Publications

Polycrystalline Diamond Compact (PDC) bits with six-bladed, 16-mm cutters have dominated the 8½-in. hole section in swamp drilling operations to produce fast drilling. However, a typical S-type trajectory with long interval drilling causes a high stick/slip issue and could potentially lead to a drop in the rate of penetration (ROP) in the last 300 m prior to reaching the total depth (TD) section. In addition, the lithology with a very consistent interbedded soft-hard formation could also potentially result in bit damage.

The operator and bit service company utilized a new approach in the bit design process to seek a new PDC technology that enables drilling in a single run to TD with improved durability while achieving high penetration rates. A PDC bit with seven-bladed, 16-mm cutters and the latest cutter-shaped technology was proposed to improve bit durability and drill the entire 8½-in. section in one run at a higher ROP. A new bit design software coupled with recommending an optimal PDC cutter distribution structure also ensures improved bit stability.

The results show that a new bit design achieved one run to TD for a single 8½-in. bit and set the fastest ROP compared to previous cases with 78 m/hr. The bit also came out of the well in excellent condition with minimal normal wear (1-1-WT). In addition, with the combination of this new approach in PDC design and bottomhole hole assembly configuration, the stick/slip issue could also be minimized on this first trial in the S-type trajectory.

This new approach of using a seven-bladed PDC design with 16-mm cutters that incorporates superior PDC cutter technology and shape has opened a new step change in a bit selection to achieve improved durability without compromising ROP for a challenging S-type well trajectory.