Geothermometry and geochemistry of aqueous and oil-bearing fluid inclusions from Fateh Field, Dubai

Abstract

The production of oil from Fateh Field, Dubai, is principally from the Cretaceous Mishrif Formation. Porosity in the reservoir facies is partly occluded by late, coarse-grained calcite cement. This cement contains both aqueous and oil-bearing fluid inclusions. Fluid inclusion geothermometry was used to determine the temperature of that cement precipitation and calculate its timing relative to basin burial history. These data were related to source rock maturation, and from that, the timing of oil migration was inferred to be Oligocene to mid-Miocene, which is geologically contemporaneous with early petroleum generation ( R 0 = 0.5−0.6%) in the Khatiyah source rock. The fluid inclusions were analyzed by a thermal decrepitation-gas chromatography technique. Benzene and low molecular weight paraffins were present, and a series of normal alkenes was tentatively identified in the aqueous inclusions. Fresh oil inclusions consisted of C 1- n-C 25 compounds whose light hydrocarbon composition was consistent with derivation from an early mature source rock. Altered petroleum residues detected in many Mishrif samples are contained either in inclusions or along crystal cleavages. These materials are the subject of an ongoing geochemical study of Fateh Field.