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Performance and Analysis of Drillstem Tests in Small‐Diameter Boreholes
Author(s) -
Marinelli Fred,
Rowe Jerry W.
Publication year - 1985
Publication title -
groundwater
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.84
H-Index - 94
eISSN - 1745-6584
pISSN - 0017-467X
DOI - 10.1111/j.1745-6584.1985.tb00782.x
Subject(s) - borehole , coring , slug test , hydraulic conductivity , geology , compressed air energy storage , petroleum engineering , geotechnical engineering , environmental science , soil science , engineering , energy storage , drilling , soil water , mechanical engineering , power (physics) , physics , quantum mechanics
While drillstem tests have been used extensively in the petroleum industry to obtain reliable measurements of hydraulic parameters in single boreholes, the technique has been used only to a limited extent in ground‐water investigations. This is due in part to the limited availability and high cost of suitable equipment for small‐diameter boreholes. In this study, drillstem tests were performed in exploratory boreholes to evaluate the hydraulic characteristics of a proposed compressed air energy storage site in central Illinois. The tests were conducted in small‐diameter coreholes (vertical and inclined) at depths up to 610 meters (2000 ft) using a drillstem tool designed and field‐tested by the authors. Field data were analyzed using semilog and curve‐matching techniques. Values of hydraulic conductivity obtained by the two methods were generally in very good agreement. The curve‐matching method allowed for calculation of wellbore storage and an estimation of well‐bore damage (skin effect). Test results indicate that exploratory boreholes were severely damaged by the coring process. In the presence of wellbore damage, slug test hydraulic conductivities were significantly lower than those given by drillstem tests conducted in the same zones. The sole use of slug tests would have underestimated hydraulic conductivity and led to erroneous conclusions regarding site conditions. The drillstem test methodology described herein offers a cost‐effective technique for measuring representative values of hydraulic conductivity in single boreholes.