The non-magnetic drill collar is meticulously crafted from a specialized low carbon, high chromium manganese alloy steel, subjected to a stringent refining process that carefully balances its chemical composition and forging techniques. This meticulous approach results in a product with exceptional mechanical properties, including low permeability, high strength, resistance to intergranular corrosion cracking, and outstanding abrasion resistance. When exposed to a magnetic field intensity of 1 x 105/4 PI A/m, the relative permeability of the non-magnetic collar remains below 1.010 R.
At intervals of 100mm along the collar, the magnetic field gradient strength is maintained at a level equal to or less than 0.05 mu T. This design feature ensures that during borehole trajectory measurements, the impact of magnetic drilling tools is minimized, allowing for accurate measurement of the borehole's geomagnetic field without interference.
By employing non-magnetic drill collars, a controlled non-magnetic environment is established around magnetic measurement instruments. This environment enables the acquisition of precise data on the earth's magnetic field without distortions caused by external magnetic influences. The inclusion of a significant number of non-magnetic drill collar products in the API standard since 1990 underscores the industry's recognition of their importance. Additionally, China has developed its own standard, SY/T 5145-86, based on international product samples and specifications.
The use of rolled or forged AISI4145H Cr-Mo alloy steel plays a pivotal role in maintaining control over the chemical components and trace elements of the drill collar. Positioned at the bottom of the drill string, the drill collar serves as a critical component of the lower drill assembly. Its notable features include a substantial wall thickness, typically ranging from 38mm to 53mm, equivalent to 4 to 6 times the thickness of the drill pipe. This robust construction provides the drill collar with increased gravity and stiffness, essential for maintaining stability and control during drilling operations.
Vigor's non magnetic drill collars are manufactured in strict accordance with API Spec.7-1, 5DP and NS-1 standards, and Vigor will also give our customers photo and video feedback during production and transportation to ensure that all goods are under control. If you are interested in downhole drilling tools or other products for the oil and gas industry, please do not hesitate to contact us.
