LIDAR OUTCROP ANALOGUES OF A NATURALLY FRACTURED CARBONATE RESERVOIR: INFLUENCES OF STRATIGRAPHIC HETEROGENEITY AND SURFACES - A SEQUENCE STRATIGRAPHIC FRAMEWORK: EOCENE, THEBES FORMATION, WEST CENTRAL SINAI, EGYPT

Fractures are important elements of many hydrocarbon reservoirs influencing fluid flow and permeability. Outcrop analogue studies can assist in characterising naturally fractured reservoirs to reveal the fundamental geological controls on fracture networks and aid subsurface fracture network prediction and flow modelling. Much work has been carried out previously on the influences of structural setting on fracture networks. This study focuses on the equally important controls stratigraphic heterogeneity, surfaces and boundaries have on mechanical stratigraphy. Several potential stratigraphic controls on fracturing, including bed thickness, lithological contacts, discontinuities, hard grounds, chert, and sedimentary and diagenetic heterogeneity can be predicted in a sequence stratigraphic framework. Ground-based LiDAR scan data has been used to construct two 3D Digital Outcrop Models (DOM) of a thinly bedded (Lowstand Systems Tract) and a thickly bedded (Transgressive Systems Tract) naturally fractured carbonate analogue of the Eocene Thebes Formation exposed in the western central Sinai, Gulf of Suez, Egypt. The shallow water prerift Thebes Formation carbonates form a naturally fractured hydrocarbon reservoir (Rudeis-Sidri oil field). Sedimentological and diagenetic data from sedimentary logs and petrography have been added to the DOMs. Quality control is provided by conventional outcrop scan lines. LiDAR has several advantages over tradition field methods. By virtually accessing the whole outcrop LiDAR eliminates selective bias and can be used to generate large quantitative statistically significant data sets including stratal thicknesses, bedding orientations, fracture lengths, spacings and orientations. Quantitative structural and stratigraphic measurements have been abstracted from the DOMs using Virtual Reality Geological Studio (VRGS) software with the objectives of: (1) characterising different fracture sets; (2) statistically identifying and characterising mechanical interfaces at which fractures initiate or are arrested; (3) characterising fracture lengths and spacings within the identified mechanical units. This data is translated into geological rules for predicting fracture patterns in the subsurface within a sequence stratigraphic framework.