Shedding the First Light on the Shilaif Source Rock in the Syncline, Onshore Abu Dhabi, UAE

Abstract

AbstractObjectivesConventional oil from the prolific carbonate reservoirs of Abu Dhabi has been produced over half a century from different anticlinal structures. Now, the time is right to go back to where it all started- the source rock in the depths of the syncline. The first well in the syncline provided an opportunity to characterize the reservoir quality of Cretaceous Shilaif Formation and understand the potential of the unconventional source rock oil play in Abu Dhabi.MethodsThe carbonate source rocks of Abu Dhabi are very different from the unconventional source rocks in the rest of the world and require a unique approach. An integrated workflow combining log, core and surface measurements has been carried out to characterize the Shilaif formation in the syncline in the south-western part of Abu Dhabi. Every measurement has a distinctive value and helps reduce uncertainties about Reservoir Quality. A critical examination of different available technologies was carried out to examine and optimize the characterization program to understand and reduce all uncertainties about reservoir quality.ResultsThe Shilaif source rock in this syncline to the south west of Abu Dhabi is a carbonate-rich organic mudstone, which distinguishes itself by lack of clay and vertical heterogeneity. It is a hybrid source rock with simultaneous presence of both organic and inorganic pores. The extensive core analysis program provided insights about porosity, permeability and saturation, which were used to validate the log interpretation. Higher thermal maturity and stronger compaction lead to different reservoir qualities than the ones previously recognized on the nearby shallower anticlinal structures. The reservoir quality of Shilaif in the syncline (levels of oil saturation, producible pore-sizes and permeability) exceed the pay criteria known to be required to produce economic volumes of oil in other basins around the world. Geomechanical characterization shows that the rock is extremely compact and requires careful planning with respect to proper completions and appropriate fracturing strategy for this play to be successfulNovel InformationThis is the first well in the syncline, targeting the mature source rock of Shilaif, based on previously existing literature. This paper explains the interpretation methodology workflow, that integrates all the measurements and discuss for the first time about viability of Shilaif as an economic source rock oil play in UAE, focusing on the syncline.