A section of pipe connected to the upper part of the drill bit to accommodate and protect the core during core barrel. This article will introduce the classification of core barrel.

This article contains the following:

What is core barrel?

Single layer core barrel

Double-tube core barrel

1.What is core barrel?

A section of pipe connected to the upper part of the drill bit to accommodate and protect the core during core barrel. When drilling, it also plays the role of guiding drill. The ordinary core barrel is just a seamless steel tube with threaded ends at both ends, and the diameter is slightly smaller than the drill bit (2 to 4 mm smaller). A single core barrel is 3 to 45 meters long. To prevent bending of the borehole, several core barrels can be connected to form a long and thick diameter drilling tool. When drilling in special formations (such as loose and broken formations), special core barrels are often used, such as double-layer core barrels.

2.Single layer core barrel

Single tube drilling tool has a simple structure and convenient processing. It is a core tool used for drilling cemented carbide and steel particles. Because the flushing fluid in the single-pipe drilling tool is fed into the core pipe by the drill pipe. Drilling parts that directly rush to the top of the core, and the impact and friction of the core barrel rotation on the core, the core is very easy to wear, so it is only suitable for relatively complete and stable formations.

3.Double-tube core barrel

Drilling tools used to extract and protect rock (mine) cores in loose, broken formations or coal seams. There are two types of double-layer core barrels: double-acting and single-acting. The double-acting core barrel is the rotation of the inner and outer core barrel following the drill bit and the drill rod. It is used in the formation of loose or broken strata that is not serious. The inner and outer tubes of the single-acting double-layer core barrel are bearing isolated. The broken stratum can protect the core well. A double-layer core barrel is used to take the core, and the drill bit needs to use an alloy drill bit or a diamond drill bit with a thick wall. As the area of the lip surface of the drill bit contacting the rock increases, the efficiency of drilling with a double-layer core barrel is lower than that of an ordinary core barrel. In the mine bed and coal bed, in order to ensure the rock (mine) core adoption rate, it is stipulated that a double-layer core pipe must be used to take the core. The more complex double-layer core barrel, in addition to being made into a single action, is also placed inside the inner tube of aluminum, steel or plastic buckle half-closed tube, to play a better role in protecting the core. The blocking of the core of the double-layer core barrel and the lower port that seals the inner core barrel are accomplished by installing a core snap (clamp, circlip, claw spring, etc.) in the bit.