Exploration • Drilling • Field Services
string. Tese applications require all types of rolling bearing, from basic application-specific bearings to complete ready-to-install systems.
Mud pumps and motors Mud pumps supply the drill rig with a constant flow of high-pressure mud, which is used as the drilling fluid. Tese positive displacement pumps operate at pressures of up to 10,000 psi, resulting in high radial loads at the typical bearing positions, including the crosshead bearings, eccentric bearings, crankshaft main bearings and drive shaft bearings. Schaeffler provides complete mud pump bearing sets for some of the most technically advanced mud pump designs. Tese bearing designs provide high capacity systems that are ideal for meeting the demands of ever increasing drill depths.
Sheaves and pulley systems Sheaves and pulleys are used in crown and travelling blocks, as well as for heave compensation systems, whose function is to decouple the dynamics of a floating drilling platform from those of the drilling tools. Reliability under high static and dynamic loads is therefore required in order to ensure maximum uptime under such an extreme range of drilling conditions.
extreme operating conditions. A complete range of full complement cylindrical bearings can also be specified.
Swivel, top drives Te top drive or swivel supports the drill string, whilst simultaneously acting as a rotating passageway that permits drilling mud to flow into the drill string. In addition, the top drive provides the torsional
force required to turn the drill string. Tis application requires high reliability bearings that also withstand the shock loads generated during the drilling process. Te solution here is to utilise high capacity bearings that are resistant to any possible spikes (peaks) in load. As well as providing these types of bearing, Schaeffler also encourages operators to work more closely with its application engineers in order to better understand the stresses developed during these periods of high load.
Rotary tables Te rotary table is the traditional method of providing the rotational force to turn the drill string. When the drilling process is interrupted, the rotary table can also function as a supporting device, carrying the entire weight of the drill string. Here, the bearing locations are exposed to high radial and axial loads. Due to these very demanding requirements, axial angular contact ball bearings are the preferred choice for the main bearing in rotary tables, in either single row designs or as three race assemblies.
Fig. 2. Schaeffler has designed bearings that maximise operation in a wide range of drilling conditions.
For these applications, Schaeffler provides traditional, high capacity, double row taper bearings in common oilfield sizes and in accordance with API 8C requirements. Banitic microstructure, hardened components provide a soft core with lower retained austenite levels to provide thermal stability under
Winches and draw works Te primary function of the draw works is to raise or lower the drill string and to provide the correct weight on bit (WOB). Te latest draw works and winches can also operate using Active Heave Compensation (AHC), which compensates for the movement of the ocean’s waves on the floating rig. Te resulting rapid load cycles require an extremely rigid system. Spherical roller bearings are the preferred solution for a hoist drum main bearing. Tese bearings compensate for any misalignments, whilst providing high load carrying capacity. Other bearing positions can be found in the motor and gearboxes that drive the hoisting drum. All of these bearings work together as a complete system to ensure reliable operation. ●
Dr Steve Lacey is Engineering Manager, Schaeffler (UK) Ltd, Minworth, Sutton Coldfield, West Midlands, UK.
www.schaeffler.co.uk
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