3D Geomechanics modeling to assess hydraulic fracture containment and unlock the potential of reservoirs bounded by thin caprocks through horizontal producers - a case study in UAE

ABSTRACT: A 3D geomechanics model (3D-MEM) has been constructed to better understand the risks of cap rock breaching during hydraulic fracturing in a carbonate reservoir surrounded by thin cap rocks. The model was built using a comprehensive data set of rock mechanical properties, reservoir pressure and stress tests. The equilibrated stresses from the 3D-MEM was used to perform a 3D Completion Quality analysis (3D-CQ), based on five drivers for hydraulic fracturing assessment: fracture gradient, stress contrast, qualitative fracture height, stress regime and direction. All the attributes were analyzed to better understand the expected fracture performance. Of them the most important is the fracture height attribute as directly assesses about fracture contention within the cap rocks. The qualitative fracture height (FH) results were compared with those obtained from a fracture height Numerical simulation using a reference fracture treatment. This attribute will help to better assess the fracture containment at 3D level. The results were consistent with the numerical simulation, while becoming a practical way to assess fracture containment from 3D geomechanics attributes. The case study modeling results proved that the overlying and underlying cap rocks are strong enough to support a small fracture treatment in horizontal wells, and that the incorporation of elements like faults and laminations could play a significant role in derisking the entire operation.