An Innovative Perforating Technique of Multiple Gun Sizes for Multiple Casing Sizes in Single Run

In certain cases, multiple production casing sizes are used across formations of the same pressure regime especially in vertical<br>or slightly deviated wells with long pay sections. The normal perforation practice would be to use a smaller gun size to<br>perforate the smaller lower casing section before making another perforating run with bigger gun size to perforate the upper<br>casing. Such perforating technique not only adds cost and time to the completion program but also reduces the efficiency of<br>the perforation tunnels due to damage caused by the completion fluids in the wellbore between the two perforation runs. In<br>addition, underbalanced perforation can only be performed on the first perforating run. Isolation of the first zone would be<br>required to create under-balance for the second run, thus adding cost and complexity to the operations.