Abstract:
A 3D outcrop depositional facies investigation of carbonate reservoir analog requires a comprehensive integration between outcrop with "behind-the-outcrop" geophysical data. This study proposes a comprehensive methodology to assess, process, and synthesize photogrammetry, sedimentology, ground penetrating radar (GPR), and seismic datasets based on the outcrop depositional facies framework. The methodology was tested and applied to map the 3D morphology of the stromatoporoid/coral buildups in the Late-Jurassic Hanifa reservoir analog at Wadi Birk, Saudi Arabia. Datasets acquired include 1.2 km2 drone imageries; measured sections; 8 km-long networks of 2D GPR, three grids of 3D GPR (60 m x 50 m; 50 m x 20 m; 55 m x 40 m); 640 m-long 2D seismic profile; and a 50-m long core. We constructed a digital outcrop model (DOM) from drone imageries and calibrated it with measured sections. We measured dielectric permittivity, acoustic velocity, and bulk density to assess the geophysical properties of the target facies. We utilized DOM-based GPR and seismic models to assess the geophysical responses and formulate processing flows that accentuate anomalies from the stromatoporoid/coral facies. We utilized the proposed methodology to measure the 3D morphology of the stromatoporoid/coral buildups quantitatively. The buildups are 3D pseudo-ellipsoid with an average long and short axis length of ~36 m and ~11 m, respectively. The average thickness of the buildups is ~2.6 m with ~N335E orientation. We utilized these statistical measurements to construct an outcrop-based porosity model of the Hanifa reservoir analog that honors the observed 3D morphology of the stromatoporoid/coral facies.