3-D DIGITAL OUTCROP ANALOGUES OF NATURALLY FRACTURED CARBONATE RESERVOIRS - INTEGRATING MECHANICAL AND SEQUENCE STRATIGRAPHY: EXAMPLES FROM THE EOCENE THEBES FORMATION OF EGYPT

Fractures are important elements of many hydrocarbon reservoirs influencing fluid flow and permeability but are difficult to characterise in the subsurface. Fracture networks are typically below the resolution of seismic reflection surveys and their study is often reliant on widely spaced borehole data. Outcrop analogue studies can assist in characterising naturally fractured reservoirs to reveal the fundamental geological controls on fracture networks, aid subsurface fracture network prediction, and provide quantitative data for use in flow models. In this study ground-based LiDAR scan data has been use to construct quantitative 3-D photorealistic Digital Outcrop Models (DOM) of analogues of naturally fractured carbonate reservoirs excellently exposed in the western central Sinai desert, Gulf of Suez, Egypt. The shallow water prerift Thebes Formation carbonates form naturally fractured hydrocarbon reservoirs currently in production in the subsurface (Rudeis-Sidri oil field). Quantitative measurements have been abstracted from the DOM automatically using Virtual Reality Geological Studio (VRGS) software. This data-set includes: fracture spacing (density), fracture lengths, fracture aperture, fracture connectivity, fracture orientations, bedding thicknesses and orientations, and the identification of mechanical units and interfaces. Quality control is provided by traditional outcrop measurements. Additional data from petrographic and diagenetic studies have been added to the model. The statistically significant VRGS derived data-set is translated into geological rules for predicting fracture patterns in the subsurface. Several potential controls on fracturing, including bed thickness, lithological alternations, and diagenetic heterogeneity can be predicted within a sequence stratigraphic framework. A key aims of this study is to integrate mechanical stratigraphy and sequence stratigraphy.