Shaped charge perforating bullets are the most widely used perforating bullets and also the most efficient perforating bullets. The common structure of a gun-body shaped charge perforating bullet mainly includes a shell, a detonator, a main explosive and a charge cap. The shell is mostly a steel shell, and the primary requirement is the pressure bearing capacity, which should ensure the formation of an ideal jet shape. The main explosive is the energy source for the formation of the shaped jet, and is a high-energy solid explosive. The detonator is an explosive of the same type as the main explosive, but with higher sensitivity, and is used to detonate the main explosive. The function of the charge cap is to generate a jet beam after the main explosive explodes to form a perforating channel. The shape and quality of the perforating channel are mainly determined by the material and structure of the charge cap, and the perforating bullet cap is generally conical.
Shaped charge perforating bullets can be divided into two categories according to their use: gun-body shaped charge perforating bullets and gun-free shaped charge perforating bullets; according to the temperature resistance level, they can be divided into three types: normal temperature, high temperature and ultra-high temperature perforating bullets; according to the perforation type, they can be divided into two types: deep penetration perforating bullets and large aperture perforating bullets.
The gun body shaped perforating bullet is installed in a sealed gun body, and the shell is protected outside the charge column, which improves the effective utilization rate of the charge. Under the same charge amount conditions, the penetration index is better than that of the gun body shaped perforating bullet. With the protection of the gun body of the perforating gun, the perforating bullet does not contact the well fluid and does not withstand external pressure.
The gun body shaped perforating bullet is a perforating bullet that does not use a sealed gun body. The perforating bullet adopts a single sealing structure, which can directly isolate the well fluid and withstand external pressure. When used, it is connected in series with a bullet rack or a non-sealed steel pipe and then lowered into the well. During the perforating process, the explosion products of the perforating bullet directly act on the casing, and the fragments fall directly to the bottom of the well after the explosion. Limited by the inner diameter size of the casing and the tubing, its penetration depth and temperature and pressure resistance indicators are all low.