To increase output and efficiency of traditional oil-lubricated pumps, both horizontal and vertical, manufacturers are seeking bearing technologies capable of a higher load capacity without affecting bearing life. At the same time, pump manufacturers want bearings that have lower power loss to reduce the expense of operating the pump and the size and associated costs of the oil lubrication systems.
The Hidrax™ HT thrust bearing can address the increased ESP temperatures in SAGD wells, which are reported as high as 270°C (518°F).
Technological advances in steam-assisted gravity drainage (SAGD) are causing electric submersible pumps (ESPs) to operate in higher temperatures and at higher speeds. The high temperatures place increased demands on the thrust bearings in the motor and seal/protector sections of the string. Given the high cost associated with a well’s downtime, equipment is expected to continue to perform even in difficult conditions, such as contamination. As a result, there is an increased demand for bearings that can operate with lubricants contaminated by abrasive materials.
In the subsea pump industry, multiphase pumps introduce a wide range of fluids and fluid viscosities, as well as abrasives, to the equipment operating conditions. These conditions drive bearing advances that increase durability and load capacity. Furthermore, subsea pump manufacturers place a premium on increased operating life and operating safety margin, due to the cost of repairing a subsea pump.
Bearing technologies keep pace with demands
To meet industry demands, a significant investment in research and testing is being made to evaluate the durability and performance margins of existing and new bearing designs, including a plethora of material options. Each bearing material and mechanical design is evaluated for its ability to accommodate higher temperatures, higher loads, higher speeds, abrasives and a variety of fluids, such as light and heavy oils, high temperature oils, water and multiphase, including gases.
For traditional oil-lubricated pumps, new designs, such as novel pad geometries and new materials, such as polymers and metallics, provide higher load capacity. In horizontal pumps, an increase in load capacity may allow for a reduction in losses associated with inefficiencies of thrust balancing. Alternatively, the ability of an advanced bearing to handle a higher unit load allows the manufacturer to use a smaller bearing for a given load, resulting in lower power loss and increased pump efficiency. For vertical pumps, not only is the required thrust bearing size being reduced for improved efficiency, but more efficient housing designs and cooling coils are further reducing power loss and the space requirements of self-contained bearing assemblies. For both horizontal and vertical pumps, if power loss reduction or a smaller bearing is not desired, the higher load capacity of an advanced bearing provides higher safety margins for a given size and load.
New ceramic/cermet bearings, like the Hidrax™ HT thrust bearing from Waukesha Bearings, can address the increased ESP temperatures in SAGD wells, which are reported as high as 270°C (518°F). The Hidrax HT ceramic/cermet bearing surfaces retain their strength, hardness and load capacity in oil bath temperatures in excess of 300°C (572°F). These capabilities exceed the limits of traditional ESP bearing materials, such as babbitt-lined bearings, as well as more recent ESP bearing material developments, such as polymer. In addition to handling high temperatures of the SAGD environment, the Hidrax HT bearing has the potential to handle abrasives in the event a sealing component fails.
For the subsea market, ceramic/cermet bearings are handling higher loads and higher temperatures, as well as low viscosity fluids and abrasives. Advanced bearing designs for the subsea market also offer superior load leveling and pivot mechanisms that eliminate the possibility of pivot wear and leveling link binding while providing improved load-equalizing capabilities over an extended pump life. In combination, these engineering advances ensure a robust design for subsea pumps.
When seeking a bearing solution, pump manufacturers and operators need to look to advanced materials and technology-leading designs that can keep pace with the other technological advances in the industry to extend pump operating life, reduce ancillary equipment size, and improve production and efficiency. The ideal bearing supplier is a partner that can serve as a reliable, consistent resource for product and technical information – ensuring the quality of the bearings for current and future application demands.
About the Author
Barry J. Blair is Chief Engineer at Waukesha Bearings, headquartered in Pewaukee, Wis., USA. Blair has responsibilities for fluid film bearing research & development activities, including new products and the refinement of bearing design tools and methods.