An Innovative Method for PDC Bit Design Enhances Stability and Durability Without Deteriorating ROP: Case Studies in Challenging Swamp and Offshore Wells, East Kalimantan, Indonesia

Abstract In East Kalimantan offshore drilling operations, Polycrystalline Diamond Compact (PDC) drill bits featuring six-bladed, 16-mm cutters have been predominately used in an 8½-in. hole section. However, a standard S-type well for an 8½-in. hole section in the Handil Field with long interval drilling and deep vertical depth out presents a challenge of high stick/slip vibration. Meanwhile, in the Jempang Field, drilling through various formations consisting of sandstone, claystone, thick limestone, and hard shale using motor assembly could result in bit damage and slow rate of penetration (ROP). The operator and bit service company used a new approach in the bit selection process to seek a new PDC design and technology that enables drilling in a single run to target depth (TD) with improved durability and stability while achieving high penetration rates. A PDC with seven-bladed 16-mm cutters with the latest cutter-shaped technology was proposed to improve bit durability and drill the entire section in one run at a higher ROP. A new bit design software, coupled with the recommendation for an optimal PDC cutter distribution structure, ensures the bit will improve stability. The result shows a new design with seven-bladed, 16-mm cutters achieved one run to TD and set the fastest ROP compared to previous cases with six-bladed, 16-mm cutters in both the Handil Field and the Jempang Field. The bit also came out of the well in excellent condition or much better dull condition. In addition, with the combination of this new approach in PDC design and optimal parameters, the stick/slip issue could also be minimized in this first trial in the Handil Field. This new approach of using a new seven-bladed PDC design with 16-mm cutters that incorporate superior PDC cutter technology and shape has delivered a step change in bit selection to achieve improved durability without compromising on ROP for challenging offshore drilling operations.