Operator Maintains 5-ft Drilling Target Window for 6,890-ft Horizontal Well Offshore Australia | SLB

Operator Maintains 5-ft Drilling Target Window for 6,890-ft Horizontal Well Offshore Australia

Published: 06/26/2014

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Drill within narrow target zone in challenging horizontal well

An operator in Australia wanted to maximize exposure to good quality sands in thinner oil columns and drill longer horizontal trajectories, up to 6,890 ft [2,100 m] offshore Australia. It set a target window of drilling 5–10-ft [1.5–3-m] TVD below the reservoir top to minimize attic oil production and avoid OWC. The target would have to be maintained within the target window for the length of the 6,890-ft [2,100-m] well section. However, the lower net and interbedded nature of the field presented reservoir steering challenges.

Use real-time mapping to find good quality reservoir sands, drill on target

The operator selected the GeoSphere reservoir mapping-while-drilling service, which extends the depth of investigation to more than 100 ft [30m] and provides increased detail of subsurface reservoir layers and fluid contacts. Using deep directional resistivity measurements, the service maps reservoirs, enabling operators to adjust drilling plans and drill on target in complex downhole environments.

Optimized drilling plan, maintained trajectory in sweet spot

With the real-time reservoir mapping data from the GeoSphere service, the operator adjusted its drilling plans for optimal exposure and stayed within its revised target zone for the length of the well. Reservoir mapping revealed good quality reservoir sands 10-ft [3-m] TVD lower than expected. The GeoSphere service also clearly mapped the top of the reservoir with delineated layers, showing a dip of 3–5º. This data aided in accurate drainhole placement in the target zone. The operator maintained its drilling window of 5-10-ft [1.5–3-m] TVD below the reservoir top, avoided OWC, and minimized attic oil. As a result, the operator selected the GeoSphere service for use in four additional wells.

Graph: Operator Maintains 5-ft Drilling Target Window for 6,890-ft Horizontal Well Offshore Australia
Top: The GeoSphere service was used to evaluate the oil column and delineate layering within the reservoir, which had a structural dip of 3°–5°. Bottom: This enlarged view shows the drilling precision made possible by the GeoSphere service.
Australia, Oceania, Offshore

Challenge: Minimize attic oil and avoid oil/water contact (OWC) in a horizontal well up to 6,890 ft [2,100 m] long by steering and maintaining wellbore 5–10-ft [1.5–3-m] below top of reservoir

Solution: Use the GeoSphere reservoir mapping-while-drilling service to drill a 6,890-ft [2,100-m] horizontal well in narrow target window


  • Optimized the steering window on the basis of mapping-while-drilling information used to evaluate the oil column
  • Maximized exposure to good-quality reservoir sands, avoided the OWC, and minimized attic oil by drilling in the target window
  • Determined that the layers dipped 3°–5°
Products Used