Abstract

Drill bit performance has a direct connection with the economics of drilling a well. While there have been impressive advances in both PDC and roller-cone drill bits over the previous decades, the rate of improvement has declined in recent years. New drill bit technologies are required in order to regain the pace of performance improvement, especially in large hole sizes.

Traditional development cycles for novel drill bit technologies tend to be lengthy, with new products reaching commercialization after close to a decade, or more, of R&D. Critical new technologies are typically only developed by the largest oilfield service companies in the industry, which contributes to the pace of development. In order to deliver enhanced performance to the industry in months instead of years, an entirely new approach is required. As a response to this situation, a unique process has been created and implemented which has allowed a brand new type of oilfield drill bit to be commercialized within one year of the initial concept.

This paper will discuss the performance of a new type of oilfield drill bit that has proven to reduce operating costs in large hole diameter intervals. This new type of drill bit has a novel hybrid cutting structure with both rotating, gouging inserts and shearing PDC cutters. This unique cutting mechanism has demonstrated improved performance compared to both PDC and roller-cone drill bits in hundreds of applications. The challenges associated with increasing drilling performance in large hole sizes are significantly different from intermediate and production intervals, and this paper will detail how those challenges are met by the new cutting structure. Worldwide, roller-cone bits have maintained a relatively large market share of sections that are 12-1/4″ diameter and larger due to their toughness, steerability and smooth drilling behavior compared to PDC bits. However, roller-cone bit performance is still limited by the durability of bearings, seals and teeth / inserts. The new hybrid gouging / shearing cutting mechanism provides similar performance benefits to roller-cone bits, such as excellent steerability, while providing durability superior to PDC bits.

The introduction of gouging cutting structures into fixed cutter drill bits is an active area of R&D in the industry. For more than a century, drill bits have failed rock via crushing (roller-cone bits), grinding or plowing (diamond impregnated / natural diamond bits), or shearing (PDC bits). The gouging mechanism displays unique characteristics compared to conventional methods, and initially appears to be more suitable to many drilling environments.

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