The operator wanted an ERD well placed within a tight geological target. With conventional measurements while drilling (MWD) and conventional gyro while drilling (GWD), the effective target size was extremely difficult to drill with accuracy.
GyroLink service was recommended for optimal well positioning with faster survey times. The technology features three solid-state gyros, which work with WellDefined™ automated survey solutions to tighten the ellipse of uncertainty (EOU) by taking advantage of the additional MWD survey data from TruLink™ definitive dynamic survey-while-drilling service. Despite the geological challenges in the reservoir, the driller’s target was achieved with neither deviations nor sidetracks.
The EOU was significantly smaller with the GyroLink service than with conventional technologies. Only the GyroLink service delivered a positive driller’s target, which signifies the geological target was greater than the EOU. Both conventional MWD and conventional gyroscopic measurements resulted in negative driller’s targets, which indicates the geological target was less than the EOU. Thus, the accurate placement of the well was nearly impossible without the use of the GyroLink service.
| Technologies Deployed and Corresponding EOUs and Driller’s Targets | ||
| Survey service | Semimajor lateral EOU, ft | Driller’s target, ft |
| Conventional MWD and all corrections | 238 | –116 |
| Conventional GWD | 209 | –60 |
| GyroLink service | 156 | 48 |
Survey times were also a factor. Additional surveys were required because range-3 drillpipe was used, which means the survey frequency would be greater than the assumptions in the conventional MWD error model. To expedite these surveys, the operator deployed the TruLink service, which delivered surveys as often as every 2 minutes to improve operation performance. These surveys were delivered in real time and required no extra rig time, saving the operator the associated costs and carbon footprint.
In the 12¼-in section of the well, SLB services were supported by the Performance Live™ digitally connected service to ensure the improved survey error model was properly reflected in the definitive survey listing of the well.
With improved drilling performance, the operator achieved the longest and near-impossible well in the UK section of the North Sea, gaining 1 day of early production, losing no time waiting on surveys, and optimizing placement of future wells in the reservoir.
