شرح العمدان واوزانها وانواعها-Drill Collar Weights, Size, Specs, Definition &Types

Drill- collar( D/ C) are large periphery-small drag sword pipes that ret
ain a great weight and great stiffness. While designing BHA, drilling masterminds place D Cs above the Drilling Bit as D/ Cs are the predominant element of the Drilling BHA. To elect the proper D C you'll have to have all information about Drill collar Weights, Size, Specs, description, lengths & Types. This composition is a part of the series explaining Drilling Bottom Hole Assembly factors, Types & medium

What is the functions of Drill Collars:

• give weight on the bit( WOB)
• Minimize bit stability problems from climate, wobbling and jumping
• Minimize directional control problems by furnishing stiffness to the BHA.
• Keep the drill string in pressure, so that it'll reduce bending stresses and failures due to fatigue

Drill Collar Thread Types

Since the D/ C have such a large wall consistence Tool Joints aren't necessary and the connection vestments can be machined directly onto the body of the collar. The weakest point in the D/ Cs is the connection and thus the correct makeup necklace must be applied to help failure. The external face of a regular collar is round( slick), although other biographies are available.


The D/ C number( column 1) consists of two corridor separated by a hyphen.

• The first part is the connection number in the NC style.
• The alternate part, conforming of 2( or 3) integers, indicates the Drill Collar outside periphery in units and tenths of elevation.

The connections shown in hiatuses in column 1 aren't a part of the D/ C number; they indicateinter-changeability of D/ Cs made with the standard( NC) connections as shown.

If the connections shown in hiatuses in column 1 are made with the V-0.038 R thread, the connections and D/ Cs, are identical with those in the NC style.

D/ Cs with8-1/4 and9-1/2 elevation outside compasses are shown with6-5/8 and7-5/8 regulation connections since there are no NC connections in the recommended bending strength rate range.

The drill collar sizes listed in Table 1 were espoused in order to give a full range of DCs with bettered connections, as a relief for the DCs with the colorful connections specified in former editions of API Spec

Purchase orders for collars with the bettered connections should state the D/ C number or size and style, drag, and length. Purchase orders for collars with voluntary connections should state the outside periphery, drag, length, connection size and style, and bevel periphery.

Drill Collar Length

D/ C are typically supplied in Range 2 lengths( 30- 32 ft). The collars are manufactured from chrome- molybdenum amalgamation, which is completely heat- treated over the entire length. The drag of the collar is directly machined to insure a smooth, balanced gyration.

Drill Collar Weights & Size

D/ Cs are produced in a large range of sizes with colorful types of common connections. The Drill collar size and weights per bottom of a range of DC size are shown in Table 2. The weights that are quoted in Table 2 are the “ weight in the air ” of the D/ Cs. It's veritably important that proper care is taken when handling D/ Cs. The shoulders and vestments must be waxed with the correct lubricant( containing 40- 60 pulverized metallic zinc or lead).


Like drill pipe, collars are subordinated to stresses due to

• Buckling and bending forces
• Pressure
• climate
• Alternate contraction and pressure.

still, if duly made up, the shoulder/ shoulder connection will be sufficient to repel these stresses. The figure below shows how numbered connections should be named to give an effective seal and acceptable strength.

Drilling Collar Types

Anti-wall stick/ helical Drill Collar

When drilling through certain conformations the large periphery D Cs can come wedged pipe against the borehole( discriminational sticking). This is likely to be when the conformation is largely pervious, a large overbalance of slush pressure is being used and the well-conditioned largely deviates. One system of precluding this problem is to reduce the contact area of the collar against the wellbore. helical grooves can be cut into the face of the collar to reduce its face area.