The beast of a challenge was solving for the curve. It requires an ability to access a form of ROP downhole for the tool to be able to measure a resulting dogleg severity (DLS) from its current steering parameters. Because the tool can measure its DLS downhole, it adjusts its own steering parameters each second downhole to get to the planned curve.
The benefits of replacing long surface control-loop time with an immediate response are distinct:
- It significantly reduces the number of downlinks needed to drill curves.
- Directional drillers can focus fully on drilling efficiency, resulting in faster ROP.
- Trajectories are smoother from more frequent but smaller adjustments made downhole.
- Decisions are now made by the tool downhole, so we get more consistency and repeatability in our trajectories.
What are you doing now?
It’s really what we’ve been doing. Our RSSs have been running with the autonomous downhole control system for 18 years all around the world. And our ABSSs do as well. Auto-curve, our latest autonomous module, was introduced in field testing over a year ago and we have drilled a total of 26,000 ft of curves with this autonomous mode. Field testing includes a wide variety of trajectories and formations in US land, the North Sea, and the Middle East. And these tests are case studies in the value downhole autonomy brings to our customers. Auto-curve reduces the downlinks needed to drill curves with an RSS or ABSS while increasing the overall drilling speed on these curves, delivering smoother boreholes in terms of low tortuosity.
We performed several runs on unconventional wells in the US, testing auto-curve using NeoSteer CL ABSS and PowerDrive Orbit G2 RSS. Curves in unconventional wells are crucial and a place where we wanted to bring efficiency and consistency. One of the published cases from the Permian Basin where very high shock and vibrations, high rpm, and drilling in the zone of exclusion—along the North–South line—make continuous while-drilling azimuth measurements downhole very difficult. The auto-curve from our autonomous downhole control system guided a PowerDrive Orbit G2 RSS while drilling seven curves on seven unconventional wells on a particular asset and comparing it with offset wells on the same asset. The curves required 42% fewer downlinks, and the on-bottom drilling speed increased by 39%.
In short, the autonomous downhole control system reduced downlinks, increased drilling speed, improved drilling efficiency, and minimized deviation from the plan with less tortuosity—all while helping to reduce associated emissions.
What differentiates autonomous directional drilling from other automation offerings?
Autonomous directional drilling focuses on the entire workflow and connects them along the way to ensure the best outcome. But the downhole automation is vital because it lies within the tool itself, downhole, having the ability to maintain verticality, tangents, laterals, and now curves without interaction (downlinks) from the surface. And to be clear, only Schlumberger offers functioning downhole autonomous drilling of 3D curves.
Despite the technology, the real difference is performance. By enabling the tool to make decisions downhole, we have the closest and fastest decision and reaction to data acquisition, therefore delivering the least tortuous well possible at the highest possible ROP. And soon, this difference in performance from a self-driving BHA will catapult efficiency and consistency in a way unobtainable by any exclusively surface-controlled system.