On August 31, 2026, CNPC Western Drilling completed the UDG-1P well in Uzbekistan at 7,540 m, setting a new Central Asia drilling depth record. The well was drilled in 420 days under high-temperature, high-pressure and complex geological conditions. In such tough environment, the material is required to have high compactness, high strength, excellent corrosion resistance, and non-magnetic properties, as well as the ability to withstand high temperatures and high pressures. And if we apply non-magnetic drill collar in the drilling, how it works?
The NMDC is positioned in the BHA around the MWD tool and above the bit. Inside this zone, magnetometers read the true Earth's field vector. The MWD system then calculates inclination and azimuth, allowing precise steering. Without NMDC, magnetic interference from steel components can make surveys unreliable, especially in deep wells where small errors accumulate over thousands of meters.
At depth, high temperature and pressure affect material performance. NMDC alloys must maintain low magnetic permeability and mechanical strength at elevated temperatures. They also need high-torque connections, thick walls, and fatigue resistance to withstand heavy drill string loads. Corrosion resistance is required for exposure to oil-based fluids, brines, H2S, and CO2.
Mechanically, NMDC also adds weight and stiffness to the BHA, helping control bit load and well trajectory. But its primary function is magnetic transparency-keeping the MWD compass accurate in extreme downhole conditions.
In ultra-deep wells, reliable NMDC performance directly supports wellbore accuracy, collision avoidance, and drilling efficiency.
