RIASSUNTO
Abstract
Gulf of Suez Petroleum Company (GUPCO) introduced in 1984 the technique of perforating underbalance with a tubing conveyed gun. The early results of the first runs were very encouraging.
Since then, tubing conveyed perforation has become standard practice for nearly all new completions, workovers, and drill stem tests. The tubing conveyed perforating system has reduced completion time, reduced formation damage, and maximized well production. production. This Article presents Gupco's evaluation of the tubing conveyed perforation (TCP), discusses the operational aspects of this technique, and the results of its application.
Introduction
Underbalanced perforation (perforating with the pressure in the well bore lower than the formation pressure in the well bore lower than the formation pressure) is generally considered the most pressure) is generally considered the most successful method of perforation in Gulf of Suez Operations. Perforating underbalance with tubing conveyed gun gives deep, large diameter, and clean Damage may be caused by the completion fluid, the cement, the crushed zone of the formation, and the debris of the perforation charges.
A total of 183 TCP jobs have been performed in Gulf of Suez since the introduction of the tubing conveyed gun technique (Fig. 1). Four-shots per foot, 3-3/8"" (8.6 cm) guns represent 60% of the total guns, and averaged 110 ft (35.5 m); four-shot per foot, 5"" (12.7 cm) guns represent 16% of per foot, 5"" (12.7 cm) guns represent 16% of total runs with an average job size of 93 ft (28.3m). Also, 5"" (12.7 cm) high shot density guns (9-12 SPF) represent 24% of the total with an average job size of 110 ft (33.5m). High temperature jobs represent 42% of the total. In 30% of the runs, the gun was released to bottom after firing.
With the tubing conveyed perforating technique we have been able to eliminate most of the problems associated with conventional wire line problems associated with conventional wire line methods. Minor problems have been experienced with tubing conveyed gun technique; these problems are addressed more fully after problems are addressed more fully after discussing the underbalance techniques.
II. UNDERBALANCE TECHNIQUES AND TCP OPERATIONS
The basic TCP technique involves running a large-diameter casing gun on tubing below the production packer. Tubing is run dry or production packer. Tubing is run dry or partially filled to establish the desired partially filled to establish the desired underbalance. The tubing assembly (fig. 2) has a radioactive reference sub installed one joint above the packer. The assembly is positioned at the desired depth of correlating the radioactive sub with a gamma ray or neutron tool and the packer is set after spacing out. The gun is packer is set after spacing out. The gun is typically equipped with a top-mounted percussion-type firing device. By dropping a percussion-type firing device. By dropping a detonating bar down the tubing a vent valve below the packer is opened just before firing. This communicates casing below the packer with the tubing. On firing, fluid surges into the casing and, through the vent ports, into the tubing. Gun firing is monitored by the noise produced by the detonation or shock transducers produced by the detonation or shock transducers attached to the tubing at the surface. The gun may then be pulled or released from the string and dropped to bottom to permit future operations through full-opened tubing.