Correlation of fluid inclusions and reservoired oils to infer trap fill history in the South Viking Graben, North Sea

Abstract

Organic geochemical correlations between fluid inclusions and associated oils and oil-shows in Mesozoic reservoirs in the Sleipner area demonstrate generation from the same source rock organic facies (type II) for inclusions in wells 15/9-1 and 15/9-19. For well 15/9-9 the oil show is from a mixed type II/III source rock, whereas the fluid inclusion is from a type II source. All fluid inclusions are less thermally mature than the associated free oils and are thought to represent the earliest hydrocarbon yield from the source rocks. GC/MS/MS analyses of the fluid inclusions proved essential for resolving biomarker compounds and correlating them to reservoired fluids. Among the biomarkers, bisnorhopane contents in the fluid inclusions are consistently lower than in the associated reservoired oil. The expected dilution effect of bisnorhopane as progressively more hydrocarbons are generated from kerogen maturation is not observed. The difference in bisnorhopane amounts in fluid inclusions and oils is primarily due to varying relative hydrocarbon yields, through time, from different source rocks.

Fluid inclusion evidence for an early, marine-sourced oil charge prior to gas-condensate migration, Bayu-1, Timor Sea, Australia

“…Isaksen, Pottorf, & Kenssen, 1998;Karlsen, Nedkvitne, Larter, & Bjørlykke, 1993;Lisk, George, Summons, Quezada, & O'Brien, 1996), it is likely that these oil inclusions contain oil from the earliest oil charge into the Bayu-Undan reservoir. Whilst a small number of inclusions appeared to have a low liquidvapour ratio and could represent inclusions trapped as gas that subsequently condensed out a liquid rim during retrieval of the samples to the surface (a condensate inclusion), this could not be demonstrated unequivocally.…”

2. Mechanism and Upfault Seepage and Seismic Expression of Hydrocarbon Discharge Sites from the Timor Sea

“…Conventional oil and gas shows can be combined with unconventional oil and gas shows provided by oil-bearing fluid inclusions to investigate hydrocarbon-fluid contacts and to provide a more comprehensive evaluation of the oil-charge history and oil-migration risks in petroleum reservoirs (e.g., Karlsen et al, 1993;Lisk and Eadington, 1994;Isaksen et al, 1998;Lisk et al, 1998Lisk et al, , 2001Brincat et al, 2001;Gartrell and Lisk, 2005;Brincat et al, 2006).…”

Application of fluid inclusion studies to understanding oil charge, Pre-Salt succession, offshore Angola

“…Organic geochemistry can be made more specific by coupling gas chromatography to mass spectrometry, which allows determination of maturation parameters and source typing, and correlation with source rocks and other oils (e.g. George et al 1997;Isaksen et al 1998). Oil composition can also be constrained by non-destructive and destructive techniques directed at individual inclusions, including Raman spectroscopy (Wopenka et al 1990), infrared spectroscopy (Barres et al 1987), confocal scanning microscopy (Aplin et al 1999), micropyrolysis (Greenwood et al 1998), and time-of-flight secondary ion mass spectrometry (Mazzini et al 2002).…”