Industry Article: Mapping-While-Drilling Technology Doubles Net Pay in Complex North Sea Reservoir

Thin injectite sand reservoirs in the North Sea have highly erratic boundaries with adjacent formations.

Mapping While Drilling
Publication: World Oil
Publication Date: 01/01/2015

Injectite sand reservoirs frequently have erratic boundaries with adjacent formations and their thicknesses often fall below conventional seismic data resolution. As a result, determining the stratigraphic location of reservoir boundaries and fluid contacts is almost always subject to uncertainty. Under such conditions, traditional methods of optimizing well placement suffer from critical limitations.

DONG used the GeoSphere reservoir mapping-while-drilling service to improve the accuracy of landing and steering of two horizontal wells in a thin sandstone injectite ranging in thickness from 2 to 15 m. The company had encountered significant challenges targeting the same type of remobilized sand reservoir in a nearby field using traditional image-based geosteering techniques.

The new service helped to improve the previous net pay ratio from less than 50% to an average 97%—essentially doubling reservoir exposure and production in each well. There were no sidetracks or delays, and both wells were completed within budget. Detailed information obtained while drilling helped refine the existing reservoir model, reduce uncertainties, and improve long-term field management.

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