Downdip-Oil Potential for an Onshore Abu Dhabi Petroleum System

Abstract

Summary A combination of fluid-inclusion and geochemical analyses was conducted on rocks and reservoir fluids to develop an improved understanding of downdip-oil potential in a mature exploration play, onshore Abu Dhabi, UAE. Exploration for oil in the region is complicated by low-permeability carbonate reservoirs, poor seismic imaging, and complex hydrocarbon-maturation and -migration histories. In addition, a broad range of fluid properties, including gas, condensate, and high-°API oil, makes evaluation of the reservoir fluid phase difficult. In this challenging environment, geochemical and fluid-inclusion techniques are effective tools for identifying downdip oil potential from gas-cap fluids and reservoir-rock samples. Fluid-inclusion data are used to develop a hydrocarbon-emplacement history, which constrains the distribution of fluids throughout the exploration area. In some areas, undersaturated gas inclusions trapped at present-day temperatures suggest a low chance for downdip oil. Conversely, other structures contain oil inclusions that have been displaced recently by saturated gas, suggesting good potential for downdip oil. Geochemical analyses of recovered fluids were used independently to predict the likelihood of down-dip oil. These combined techniques were placed in a geologic framework to regionally risk the potential for downdip oil throughout the exploration area. This framework enables improved resource evaluation and prioritization of exploration efforts in areas of the play where a high probability of downdip oil exists.