Resolving Meter-Scale Interwell Depositional Heterogeneities for Improved 3D Reservoir Modelling – High Resolution 3D Photogrammetry and Geophysical Outcrop Surveys of Late-Jurassic Reservoir Rocks, Saudi Arabia

Interwell meter-scale depositional heterogeneity is a key geologic factor behind un-even fluid advance in carbonate reservoirs undergoing waterflooding and enhanced oil recovery developments. Subsurface data (seismic and well data) are limited in both resolution and data density to resolve this level of heterogeneity. Outcrop analogues are commonly utilized to fill this data gap on interwell heterogeneity. However, most outcrop analogue studies are limited to vertical sections and two-dimensional interpolated profiles. This study builds from outcrops high-fidelity 3D depositional models using 3D drone photogrammetry, cores and 3D geophysical data. We applied our methodology to the top 40 m of the Late-Jurassic Hanifa Formation outcrop in Wadi Birk, Saudi Arabia. Datasets include a multi-resolution 16 km2 drone photogrammetry survey over criss-crossing wadi systems, measured vertical sections from 10 different locations including spectral gamma-ray, 160 hand samples and thin sections, three 50 m-long cores taken from behind the outcrops, a 19 km-long network of 2D and 3D Ground Penetrating Radar, and 1.9 km of 2D seismic. The overall cleaning upward succession contains shallow marine wackestones-packstones at the bottom, followed by stromatoporoid-coral complex (with m-scale lateral and vertical heterogeneity) that is capped by oncolithic and cross-bedded peloidal grainstones at the top. The stromatoporoid-coral buildups display biostromal-biohermal morphology with inter-buildup space filled by wackestones-floatstones-grainstones. The smaller stromatoporoid-coral complexes (less than 10 m) are more circular, while the larger are pseudo-ellipsoid (30-50 m long, 5-10 m wide), indicating preferential alignment with local-regional currents.