Abstract:

Sub-seismic meter-scale interwell depositional facies heterogeneity and microporosity are critical components behind properties and fluid flow heterogeneities of many Middle eastern giants and supergiants carbonate reservoirs. The Hanifa reservoir is one of the most petroliferous Arabian carbonate strata that hosts the notoriously heterogenous stromatoporoid/coral facies. Paradoxically, the 3D geometry, architecture, and subsurface implication of these facies are poorly understood or completely ignored in most studies. The lower part of the Arab-D reservoir is dominated by microporosity. However, studies that investigate the influence of microcrystals that host microporosity to petrophysical properties and upscale it to reservoir simulation grid-block scale are modicum. This dissertation aims to bridge this paucity by performing an advanced three-dimensional outcrop analog investigation and multiscale microporosity studies of these formations. We document the 3D morphology and spatial distribution of the stromatoporoid/coral facies part of the Hanifa reservoir outcrop analog in Wadi Birk, Saudi Arabia, using 3D drone-based digital outcrop model, cores, near-surface geophysical measurements, and deep-learning methodology. We construct a high-fidelity outcrop analog reservoir model from these observations and utilize it for dynamic simulation during waterflood. Further, based on the Upper Jubaila Formation outcrop analog in Wadi Laban, Saudi Arabia, we investigate the influence of microcrystals that host microporosity on petrophysical properties. We upscale the relationships and utilize seismic-derived acoustic-impedance data to arrive at reservoir grid block-scale microporosity distribution. Our results provide a novel and valuable insight into the growth morphology of the stromatoporoid/coral buildups and their relationship with subsurface fluid flow previously unknown for the Hanifa reservoir. The results demonstrate that sweep efficiency is greatly influenced by the interaction between the buildup clusters with the background strata. Our results also provide a practical method to integrate key sub-grid scale micro and macro heterogeneities into reservoir grid block-scale property models.