Drilling the intermediate sections in the deep gas fields of Saudi Arabia is challenging because of a long, intricate geological sequence consisting of hard carbonates (limestone and dolomite) interbedded with anhydrite. Historically, the primary operator has attempted to drill the section using both roller cone tungsten carbide (TCI) and polycrystalline compact (PDC) technology. PDC bits provided better penetration rate and durability, as compared to TCI bits. However, several PDC bits were required to drill the section, which increased the time needed for drilling and tripping at relatively deep intervals. The increased time exposes the well to risks when the hole is open for long intervals.
After further analyses and a systematic bit optimization process, three new PDC bit designs were created and used, which established new benchmarks in two of the deep gas fields. Meeting the objective of minimizing the number of bit trips by enhancing PDC bit performance and bit durability to drill longer intervals with a higher penetration rates required a new PDC bit technology in conjunction with optimized motor drive. To address the challenge, the operator, bit vendor, and other service companies worked together to develop an optimized solution to drill these sections.
The paper reviews the findings of the study in drilling the intermediate sections in two of the challenging deep gas fields. The study shows that PDC bit damage from encountering harder stringers was the primary impediment to achieving better performance. The impediment was overcome by implementing the new cutter technology and drilling simulation software to optimize the cutting structure design. The paper demonstrates the improvement in the deep gas fields in Saudi Arabia by comparing the performance of the most recent wells, in which the new technologies were implemented, to the earlier wells to illustrate the significant time and drilling cost reduction.