What’s Different About These Drill Bits? How a Little Change Can Be Made To Matter

Abstract

There is not a big difference between those two drill bits. Both have fixed cutters and show some wear. If they look small, that is perceptive. They were used on the automated drilling rigs, which are the scale of machine tools, built by student teams for the Drillbotics competition. The one on the top was designed by the team from the Norwegian University of Science and Technology (NTNU), which was the first to design its own fixed-cutter bit in the competition put on by SPE’s Drilling Systems Automation Technical Section (DSATS). The difference is in the polycrystalline diamond cutters (PDC), and it is not a big one. The ones on the student-designed bit (top) have a lower profile than the one (bottom) provided to all the competitors for free by Baker Hughes, a GE company. Varying the cutter size and angle to change how much rock a bit breaks off per rotation are common design options. When John Macpherson, a senior technical advisor for Baker Hughes and a former DSATS chair, saw it, he said: “It looks like a normal PDC bit.” What made that small difference worth noting are the things the NTNU team did to turn it into a significant advantage. “Even though the designed drilling bit may look like the most important element, it was a combination of a number of factors that allowed them to enlarge the (performance) envelope and drill much faster,” said Alexey Pavlov, a professor of petroleum cybernetics at NTNU who was the faculty advisor on the project. The challenge faced by these teams building something that looks like drilling in miniature is a fundamental one facing engineers building and running drilling machines at a time when the word drilling is married to the word system. Performance will vary based on how well the parts, and people in different disciplines, work together. “Those in drilling need to understand these are systems, not just mechanical devices,” Macpherson said. “We originally started here building mechanical tools with a mechanical engineering group. Then we brought in electronics, software, physics modeling and so on, and now we have a drilling systems engineering group.” That cooperative, multidisciplinary approach required by Drillbotics “very much mirrors (and perhaps leads) real-world approaches,” he said. That complicated stew of the variables attracted Sebastian Knoop, the NTNU student who was the first to volunteer for the university’s Drillbotics team, which was one of their Master’s project options. “Drillbotics was the one I found really interesting. It was a competition. That is the one that lit me up. The mix of drilling, robotics, and automation got me into it,” he said, adding, “I was the first one on the team, then some of my friends got in it as well.” Significantly, they also recruited a “guy not from the same petroleum engineering gang as the rest of us,” he said. That recruit, Mikkel Leite Arnø, majored in industrial cybernetics and provided critical robotics expertise. They were heeding the advice from the Drillbotics judges to the 2017 NTNU team to “try to establish a multidiscipline team next year.”