Patent ID: 7571768

Claim:
A method for creating a period of dynamic underbalance at a zone of interest in a wellbore comprising: positioning a perforation assembly in the wellbore at the zone of interest for creating an annulus between the assembly and the wellbore, the annulus containing fluid and having an initial hydrostatic pressure, the assembly having at least a perforation gun and one or more surge canisters; establishing an initial static density of the fluid in the annulus; actuating the perforating gun for creating an initial pressure event and forming perforations at the zone of interest and wherein dynamic pressure in the annulus reaches a first initial elevated pressure; measuring a dynamic density of the fluid in the annulus; delaying until the dynamic pressure diminishes from the first initial elevated pressure and the measured dynamic density is about the initial static density; and then opening at least one of the one or more surge canisters so as to receive a surge of the fluid therein for creating the period of dynamic underbalance.