New multiscale measurement approach for geosteering in low resistivity and low contrast reservoirs: Cygnus field

December 2016, with 60% of the reserves being found in the Leman Formation. The Leman was initially developed in the best reservoir quality fault blocks via horizontal wells drilled with Periscope HD and borehole images. As the development progressed, poorer reservoir quality intervals were targeted. The 2012 FDP envisaged completion via fracture stimulation with associated risks and costs.

To address challenges in the latest Cygnus reservoir section, the worldwide first combination of measurements from the Geosphere HD and Periscope HD was utilised; combining two scales of depth of investigation and resolution. The results allowed for accurate placing within the thinly bedded and low contrast reservoir intervals, while being able to understand the well’s true stratigraphic position and the character of the Carboniferous subcrop in real time. The multiscale measurements helped Neptune to optimize the well path position and delivered greater confidence in decision-making whilst drilling.

Once the well was completed, it tested at higher rates than would have been expected and avoided a fracture stimulation. This tool combination has opened new development targets within other low reservoir quality areas on Cygnus.