On a Transition Phase in Single Well Tests Data

In processing data of pumping tests of single wells at constant pumping rate the drawdown during the first fraction of minutes is modeled by a linear function of time as the well-bore storage. After a few minutes of pumping the drawdown is considered to be described by a solution of the Theis differential equation. The time span between these two ”regimes”is here named transition phase of the test. Models of this phase are suggested. These models were tested on a number of data sets, some results are shown in the closing part of this communication. It turns out that data in the transition phase contain significant information on the vicinity of the bore.