Permian Basin operators have recently achieved improved stimulation results using precision perforation breakdown prior to their stimulation treatments. Precision breakdown of individual perforations is made possible by a recently developed hook wall straddle packer that isolates intervals of casing as short as 3 in.
In previously used procedures, ball sealers, temporary blocking agents and high fluid injection rates were used to break down perforations. These methods were partially successful, but in some cases were detrimental to the stimulation and well performance due primarily to the fact that the operator did not know the status of the perforations at the time of the major stimulation.
The precision perforation breakdown method uses minimal pressure and pumping rate to help prevent fracturing into unwanted gas or water, and gives a positive indication that each perforation is broken down and will accept fluid. Values such as (1) instantaneous shut-in pressure and (2) perforation breakdown pressure can be obtained for individual perforations. This data is useful for designing the stimulation job and for design of subsequent jobs to be performed in the same field.
Subject paper discusses the conditions and circumstances under which precision perforation breakdown may be used to good advantage. Actual job logs and tool schematics illustrate the use of the precision breakdown method.