What is drill collar used for?

Drill collars are thick-walled tubulars that are used at the bottom of the drill string (see Figure 4-1). Their principal purpose in the drill string is to provide the axial force needed to advance the drill bit (see Figure 2-2). When drilling a vertical borehole, the axial force is the weight of the drill collars.

What is a drill hole collar?

A drill collar is a device used at the lowest part of a drill string, an important part of the bottom hole assembly (BHA). It is always a very thick-walled tube to apply weight to the drill bit. Normally, a drill collar is threaded at both ends, male on one and female on the other.

How long is a drill collar?

The term drill collar derived from the short sub originally used to connect the bit to the drill pipe. Amodern drill collar is about 30 ft long, and the total length of the string of drill collars may range from about 100 to 700 ft or longer.

How heavy is drill pipe?

Drill Pipe Specifications

Pipe
Size OD, in.	Nominal Weight, lb/ft	Wall Thickness, in.
2-3/8	6.65	0.280
0.280
2-7/8	10.40	0.362

Why do we use heavy weight drill pipe?

Because it bends easily, heavy weight drill pipe simplifies directional control and minimizes connection fatigue problems that are common in high-angle or horizontal drilling. For extended reach and horizontal wells, high-strength heavy weight drill pipe is often used high in the hole to apply weight on the bit.

What is drill pipe made of?

Drill pipe, is hollow, thin-walled, steel or aluminium alloy piping that is used on drilling rigs. It is hollow to allow drilling fluid to be pumped down the hole through the bit and back up the annulus. It comes in a variety of sizes, strengths, and wall thicknesses, but is typically 27 to 32 feet in length (Range 2).

What is non magnetic drill collar?

Non-magnetic drill collar is a kind of drill collar made of high quality stainless steel in drilling tool. It is widely used in oil fields, but its failure rate is rising directly, and the oil well is safe.

What is the main difference between HWDP and drill collar?

The function of the HWDP is to provide a flexible transition between the drill collars and the drill pipe. This helps to reduce the number of fatigue failures seen directly above the BHA. A secondary use of HWDP is to add additional weight to the drill bit. HWDP is most often used as weight on bit in deviated wells.

What size is drill pipe?

The length of a drill pipe is typically Range 2 at 31 feet but can come in other lengths as well. A drill pipe is thick-walled and designed to hold its own weight in a drill string as the drill pipes are often run thousands of feet under the surface.