- water is released instantaneously from storage with decline of hydraulic head
- diameter of control well is very small so that storage in the well can be neglected
Solution Options
AQTESOLV provides the following options for the Gringarten and Witherspoon vertical fracture solution:
- variable pumping rates
- multiple pumping wells
- multiple observation wells
Benchmark
Comparison of AQTESOLV (blue line) and published uniform-flux vertical plane fracture well function values (symbols) at the wellbore (Gringarten and Witherspoon 1972).
References
Gringarten, A.C. and P.A. Witherspoon, 1972. A method of analyzing pump test data from fractured aquifers, Int. Soc. Rock Mechanics and Int. Assoc. Eng. Geol., Proc. Symp. Rock Mechanics, Stuttgart, vol. 3-B, pp. 1-9.
See also: solution methods, pumping tests