Case Study: Multiple Disciplines Come Together to Save 18 Days of Rig Time for BG Norge AS

Coordinated teamwork, from planning to drilling, increases ROP up to 147% offshore Norway

Challenge: Cost-effectively and efficiently drill two horizontal wells through a chalk section and potentially unstable shale formation offshore Norway.

Solution: Bring together multiple disciplines through the PTEC PetroTechnical Engineering Center for prejob planning, engineering, and drilling of the two-well project.

Result: Drilled both wells ahead of schedule, saving nearly 18 days of rig time, and increased ROP up to 147%.

Two-well subsea project offshore Norway

BG Norge AS was developing its Gaupe project—a two-well subsea project offshore Norway in the southern North Sea—and wanted a drilling approach that was both cost-effective and efficient. The project involved drilling through a chalk section in the overburden above the reservoir. After drilling through the overburden to the top of the reservoir, the challenge was to drill through an unstable shale formation into the interbedded reservoir and then drill horizontally to TD.

Schlumberger provided an integrated team approach, from planning and engineering to execution and drilling. Through the PTEC PetroTechnical Engineering Center, Schlumberger brought multiple disciplines together for prejob planning, engineering, and execution.

Integrated approach, from planning to execution

First the optimum bits and BHAs were selected for chalk drilling to reduce stick/slip and optimize ROP in both wells. The BHAs were then analyzed using i-DRILL engineered drilling system design to eliminate the risk and expense of trial and error on the rigs. Hydraulics were evaluated under simulated downhole conditions using VIRTUAL HYDRAULICS software to maximize drilling fluid performance and minimize overall costs. Finally, driller’s roadmaps were created using DrillMAP drilling planning and management tool. These drill maps were followed and drilling parameters were analyzed in real time to continually optimize ROP without compromising hole cleaning or well integrity. PERFORM Toolkit data optimization and analysis software was used to gather and analyze both static and real-time drilling data and avoid NPT.

Saved 18 days of rig time

In Gaupe South, the well was drilled vertically to the 12 1/4-in section, then kicked off from vertical to build through the chalk formation, and landed at 65° just above the reservoir. In Gaupe North, the well was drilled vertically to the 17 1/2-in section, kicked off in the section from vertical, and drilled through the negative vertical section to get displacement to complete the 12 1/4-in section through the chalk, landing at 65° just above the reservoir. Both wells were drilled through the shale to complete the build, land the well, and then drill the 8 1/2-in sections horizontally within the reservoir.

Drill maps were monitored closely in real time by both offshore crews and the onshore PERFORM engineer in BG’s offices.

With multidiscipline planning, evaluation, and execution, both wells were drilled ahead of schedule, beating BG’s P10 targets and saving nearly 18 days of rig time over the two-well project. The Gaupe South well broke an existing Rushmore drilling record for subsea development wells. Increases in ROP were 146% in the 17 1/2-in section, 37% in the 12 1/4-in section, and 147% in the 8 1/2-in sections.

Download: Multiple Disciplines Come Together to Save 18 Days of Rig Time for BG Norge AS (0.99 MB PDF)

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"When we planned Gaupe, we were aware of the new opportunities that existed within Schlumberger. We had the opportunity to do something new, something unique and raise the bar on how wells could be delivered. The drilling performance delivered by Schlumberger was a major contribution to the success of the Gaupe development project and BG Norge’s first oil and gas production."
Allan Ritchie
Senior Drilling Engineer
BG Norge

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