Abstract

Optimised drilling performance requires matching the right drill bit technology to an application, which can be an engineering challenge. Hybrid bits provide versatility in drill bit selection that was previously not possible with conventional drill bit technology, allowing for a broader range of applications. This paper details the results of a case study where polycrystalline diamond compact (PDC), tungsten carbide insert (TCI) and hybrid bits were tested in the same application in an attempt to improve drilling performance.

Each drill bit type has its strengths and weaknesses, and is therefore suitably matched for specific applications. Sometimes, a specific technology matches well to the application, and it is the ideal solution; however, there are many cases where the ideal drill bit type isn't so clear. Hybrid drill bit technologies produced a new generation of bits. These bits reduce the difference between specific bit technologies, enabling them to outperform either type in demanding applications that require strengths from each technology to drill successfully.

A non-homogeneous carbonate formation that was prone to causing impact damage challenged conventional drill bit technologies. The 12.25–in. hole section was drilled vertically on a rotary bottom hole assembly (BHA). Initial trials with PDC bits showed that the bits suffered significant impact damage, preventing them from completing the section or reducing their drilling capacity so the rate of penetration (ROP) dropped below TCI performance. The TCI bits drilled relatively slowly, and although they were more durable, they also suffered impact damage.

Hybrid bits were tested on this project to leverage the benefits of each technology and improve drilling performance in this section. This hybrid technology achieved outstanding results in the South Ratqa field. In multiple deployments the hybrid drill bit doubled the ROP compared to conventional technologies. The benchmark performance reached by the hybrid drill bit was triple the ROP of conventional technology. The trial saved the operator up to 3.5 drilling days and more than 70% of the drilling cost for this section.

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