The positive economic impact of a metal bearing seal on roller cone bits used in conjunction with downhole motors and steerable systems in a Abu Dhabi Onshore fields has been dramatic. The metal seal has proven its ability to extend seal/bearing life of roller cone bits significantly (one million bit revolutions or 1000 krevs without seal failure are common) relative to elastomer sealed bits. This bearing, along with an improved cutting structure, has resulted in more on bottom drilling time.

The metal seal technology is especially useful when used on steerable motor assemblies. The bits have been successfully applied to kick-off from vertical and generally drill the 8-1/2" build section between 8°-14°/100 ft to the landing point at 90°, through interbedded formations ranging from soft shales to medium-hard limestones. Unconfined Compressive Strength varies from 5,000 psi to 15,000 psi. As the bits were applied throughout the region, the manufacturer used step changes to improve the cutting structure and hydraulics to further enhance bit performance and durability.

The authors will document significant cost reduction through improved bit performance in high-speed directional applications for the new metal bearing seal design compared to the best performing elastomer sealed bits. The study will include data from 386 bit runs totaling over 232,734 feet and 15,821 drilling hours documenting a decrease of 42% in cost per foot or a saving of US$3,836,400 over a three year period between April 1998 - March 2001.

You can access this article if you purchase or spend a download.