Introducing New 22" PDC Bit for Drilling Complex Shallow Sections in a Giant Field in the Middle East

Abstract

Abstract Drilling a 22" section across interbedded, high-impact, and abrasive formations has historically been challenging in giant fields in the Middle East. The section typically ranges from 3,000 ft to 4,000 ft long and requires three to four runs to reach the casing point with conventional TCI bits. This paper covers the introduction of a new 22" PDC bit design run on rotary assembly, which has spectacularly improved the drilling performance over the conventional tricone bits. The introduction of this new 22" PDC bit design followed a comprehensive engineering approach. Starting with the simulation of rock properties such as compressive strength, abrasiveness, and impact, a fit-for-purpose bit design was manufactured to address the needed cutting structure, number of blades, and depth of cut for the section. The downhole drilling dynamics were also thoroughly analyzed, and the bottom hole assembly configuration was revisited to match up with the new bit structure. Within the dedicated continuous improvement workflow set by the service company, the bit pattern was further optimized after the initial field trials. After an in-depth analysis of the various formation properties and their impact on bit life, the 22" section was divided into two target runs. The upper part has high-impact and interbedded layers, and the lower part has high abrasiveness and formation compressive strength. In the upper part, the TCI bits had previously shown relatively good performance with acceptable ROP, while the PDC bits experienced damage to their cutting structure. As the impacts were lower in the bottom part, the PDC bit design was selected for the second run to the casing point, which resulted in significantly higher ROP and a longer lifetime than the TCI runs. The 2-bit strategy, spudding the section with the TCI bit and completing it with the PDC bit on rotary assembly, translated into a significant improvement of ROP by 32%. In addition to saving rig time, the overall number of bit runs was reduced by 29%, resulting in cost savings by using fewer bits. Drilling the section in two runs has now become the norm, and this winning strategy was adopted as the new standard for drilling the 22" hole section. The introduction of the 22" PDC bit on rotary drive returned excellent results and record-breaking ROP performance. While the 22" PDC cost might seem prohibitive, the substantial rig time savings proved this solution to be very economical. Further development of this initiative to other basins in the Middle East or elsewhere will mutually benefit both the operator and service company.