Operators in the current volatile oil and gas industry must optimise drilling performance and minimize well cost. Various drilling tools and methods have been implemented over the years to improve drilling efficiency and to reduce the non-productive time (NPT) while drilling through challenging formations. Many North Kuwait onshore wells are drilled with conventional drill bit technologies, such as tungsten carbide insert (TCI) and polycrystalline diamond compact (PDC) bits on either rotary or performance motor bottom hole assemblies (BHA). This paper discusses the breakthrough drilling performance of 16-in. hybrid drill bit technology on a performance motor BHA, delivering outstanding results and savings for the operator. The typical 16-in. vertical section ranges from 4000 ft. to 5000 ft., and contains limestone and sandstone with interbedded layers of shale and streaks of anhydrite with high variance in the unconfined compressive strength (UCS) across these formations.
The downhole environment is unsuitable for PDC bits due to impact damage from the variable UCS, and TCI bits provide unsatisfactory rates of penetration (ROP) requiring a new drilling approach for the application. Poor dull conditions combined with the long section led to low overall ROP, further indicating the need for a new class of bit.
The engineering process involved reviewing:
Current TCI and PDC cutting structure designs
Surface drilling parameters applied
Post-run dull analysis from current bit designs
Previous TCI and PDC bit design performance on rotary and motor BHA
Hybrid design performance on rotary BHA
A collaborative technical analysis identified key performance objectives to ensure a step change in section drilling. Hybrid drill bit technology was deployed on a performance motor BHA to enhance the ROP. The hybrid bit enhanced the ROP by 153% with a 52% reduction in cost per foot compared to the average TCI performance in this field, saving the operator 2.2 days and over $ 0.4 Million operational cost.
The hybrid drill bit design demonstrated its ability to serve as an alternative to conventional technologies and showed the potential for efficient drilling and reduction of NPT over multiple wells, assisting operators in the current cost-sensitive industry environment.