oa Identification, Upscaling and Modeling Strategy for Multi-Scale Fracture Networks in Variable Lithology Reservoirs

Modelling of multi-scale fracture and fault networks is highly uncertain, relying typically on a range of parameters (size, shape, flow properties, connectivity, spacing, orientation) with individually large or sometimes unknown ranges which are very difficult to quantify. Analog data can be used, but resulting models are often unsuitable for well placement or detailed production monitoring in fields under development. Borehole image data are critical in the static (geological) description of the fracture network, but in the absence of dynamic information (e.g. mud losses while drilling, PLT, production, long-term well test) the relative contribution of fractures and fracture networks is speculative. This study highlights the challenges of building a hierarchical description of fractures and connected conduits in a sour gas reservoir which has not started production. In addition, constraining dynamic behaviour is hampered by extreme operational limitations (only short duration well tests and production logging is not feasible). This case study describes a workflow for characterising fault / fracture networks in the pronounced mechanically layered Arab Formation (Late Jurassic) reservoirs of onshore UAE.