A Big Question for Digital Experts: What Is the Driller Trying To Do?

Abstract

Digital drilling experts spend a lot of time wondering “what was the driller thinking?” They are not being sarcastic. The question matters for those doing analysis or writing control algorithms because the significance of readings, such as level of torque at any moment, depends on what the driller is doing at the time. The interpretation is different if the rig is drilling, where significant torque is required, or reaming, where the resistance is likely minimal. “During the reaming process, a spike in torque indicates something altogether different from a similar spike while drilling. So, the machine must recognize at least these two states: drilling and reaming,” said Fred Florence, a drilling consultant. He is among a group of drilling automation advocates who put rig state on a short list of issues that must be addressed to make it possible to create drilling systems where multiple devices can read and react in sync to changing drilling conditions. In other words, they want to know the information in the driller’s head now, said Moray Laing, director of digital value well construction engineering for Halliburton. That means an automated device needs to know what the driller is doing and also be aware of concerns that could require quick reactions. “Unless we can give it the same situational awareness of a human, it will not be able to manage the complexity of the process,” said Darryl Fett, Total’s manager of research drilling and wells in Houston. Rig state differences also plague those trying to analyze drilling data who need to know what else was going on at the time. They struggle with multiwell data where different methods of calculating the rig state were used. Drillers leave a record of their work in drilling logs. But this after-the-fact report typically lacks the precise timing sought by digital analysts using high-frequency data to analyze events that can happen suddenly. “A data scientist working on drilling will tell you that one of their biggest pains is someone will ask them to build a model on lost circulation and here is some data,” Laing said. That analysis is not possible unless someone can offer details about when the fluid losses began, how long they lasted, and other bits of context that might matter, such as the drilling fluid properties at the time. When asked for a basic explanation of the rig state, Crispin Chatar, drilling subject matter expert for Schlumberger, compared it to bringing a car that has been overheating to the shop. The mechanic will ask what was happening when the trouble began. Did the trouble start while driving fast on a freeway? While stuck in traffic? Did it happen after the radiator fluid warning light went on? “Every single engineer who works in drilling optimization, drilling analytics, or any one of our remote operation centers uses rig state to quickly and clearly understand what is going on at the well-site in terms of drilling operations or what the system might be seeing downhole,” Chatar said.