Numerical simulation of pumping tests in multilayer wells with non-Darcianflow in the wellbore

An important feature of pumping in a multilayer system is the dynamic inter action between the aquifers via non-Darcian vertical flow within the wellbo re, An equivalent hydraulic conductivity (EHC) approach is used to include this transient interaction as a special leakage through the confining layer in the flow system. Different flow regimes (laminar and turbulent flows, a nd the transition range) are involved in a multilayer pumping test where th e relation between the hydraulic gradient and flow velocity is complicated. The change of flow regimes is accommodated by varying the content of EHC a s a function of the friction factor. For a particular well, the relation be tween friction factor and Reynolds number is unique and is obtained by inte rpolating Nikuradse's experimental results. A quasi-three-dimensional Galer kin finite-element method is used to integrate the vertical one-dimensional now in the wellbore and confining layers and the two-dimensional flow in t he aquifers, This approach makes it possible to couple the aquifer and well bore flows of different flow regimes and to salve them in a single numerica l framework based on the same linear relation between gradient and velocity . A carefully designed pumping test in a multilayer aquifer system near Bei hai City, Guangxi Autonomous Region, China, is used to demonstrate the perf ormance of the approach.