Effectiveness of Gun Perforating

Abstract

Published in Petroleum Transactions, AIME, Volume 201, 1954, pages 34–40. Abstract Laboratory and field tests during the past five years indicated considerable variation in the penetrating power of commercially available gun perforators. Many of the guns which achieved inadequate penetration in these tests have since been improved. However, recent productivity tests indicated the possibility of inadequate penetration or, at least, ineffective penetration in some wells. Laboratory experiments under simulated well conditions have demonstrated considerable plugging of the perforations, apparently as a result of factors associated with the shooting process and/or the drilling mud in the well at the time of perforating. The restrictions to (tow per unit of hole depth caused by this plugging appears to be greater for jet perforators than for bullet guns of comparable diameter; however, because of the greater depth of penetration obtained with the jet guns, the total flow rates appear to be approximately equal. Limited testing with an experimental shaped charge suggests that less shot hole restriction and greater flow rates may result from larger-diameter perforations or other factors related to charge design. Introduction Gun perforating has been accepted for a number of years as a routine well completion method which is often preferred since it permits more selective operation of producing zones. Nevertheless, questions have continued to arise as to the effectiveness of the communication paths established between the productive formation and the interior of the casing. The basis for these questions has generally been failure to obtain anticipated fluid production rates through gun perforated completions in specific wells. These low productivities, together with the frequent recovery of bullets from well bores, were considered strong evidence of inadequate penetration. Laboratory investigations of the penetration performance of many of the bullet. guns available as late as 1948 gave support to these indications. Subsequent electrical analog studies indicated that the depth of penetration required to provide productivities equivalent to open hole was beyond the capacity of most bullet perforators evaluated in the early laboratory penetration tests.