Fit-For-Purpose Roller Cone Bit Technology to Improve Performance in Highly Interbedded Carbonates and Anhydrite Application in Southeast Kuwait

Abstract

A 16-in. section of a well, located in the Great Burgan field of southeastern Kuwait, presents multiple drilling challenges. The section is approximately 4,000 to 5,000 ft long and is drilled through a highly interbedded formation that consists of carbonate, shale, and anhydrite. The carbonate typically generates impact damage, causing high levels of thermal degradation that affect the gauge inserts. In addition, lost circulation is a hazard commonly encountered during this application. The drilling of this section requires control of drilling parameters, specifically the flow rate. Failure to maintain sufficient flow rate results in poor cuttings transmission and insufficient cutting structure cooling that can create further performance complications. The challenge in this application is to drill the entire section with one bit run at a maximum rate of penetration (ROP). This paper describes a new tungsten carbide insert (TCI) drill bit design that helped to improve the drilling performance in this challenging section in different well profiles. This paper provides a detailed study of the challenging 16-in. section in Kuwait and discusses potential issues, problems, and solutions associated with the use of the new advanced roller cone design.