Multi-level slug tests in highly permeable formations: 1. Modification of the Springer-Gelhar (SG) model

A multi-level slug test model and a method for the evaluation of vertical profiles of hydraulic conductivity in highly permeable formations are developed. A double-packer system is employed to estimate local hydraulic conductivity. Depending on the formation and double-packer system parameters, the water level recovery in the tested well can exhibit a monotonic or oscillatory response, To discern information on aquifer properties from artifacts introduced by the measurement system, the theory of flow in an aquifer and a double-packer system is developed. The mathematical model incorporates features of the Springer and Gelhar (1991) model and reduces to the Bouwer and Rice (1976) model in a special case. The model involves equations of momentum and mass conservation for the double-packer system with quasi-steady well-aquifer interaction equations, The method is uniformly applicable for both monotonic and oscillatory well responses and can produce profiles of hydraulic conductivity for the tested well. The criterion is given to determine the type of well response for given slug test conditions, (C) 1998 Elsevier Science B,V.