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

Abstract

SUMMARYModelling 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.

Dolomite recrystallization revealed by Δ47/U-Pb thermochronometry in the Upper Jurassic Arab Formation, United Arab Emirates

“…A burial curve for the Arab Fm. from both crest and flank of the studied anticline field is available from Al Darmaki et al (2014) who applied back-stripping analysis. Accordingly, the investigated reservoir unit from the anticline crest reached peak burial conditions (~3 km) in the Miocene.…”

Supplemental Material: Dolomite recrystallization revealed by Δ₄₇/U-Pb thermochronometry in the Upper Jurassic Arab Formation, United Arab Emirates

“…A burial curve for the Arab Fm. from both crest and flank of the studied anticline field is available from Al Darmaki et al (2014) who applied back-stripping analysis. Accordingly, the investigated reservoir unit from the anticline crest reached peak burial conditions (~3 km) in the Miocene.…”

Limited thermochemical sulfate reduction in hot, anhydritic, sour gas carbonate reservoirs: The Upper Jurassic Arab Formation, United Arab Emirates

“…These temperatures are comparable to bottom hole temperatures in the crest and flanks, respectively. The homogenization temperatures (T h ) coupled with the modeled burial-tectonic history (Al Darmaki et al, 2014;Fig. 8) suggest that TSR commenced at around 2.7 km depth around 35-50 Ma ago (Early to Late Eocene).…”