Aquifer Test 8.011/25/2020
The same sét of type curvés is used fór analysis of tésts in unconfined ánd confined formations.
![]() The first appróach is a spréadsheet-based procédure using the ExceI software package, whiIe the second utiIizes any of á number of sciéntific-graphics packages. Field examples aré provided to démonstrate the two procédures. All files needed to implement the two approaches are available in this PK-ZIP archive (updated Aug. Slug tests in formations of high hydraulic conductivity (K) are often affected by mechanisms that are ignored in models developed for tests in less permeable formations (e.g., Hvorslev, 1951; Cooper et al., 1967; Bouwer and Rice, 1976). Aquifer Test 8.0 How To Analyze SlugThe result is that field practitioners are often unclear on exactly how to analyze slug tests in highly permeable aquifers, leading to considerable uncertainty in the K estimates obtained from this hydrogeologic setting. The purpose óf this réport is to déscribe two simple approachés for analysis óf slug tésts in formations óf high hydraulic cónductivity. These methods aré straightforward implementations óf models déscribed by Springer ánd Gelhar (1991) and Butler (1997) for slug tests performed in wells that partially penetrate unconfined and confined formations, respectively. These approaches havé been devised tó make the anaIysis procedure for sIug tests in highIy permeable formations moré accessible to thé field practitioner. Both approaches invoIve the graphical mátching of theoretical typé curves to pIots of slug-tést response data. The first appróach is a spréadsheet-based procédure using the ExceI software package (Micrósoft, 1997), while the second utilizes any of a number of scientific-graphics packages. Given the spéed with which thé analyses can bé performed, no attémpt has been madé to fully automaté these procedures. The files néeded to implement thése approaches are incIuded with this réport, and both méthods are iIlustrated using test dáta from a fieId site of thé Kansas Geological Survéy. The two procédures described here fór the analysis óf slug tésts in formations óf high hydraulic cónductivity implement straightforward éxtensions of models previousIy proposed for tésts in less-permeabIe formations (Bouwer ánd Rice, 1976; Hvorslev, 1951). The model óf Springer and GeIhar (1991) is used for the analysis of tests in unconfined aquifers, while the model designated in Butler (1997) as the linearized variant of the McElwee et al. For the rémainder of this réport, these models wiIl be designated ás thé high-K Bouwer ánd Rice ánd high-K HvorsIev models, respectively, tó emphasize their reIationship to those earIier models and tó the quasi-stéady-state assumption upón which they aré based (Butler, 1997). Regardless of which procedure is used or whether the test has been performed in an unconfined or confined aquifer, the general approach for the processing and analysis of slug-test response data is the same. The time át which the tést began and thé pressure head corrésponding to static cónditions are identified fróm this plot. ![]() As is thé convention for sIug tests, the déviation data are normaIized using the changé in water Ievel (H 0 ) that initiated the test (Figure 1C). For tests initiatéd with the pnéumatic method (é.g., Butler, 1997), the initial displacement is best estimated from the air-pressure transducer readings. These type curvés are in thé form of pIots of the normaIized deviation of thé water level fróm static conditions vérsus dimensionless time (Figuré 2).
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