Evangeline Section Meeting on Drilling and Production Practices on the Gulf Coast, 24 April, Lafayette, Louisiana
The two basic problems associated with the design of high performance, small diameter, fixed charge, expendable perforators have been resolved in a new 1-3/8-in. diameter gun for use through 1.5-in. production tubing.
A new method to control gun clearance and a new firing system which fully utilizes internal carrier space were developed and are described herein. This new combination, in a given gun design, is found to offer maximum and consistent performance on all shots irrespective of casing size.
Developments in permanent-type completion operations within the past few years have resulted in multiple-string completions in which two or more sands are produced independently and simultaneously from the same well. Due to casing diameter restrictions, this technique has necessitated the use of small bore 1.5-in. production tubing which must be negotiated by the expendable shaped charge tool in order to perforate the well.
For a through-tubing tool to pass freely through this small bore tubing it must have a diameter not exceeding 1–3/8-in. Such a tool was introduced to the field during 1955 in the form of a swing tool. Mechanical difficulties with this gun, however, emphasized the need for a simpler, more reliable tool; one which would offer high charge performance in the common casing sizes in spite of small gun diameter restrictions. A gun was also needed to shoot small diameter liners below 1.5-in. tubing.
Fixed charge guns of the capsule or tubular type are considerably more trouble free than swing guns. However, a preliminary study of conventional capsule and tubular gun designs in the 1–3/8-in. diameter immediately revealed two basic problems which greatly influenced gun performance:
large gun to casing clearances and
lack of internal carrier space for charge components.