The industry is placing increased importance on drilling harder, faster, and longer, giving rise to the challenge of premature bit failure caused by drilling through transitions of varying rock strength. To address this issue, new strategies have emerged, such as using automatic drillers operating with a constant rate of penetration (ROP). In this study, a method was developed to analyze the effects of drilling through transitions on bit-cutting structures and construct an ideal drilling strategy to mitigate the forces overloading cutters using a detailed drilling model.
Testing Methodology
A physics-based drilling-simulation environment was used to study the effects of drilling through formation transitions on polycrystalline diamond compact (PDC) cutting structures. The environment can be used to model only a drill bit or a drill bit attached to a drilling assembly.
The environment allows a given PDC drill-bit design to be run through various rock formations or lithologies and can generate a set of outputs that characterize bit performance. First, rock lithologies and a drilling path must be set along with corresponding depths.
