Semi-analytical solution for radial solute transport model with skin effect

Radial tracer test is one of the most effective ways to estimate aquifer transport parameters.However, traditional tracer tests usually neglect skin effect near a pumping well, due to extensive well development resulting in anomalous hydrogeological properties.A semi-analytical model for a confined aquifer was developed to analyze the effects of skin of hydrogeological properties on breakthrough curves.The Laplace transform and numerical inverse Laplace methods were used to solve the model.The results indicate that a larger dispersivity in the skin zone results in higher values of breakthrough curves (BTCs) at the early injection stage, and higher peak values of BTCs; however, larger effective porosity in the skin zone results in lower values of the BTCs at the early injection stage but generates higher values at the late stage; besides, an abrupt change for the spatial concentration distribution was observed at the interface of the skin and aquifer formation zones due to the change of dispersivity in the skin zone.The general conclusion is that the possible impacts of skin on radial solute transport are significant and should be taken into consideration in tracer-injection tests.