Natural Fractures Sensitivity to Hydraulic Fractures in Abu Dhabi, UAE

Abstract Fractures serve as important conduits for subsurface fluid flow and their presence can transform an otherwise unproductive rock formation into an economic hydrocarbon reservoir. Natural fractures have a vivid impact on reservoirs, especially the low perm, as they control the hydraulic flow as conductors (open fractures) or barriers (sealed fractures). Abu Dhabi carbonates are dissected by many fracture clusters, but most of them are sealed, therefore it is critical to investigate, which sets are predicted to reactivate. Hydraulic fracturing in horizontal drilling are the primary enabling technology to gain economical production from the low perm reservoirs. However, fracture parameters are poorly constrained by reservoir data, due to they are subseismic and hard to predict their behaviour through the life-cycle of the reservoir. Addressing the structural patterns and using the geomechanical data along well bores help to assess their roles in production enhancement and sensitivity to hydraulic fractures initiation and propagation. The spatial distribution of microfaults, hybrid fractures and pure opening mode fissures with wide variations in strike appears related to their location with respect to the deformation zones of the nearby fault segments in the reservoirs of Abu Dhabi. Usually not all fracture sets enhancing production and the best approach is to predict those sets that playing these roles. The ability of fractured bedrock to transmit fluids depends upon the physical characteristics of the fractures and opening-mode fractures that make up the fracture system, such as fracture aperture, fracture length, fracture density, fault displacement and gouge thickness. Many of the hydraulically significant fractures at the reservoir scale cannot directly detected, neither by borehole imaging tools nor by seismic imaging. Thus, reservoir characterization, in terms offracture architecture models, are derived from a combination of well data and the factors that control fracture development in carbonate reservoirs of Abu Dhabi. These factors include stratigraphy, rock properties, kinematics, especially orientations and mechanics of fracture growth and principally their relation to the present day in situ stresses. The results showing that, hydraulic fractures propagation is dependent on the natural fractures and bedding planes orientations and the well location relative to the fault segments deformation zones. Understanding and predicting the behavior of fractures involves the identification and location of hydraulically significant fractures. Such fractures are conduits for fluid flow, and are connected to other hydraulically conductive fractures to form conduit systems. Conductive fracture networks may include a large number of interconnected hydraulically active fractures, or may be limited to a very small proportion of the total fractures in the rock mass.