Drill Collars

E&M Supply Group offers new, used, re-manufactured, and stock drill collars. Drill collars comprise about one-third of all product sales for E&M Supply Group. The new drill collars we provide come from only reputable steel manufacturers and are made to outperform all industry requirements.

In their initial phase of manufacturing, drill collars are solid round bars of 4145 carbon steel. The bars are then quenched and tempered in a heat treatment process to attain the required metallic properties and hardness for drilling. Once heat treatment is complete, a hole is machined through the bar in a coring/honing process known as trepanning. This hole is better known as the ID or the inner diameter. After the trepanning is complete, the ends are machine threaded which makes the connections. E&M Supply Group’s main suppliers of completed drill collars or drill collar bars are Smith Services/Drilco, Timken Industries (USA), Vam Drilling (USA), Thyssen Krupp (France), Sumy Frunze (Ukraine), and Seah Besteel (S. Korea).

We also provide used drill collars, which are very common in the oilfield but are rarely found in good usable condition. This is because used collars have undergone so much thread repair that the overall length of the drill collar is shortened to a point that it is rendered unusable on most drilling rigs. At E&M Supply Group, much time and resources are devoted to finding these rare gems. Used drill collars that are still in good condition are a wise investment for any drilling contractor, as they can save a considerable amount of money.

Drill collars that have become too short can be re-manufactured through a process known as stub-welding. Stub-welding is achieved through a sub-arc welding procedure that has been widely used since the early 1980s. This welding procedure was first introduced in the manufacturing process of new heavy-weight drill pipe. There are only around 7 machine shops in the entire country that utilize this “tried and true” stub-welding procedure to re-manufacture drill collars, and the south Louisiana region is home to 4 of them. E&M Supply Group uses only these 4 machine shops to re-manufacture our drill collars.

E&M Supply Group also offers stock drill collars for sale. Stock collars are drill collars that have so much external wear that the outside diameter and weight of the drill collar are less than acceptable. Once this has occurred, certain size drill collars can be cut up and used as “stock” material to build subs, stabilizers, and various other specialty drilling tools.

About Drill Collars

Drill collars are extremely heavy-duty industrial tubular used to drill into the ground and are used in conjunction with drill pipe. While drill pipe makes up the majority length of a drill string, drill collars make up only a small amount. For example: a 10,000ft drill string may be comprised of 9,000ft of drill pipe, and only 500ft of drill collars. Much like drill pipe, drill collars are made in 31ft lengths and are screwed together vertically on the drilling rig. In contrast, to drill pipe, drill collars are thick-walled and heavy, with very limited flexibility. Drill collars are used at the bottom of the drill string, just above the drill bit. They are used mainly for weight on the drill bit but also work as a shock absorber to dampen the vibrations and impact forces caused by drilling. There are two main types of drill collars, slick or spiral grooved, however, both styles accomplish the same task. Spiral groove drill collars were introduced in more recent years and are thought to help prevent the drill string from getting stuck in the hole by allowing drilling debris and lubricant to pass more freely around the drill collar.

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