Important Pressure Transient Analysls Equations

In the equation for skin factor during the pressure buildup, P, is measured just before shutting in the well, and plhr is obtained from the straight-line portion (extrapolated if necessary) of the buildup curve one hour after shut-in (see Figure 5-138a). Similarly, the straight-line portion of the drawdown data must be extrapolated to one hour if the data do not fall on the semilog straight-line (see Figure 5-138b).