Shell's goal was to land a horizontal well as close as possible to the top of the reservoir to limit risk of mud loss to ensure a smooth wellbore and avoid exits into the overburden shale formation.

SLB recommended GeoSphere™ reservoir mapping-while-drilling service for long-range detection of reservoir boundaries and optimal landing of the well.

The operator landed the well and placed the casing shoe at an 88º inclination within 3-ft [1-m] TVD of the top reservoir to line up the reservoir section and reduce the risk of mud loss. The GeoSphere service detected the reservoir top with drill bit 328-ft [100-m] MD away from intersection, leaving considerable room for steering the trajectory. The mapping-while-drilling service defined oil/water contact (OWC) to determine oil column greater than 33-ft [10-m], confirming the well’s production potential.

Land well in the pay zone, ensure integrity of wellbore

Shell wanted to mitigate risk while landing a well in the Draugen field of the North Sea. The target reservoir has exceptional porosity and permeability, and Shell aimed to raise the field recovery rate to more than 70%. However, the depth of the reservoir was uncertain due to several seismic realizations, different interpretations, and time-to-depth conversions. Shell needed an optimal landing of the well and a smooth wellbore throughout the reservoir section. This would maximize production in this attic oil scenario and decrease the chance of early water breakthrough. Another challenge was to avoid exits into the overburden shale, which would result in lost reservoir exposure and increase the risk of sidetracking.

Extend depth of investigation with reservoir mapping-while-drilling service

To meet its tight requirements and high recovery targets, Shell created a strategy to land its North Sea well using the GeoSphere reservoir mapping-while-drilling service, complemented by geoVISION™ imaging-while-drilling and adnVISION™ azimuthal density neutron services. The GeoSphere service provides real-time radial measurements extending the operators depth of investigaton to more than 100 ft [30 m] from the wellbore, giving them ample time to guide smoother wellbores for maximum contact from the beginning of the reservoir section.

Accurately detect reservoir boundaries to precisely land well

The GeoSphere service detected the reservoir 45-ft [15-m] TVD below the well path. At that time the drill bit was still 328-ft [100-m] MD from entering the reservoir, allowing for smooth steering/optimallanding, which would minimize mud loss. Before the bit reached the reservoir, OWC imaging–with an estimated ±6 ft [±2 m] of uncertainty–confirmed the presence of an oil column thickness greater than 33 ft [10 m], which confirmed the well's production potential.

Due to the successful landing, Shell continued using the GeoSphere system while drilling the reservoir section of this well and plans to use this system for landing future wells in the Draugen Field.