Continuous Improvement Wins In 190°C Extremes in the North Sea

A Four-Well Success Story

In the North Sea exists one of the most technically demanding environments for drilling. Noted by it’s high-pressure, high-temperature characteristics, this HPHT reservoir has temperatures reaching 190°C (375°F) that require measured pressure drilling (MPD) to complete.  To tackle this challenge, the Ulterra team partnered closely with a major operator to drive continuous innovation, speed of support, and close collaboration for the critical 12.25” section. Through a sequence of four wells (A-D), the collaboration showcased not just engineering skill, but the power of constant adaptability of bit design and drilling operation both.

Success Starts Early

Before any drilling, a customer led pre-design process was conducted to outline the main objectives for maximizing safety and risk mitigation downhole and establish a strategy for added challenge of MPD drilling. To achieve this, key bit design factors around gauge configuration and hydraulics were made. In less than 2 weeks, this resulted in a new fit-for-purpose 12.25” SPL616 bit design that was checked and sent to location.  

Well A – Establishing a Baseline

The first well with the new SPL616 began with a shorter 12.25” section which called for less directional work. The team drilled efficiently with strong ROP (rate of penetration) which showed early signs of promise. However, high vibration emerged during the run, that led to downhole tool failures. The SPL616 reached TD while drilling “blind”, and the section set the basis for future improvement.

Well B – Same Design, New Challenges

Building on lessons from the first well, the team reduced drilling parameters in anticipation of the vibration. Though stability improved slightly, tool failures persisted. Ultimately, the section required two runs, suffered lower ROP, and extended drilling time by five days. This underscored just how critical vibration control was, and the team collaborated to rethink the fundamental strategy needed.

Well C – A New Philosophy

Instead of incremental tweaks, the drilling team opted to build a new bit design specifically for smooth drilling and vibration mitigation. Working closely with the customer and operator, parameters were tuned specifically for MPD with a detailed guideline. The results spoke for themselves: record performance, highest ROP, and the longest section drilled-all while keeping vibration at manageable levels. Although tools still reached their endurance limits, the breakthrough was clear.

Well D – The Payoff

For the final well, the most complex of the sequence, the team refined parameters further based on prior experience. Despite added directional challenges, the section was drilled efficiently with excellent control-and, for the first time, zero tool failures.

Collaboration That Drove Results

This four-well journey highlights how data-driven iteration, proactive communication, and a focus on rapid support of customer goals deliver long-term success. The customer emphasized safety and minimizing risk-especially since tripping operations could take 4-5 days-and ultimately gained confidence and satisfaction with the final well’s performance.

Even in ultra-high-temperature conditions managed by active mud cooling systems, teamwork and adaptability proved key to achieving both performance and reliability.