The Pyrenees Field comprises a series of biodegraded 19° API oil accumulations reservoired in Early Cretaceous sandstones of the Pyrenees Member in the Exmouth Sub-Basin, offshore WA The reservoir comprises excellent quality, poorly consolidated shallow marine to deltaic sands. Variable thickness oil columns (some with associated gas caps), strong bottom water drive, and relatively viscous oil has necessitated the drilling of long (up to 2,000 m) horizontal wells to maximise reservoir exposure while geosteering well to within a few meters of the roof of the reservoir to maximise standoff from the OWCs. The field is covered by excellent quality 3D seismic data; however, pre-drill mapping for well path planning is complicated by the unconformable nature of the top reservoir boundary formed by the sub-cropping Pyrenees Member. Faulting within and localised velocity variations above the reservoir are also a challenge to pre-drill well planning. Cutting-edge geosteering tools have been used to achieve the desired well paths. The tools use azimuthal deep induction resistivity measurements to model and predict reservoir and fluid boundaries, taking advantage of the large resistivity contrasts between the overlying sealing mudstones of the Muderong Formation and the oil (and occasionally gas) bearing Pyrenees reservoir sands. This extended abstract discusses the application of the tools both in pre-drill well path planning and the real-time geosteering operation. Operations are managed between the rig and a sub-surface team located in a dedicated geosteering room onshore. Here real-time data is compared with planned well paths in 3D seismic and geocellular reservoir models and well path adjustments made to optimise final well placement.
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