Use of cumulative volume of constant‐head injection test to estimate aquifer parameters with skin effects: Field experiment and data analysis

Abstract

[1] In a silty sand aquifer, constant-head injection tests (CHITs) were performed for the determination of aquifer parameters. In a CHIT the test well is overflowed by the injection of surface water. The difference between the injection flow and the overflow measured by an automated system directly yields the cumulative volume V w (t) that enters the aquifer. Therefore the method of using V w (t) in determining the aquifer transmissivity and the storage coefficient is developed, where well skin effects are taken into account. The semilog plot of t/V w (t) is useful in indicating whether well skin exists around the constant-head pumping well. If well skin is absent, the semilog plot of t/V w (t) shows a straight line at large times, from which the transmissivity and the storage coefficient can be determined. If well skin exists, the semilog plot of t/V w (t) exhibits two straightline sections occurring at small and large times, respectively. Then only the transmissivity can be determined from the slope of the large-time straight line. In this event, aquifer drawdown/buildup observed at observation wells is needed for the determination of the storage coefficient. In fact, both the transmissivity and the storage coefficient can be determined with aquifer drawdown/buildup normalized with respect to V w (t), regardless of well skin around the constant-head pumping well. Once T and S are known, the skin factor of the constant-head pumping well can be obtained from t/V w (t).

Steady flows driven by sources of random strength in heterogeneous aquifers with application to partially penetrating wells

“…The study of well flows is particularly useful for the determination of the aquifer hydraulic properties (e.g., Jones et al 1992;Chen and Chang 2002), controlling the off-site migration of contaminated groundwater (Hiller and Levy 1994), or recovering light non-aqueous phase liquids (Murdoch and Franco 1994). Under field conditions, wells usually partially penetrate aquifers (especially when the aquifer thickness is large).…”

Recent advances in modeling of well hydraulics

“…Thus the well productivity ratio becomes very small when K skin tends zero and it depends only on drainage, wellbore and skin radius when K skin tends to be a large value. Hawkin's skin factor has been adopted in CHTs, CRTs and slug tests by, for example, Faust and Mercer [58] and Chen and Chang [164]. Moench and Hsieh [165] considered an equation for describing the flow in skin zone with negligible storativity and provided a hydraulic head solution for the slug test.…”

An improved neural network approach to the determination of aquifer parameters

“…The determination of aquifer parameters has always been a challenging task for groundwater resources engineers and managers (for example, Jacob, 1940;Hantush, 1956;Walton, 1962;Wikramaratna, 1985;Aziz and Wong, 1992;Zhan et al, 2001;Chen and Chang, 2002;Balkhair, 2002;Chen and Chang, 2003), because it holds a central position in groundwater modeling. The aquifer parameters obtained by the type-curve graphical method (Jacob, 1940) are of questionable reliability (Aziz and Wong, 1992;Balkhair, 2002).…”