Introduction to oil drill collars
Oil drill collars are an important part of the drill string, located at the bottom of the drill string and connected to the drill bit. It is a seamless steel pipe with a thicker wall and a larger unit length weight, usually made of high-strength steel.
- Spiral drill collar:
Three right-hand spiral grooves are machining on the outer cylindrical surface of the round drill collar to reduce the contact area. With the well wall and effectively prevent differential pressure from sticking the drill. Its characteristic is that it can reduce the contact area with the well wall to a minimum. And is particularly suitable for drilling environments where differential pressure is prone to sticking the drill.
Mainly used for monitoring during oil drilling. The structure is the same as that of the integral drill collar, made of N1310 low-carbon alloy steel, and forged after strict chemical composition analysis. The material has good low magnetic permeability and machinability. Which can ensure that the hardness, toughness, impact value and corrosion resistance meet the standards. Often using in drilling operations with special requirements for the magnetic field environment. Such as situations where precise measurement of the magnetic field is requiring in geological exploration.
- Integral drill collar:
It is a smooth thick-walled round tube with connecting threads at both ends. It has a large gravity and rigidity, can apply drilling pressure to the drill bit, ensure the necessary strength under compression conditions, reduce the vibration, swing and jump of the drill bit. Make the drill bit work more smoothly, and control the well inclination. The suitable for use in complex working conditions such as deep wells and high-pressure jet drilling.
At present, a series of drill collar products of various specifications within a length of 12m have been developing to meet different drilling needs. In practical applications, according to specific drilling conditions and requirements. Choosing the right type of drill collar is of great significance to improving drilling efficiency and safety.
Manufacturing materials of Oil Drill Collar
1. AISI4145H chrome-molybdenum alloy steel
AISI4145H chrome-molybdenum alloy steel is one of the commonly using materials for manufacturing oil drill collars. Its chemical composition includes carbon, manganese, silicon, chromium, molybdenum and other elements. This steel has excellent strength and wear resistance, with a tensile strength usually between 1300 MPa and 1500 MPa. And a yield strength of about 930 MPa to 1080 MPa. At the same time, it also has good impact resistance and toughness. And can withstand heavy loads and severe vibrations in complex drilling environments.
In terms of heat treatment, through homogenization heating, quenching and tempering processes, AISI4145H chrome-molybdenum alloy steel can achieve the required hardness and strength. And its hardness is usually 302-363 HB (Brinell hardness) or 30-36 HRC (Rockwell hardness).
2. N1310 low carbon alloy steel
N1310 low carbon alloy steel is often using to manufacture non-magnetic drill collars. This material has undergone rigorous chemical composition analysis and forging processes. So has good low magnetic permeability. Which can meet the special requirements for the magnetic field environment during oil drilling.
Therefore mechanical properties of N1310 low carbon alloy steel are also excellent, with a yield strength of usually ≥825 MPa. A tensile strength of ≥930 MPa, an elongation of ≥20%, and a Charpy impact energy of ≥100 J. In addition, it also has good corrosion resistance and hardness, which can ensure stability and reliability in drilling operations.
However characteristics of these materials enable them to play their respective advantages, in the manufacture of oil drill collars. Thereby improving the performance of drill collars and adapting to different drilling conditions and requirements.
