SLB achieved drilling objectives after the well design changed to one with a narrow dogleg severity (DLS) window close to the technical limit of well completion equipment.

Unexpected geology forces change in drilling plan

The original plan for a well being drilled for Karachaganak Petroleum Operating (KPO B.V.) in western Kazakhstan required kicking off and building a curve with a 6.5°/30-m dogleg in the 8½-in section and then drilling the lateral 6-in section. However, because of high geological uncertainty, the top of the reservoir was found deeper than expected, requiring the dogleg in the 8½-in section to be increased to 10°/30 m. The well needed to be replanned to eliminate the risk of tool damage and issues running casing. The new plan called for a 7.5°/30-m dogleg in the 8½-in section and 12°/30 m in the 6-in section. The DLS limit for well completion equipment was called by KPO as 15°/30 m. The challenge was to stay in the very narrow DLS window to achieve the planned DLS without exceeding tool specifications and to stay within the AFE.

PowerDrive Archer RSS recommended to achieve directional requirements

SLB drilled replanned trajectory with fit-for-purpose BHAs that include PowerDrive Archer™ high build rate rotary steerable system and the ImPulse™ integrated MWD platform.

We successfully delivered the well with highest directional complexity in the field ahead of AFE.

SLB and KPO worked together to identify options to save the well. They formulated a new drilling plan that eliminated the risk of twistoff and issues with running casing. From previous experience, it was recognized that the PowerDrive Archer high build rate RSS could deliver the redesigned well profile. To log the severe dogleg sections of the new well plan, SLB suggested running the ImPulse platform. With the capability to log doglegs as severe as 15°/30 m while improving drilling performance, the new BHA design would help KPO achieve its objectives.

Drilling system delivers well ahead of AFE, sets multiple performance records

The BHAs incorporating the PowerDrive Archer RSS successfully drilled the well to TD with 100% shoe-to-shoe performance. The well was delivered ahead of AFE and was one of the top three wells in the field in terms of on-bottom ROP and total well construction time. The PowerDrive Archer 475 RSS delivered a SLB footage record for the system in the 6-in section and a field record for the longest 12¼-in and 6-in sections in one run. The 7-in liner in the 8½-in section and the completion in the 6-in section were run without any issues. The trajectory, which was the most directionally complex in the field with a directional difficulty index of 6, was delivered according to plan, with actual tortuosity only 3% higher than planned.