As shaped polycrystalline diamond compact (PDC) cutter geometries become more prevalent across the industry, this paper statistically reviews field testing of novel shaped PDC cutters in a variety of challenging applications. Firstly, the paper identifies the improvement in efficiency when compared with conventional PDC cutter geometries. Secondly, it confirms the reliability and robustness of the aforementioned shaped cutter geometries.
After several years of field testing shaped PDC cutter geometries, the question of how they hold up against conventional cylinder-shaped cutters remains unanswered. This study looks at drill bits that have the same overall design; however, each bit has different shape configurations that are deployed in a range of hole sizes and drilling applications. Data was collected from more than 100 runs and included advanced dull evaluation techniques, data mining, and comparative analyses. During data collation and interpretation, several statistical methods were used to improve the accuracy of comparisons and observing trends.
These results are statistically profound, they show that in the majority of cases, shaped cutter geometries enhance drilling efficiency either in line or beyond laboratory testing. For a comparable parameter envelop, an improvement of between 20-40% in rate of penetration (ROP) was observed in various hole sizes, particularly in carbonates through Arabian Gulf reservoir formations. The reliability assessment, which speaks to the number of runs per serial number, has shown an improvement over conventional type cutters and in some cases reaching six re-runs. Cutter robustness was deduced by comparing the average interval drilled, while also reviewing the overall dull in context to the typical dull condition.
When considering all three metrics over the large data set, it can be concluded that shaped cutters have, at a minimum, equivalency in both robustness and reliability, but, more importantly, bring an efficiency advantage over their legacy generation of PDC cutters. When considering the deployment of shaped cutter technology, the study has highlighted a significant flexibility in vertical, directional, and extended lateral applications from hard and abrasive rock to highly interbedded formations. Overall, shaped cutter efficiency and robustness have been validated in the laboratory and now proven to bring greater change in drilling performance and reliability.
This paper pushes beyond the claims within laboratory testing and statistically proves the robustness, reliability, and efficiency of shaped cutter geometries within the drill bit market. Not only is their usage growth now statistically proven, but a methodology has been developed to comparatively assess this technology during field testing. As PDC shaped cutter technology continues to grow, it is important to define its limitation along with determining where to deploy its strengths to obtain peak drilling performance.
