Diagnostic plots
The diagnostic plot is a log-log plot of the pressure change and pressure derivative (vertical axis) from apressure transient test vs. elapsed time (horizontal axis). Figure 1 shows an example of a diagnostic plot. The diagnostic plot can be divided into three time regions: early, middle, and late. At the earliest times on a plot (the early-time region), wellbore and near-wellbore effects dominate. These effects include wellbore storage, formation damage, partial penetration, phase redistribution, and stimulation (hydraulic fractures or acidization).
March, 2016