Well Placement and Reservoir Characterization Challenges on Peregrino Mitigated by Development of Extra-Deep Azimuthal EM Technology

Antonsen, Frank (Statoil) | Barbosa, Jose Eustaquio Pampuri (Statoil) | Morani, Beatriz (Statoil) | Klein, Katharine (Statoil) | Kjølleberg, Marie (Statoil) | McCann, Andrew (Statoil) | Olsen, Per Atle (Statoil) | Constable, Monica Vik (Statoil) | Eidem, Morten (Statoil) | Gjengedal, Jakob Andreas (Statoil) | Antonov, Yuriy (Baker Hughes) | Hartmann, Andreas (Baker Hughes) | Larsen, David (Baker Hughes) | Skillings, Jon (Baker Hughes) | Tilsley-Baker, Richard (Baker Hughes)



Statoil faced significant well placement challenges while drilling the first development wells on the Peregrino field, offshore Brazil, resulting in lower sandstone contact and production than expected. Efficient drainage from the gravity flow sandstone on this heavy oil field requires a high level of sandstone contact. The need for a deeper azimuthal LWD-measurement was identified as necessary for Peregrino to increase sandstone content in the horizontals by improving the ability to steer within relatively thin sandstone bodies, or to identify and drill neighboring thicker sandstone bodies above or below the well trajectory.

Statoil started a technology collaboration project with Baker Hughes in 2011 to accelerate the development of an extra-deep azimuthal resistivity measurement to address the Peregrino well placement challenges. The first wells utilizing the new LWD technology were drilled in 2012, and the technology has been applied in more than 20 wells on Peregrino so far. This valuable experience is currently transferred to fields on the Norwegian Continental Shelf (NCS).

The extra-deep azimuthal resistivity (EDAR) tool enabled Statoil to avoid pilot holes for stratigraphic control and landing, and to enhance the proactive geosteering within the complex Peregrino reservoir sandstone, resulting in increased reservoir exposure and production. The extra-deep look-around measurements, sensitive to contrasts 20 m from the wellbore or more in favorable conditions, is bridging the gap between traditional wellbore measurements and seismic data; by integrating these data types, interpretation of the reservoir structure and geometry can be refined, resulting in better constrained reservoir models and an improved field development strategy.

This paper presents examples of extra-deep resistivity measurements from reservoir sections drilled on Peregrino to illustrate the technology development, well placement experiences and learnings pertaining to real-time interpretation and geomodel updates. The initial experiences from the Norwegian Continental Shelf will also be presented to explain how the technology works in various geological settings.

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