Optimize well positioning with extended depth of investigation
In considering the complexity of the reservoir structure, DONG E&P
decided to use the GeoSphere reservoir mapping-while-drilling service to steer
two planned horizontal production wells. The extended depth of investigation of
the service provides a map of the reservoir 100 ft [30 m] from the wellbore.
Deep directional electromagnetic measurements from this service are within the
same range as surface seismic measurements, and the two data sources can be
overlayed in real time while drilling to provide important look-ahead
information for optimized landing. This is especially significant given the
complex geometry of the Kolga Member reservoir.
Steer wells 96% in target zone while acquiring structural data
The combination of electromagentic measurements from the GeoSphere
service and surface seismic made it possible to steer ahead of reservoir
structure shifts. With better informed steering, the wells were placed within
the thin reservoir away from unstable shale and drilled completely to TD. The
two horizontal wells were steered optimally in the reservoir—96% in
zone—with no sidetracks. Both wells were tested at up to 8,000 bbl/d with
minimal drawdown.
The first well was drilled in a single run, achieving a horizontal
section of 2,674-ft [815-m] MD with a net-to-gross ratio of 0.98. Actual
reservoir exposure exceeded planned exposure by 213 ft [65 m], and the
tortuosity of the well was kept within requirements. The second well was
drilled in one run, achieving 853-ft [260-m] MD with a 0.96 net-to-gross
ratio.
Understanding of the reservoir and its heterogeneity was also greatly
improved. The information from the GeoSphere service was critical in refining
the reservoir model and, ultimately, for the long-term management of the
field.
Because of the successful well positioning and the valuable reservoir
mapping data acquired during drilling, DONG E&P plans to run the GeoSphere
service for future campaigns.