ABSTRACT:

Flow efficiency of perforated completions has been a major concern since the first use of gun perforating. Inadequate efficiency was initially attributed to the restricted area available for flow compared to the larger flow area of an openhole completion of the same thickness. Subsequent experimental studies indicated that mild improvements in perforating parameters, e.g. penetration and shot density, will make the flow efficiency of a perforated system at least as good if not better than that of an openhole completion of comparable thickness. Nevertheless, even with improved perforation parameters, field performance continued to fall short of theoretically predicted results. More recent investigations indicated that productivity is influenced not only by perforation geometry but also by formation characteristics and perforating environment, with all three factors interacting in a complex manner. In 1998, Belayim Petroleum Company (Petrobel) launched a project to identify its damaged wells and to measure their actual P.I. using different techniques. Wells were categorised based on their completion factors (the ratio of actual P.I. to theoretical P.I.), and workover priorities were accordingly established to optimize production. One of the most successful techniques used by Petrobel to cure the damage was to re-perforate the damaged wells with deep penetrating gun charges. This paper highlights the damage problem, discusses the logic behind the use of deep-penetration perforation, and presents the successful work performed in several wells leading to optimum production.

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