What is a Core Barrel?

A core barrel is an essential tool in geological drilling, designed to retrieve cylindrical rock samples from deep within the Earth. Its robust construction allows geologists to analyze sub-surface formations, unlocking secrets of our planet's history and resources. Intrigued by how these samples can predict natural events or lead to resource discoveries? Dive deeper into the fascinating world of core barrels with us.
Anna B. Smith
Anna B. Smith

A core barrel is a cutting device that is circular in design, with an open center portion. This piece of machinery is typically used to cut through extremely hard surfaces, such as rock bottomed sea floors and steel reinforced concrete. There are three primary types of core barrel drills: standard barrels, diamond barrels, and rotating barrels. This type of equipment is typically utilized by industrial construction companies and geological survey teams.

The core barrel is typically mounted to stabilizing equipment, such as a drilling rig or a truck rig, which can be operated by fewer workers and used for smaller cores. The barrel itself is made from a variety of hardened materials, like steel and titanium, that are designed to withstand large amounts of pressure, and features a row of cutting teeth along the bottom edge. The teeth may be made from similar materials as the drill itself, and are often reinforced with additional metals for heavy duty jobs. These drills are manufactured in a variety of sizes, and often can be designed to the specifications of the purchasing company. Some drill types feature an additional drilling inner core.

An offshore oil platform. A core barrel is often used to cut through the rocky sea floor during drilling.
An offshore oil platform. A core barrel is often used to cut through the rocky sea floor during drilling.

A rotating core barrel is a two part drill system that is comprised of a spinning drill bit which moves around a non-rotating inner core. This type of drill is often used to penetrate the hard, crusty rock at the bottom of the ocean, and is frequently found in use on off shore oil rigs for drilling wells. The drill rests on the surface of the rock and begins spinning down into the hardened sediment. The interior non-rotating core may be inserted periodically to take samples of the rock for analyzing. The stationary core can be removed at any time and replaced with a secondary rotating drill for added force.

A diamond core barrel is similar to the rotating core. It employs an inner and outer core to obtain rock and mineral samples during the drill process. The diamond bit, however, is used in instances where the materials are too hard for a standard rotating barrel to penetrate. The diamond bit may be inserted into the existing well, and then rotates the outer barrel around the inner barrel to cut away the sample. This technique is also beneficial in preventing any exterior water from entering the core sample during the extraction process, which is a primary concern when drilling in the ocean.

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Discussion Comments


@allenJo - I doubt it. From what I understand the core drilling machine operates at one level and the earthquakes happen at another level. I think it would take a powerful force to trigger a movement in the tectonic plates actually.

I don’t believe that drilling equipment can do that. Oil companies are not drilling massive holes. They are looking for holes that are just big enough for them to be able to pump oil out of. I think they can do this without too much disruption to the surrounding environment.


Lately we’ve had a string of earthquakes in our area. Honestly it’s the first time in my life I’ve ever experienced an earthquake. In the part of the country where we live (the Midwest), earthquakes are not that common – at least not the kind that you feel. But we’ve felt them all right, sometimes back to back.

Anyway, because of the unusual occurrences, some people have speculated that it’s the fault of the oil companies. These people think that it’s the core drilling equipment punching through the earth that is triggering the earthquakes, jolting the fault lines and stuff. I don’t know if they’re correct but sometimes I wonder.

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    • An offshore oil platform. A core barrel is often used to cut through the rocky sea floor during drilling.
      By: eyeidea
      An offshore oil platform. A core barrel is often used to cut through the rocky sea floor during drilling.