Search

Highlights • Petroleomics of crude oils recovered from the Mero Field, Santos Basin, Brazil. • The samples were generated under a thermal condition related to the peak of the oil window (0.7–0.9%Ro). • The samples were generated by a source-rock deposited in a lacustrine environment. • ESI FT-ICR MS is a trustworthy way to achieve a geochemical assessment. Abstract Three crude oils recovered from three different wells of the Mero Field in the pre-salt of the Santos Basin were selected for detailed geochemical analysis. The samples were analyzed using a 7.2 T LTQ FT-ICR MS instrument by negative electrospray ionization (–ESI), focusing on the polar compounds, i.e., nitrogen-, sulfur-, and oxygen-containing compounds (NSO). Additionally, a combination of traditional geochemical methods including GC-FID, GC-MS, and carbon isotopic composition (whole oil and n -alkanes) were used to assess the samples. Through this work, it was demonstrated that –ESI FT-ICR MS is a reliable method for assessing crude oil composition and providing information about the origin and thermal maturity of the samples. Results showed that the dominant heteroatom classes are N 1 , O 2 , N 1 O 1 , and O 1. Due to the similarity of double bound equivalent (DBE), which means number of unsaturation present in an organic molecule, and carbon number distributions for the N 1 class species it is possible to suggest that Mero's filling history had an oil charge representing the peak of the oil window (0.7–0.9 %Ro) and that the oils were generated by a source rock deposited in a lacustrine environment. [ABSTRACT FROM AUTHOR]

Highlights • Petroleomic was applied to 69 off-shore Brazilian crude oils samples. • Kerogen type plays an important control on NSO compounds. • Clear separation based on polar species found in marine and lacustrine oils. • Negative ESI FTICR-MS can be used to perform geochemical assessment in crude oils. Abstract Lacustrine and marine crude oils from different off-shore Brazilian basins were analyzed using a 7.2 Tesla LTQ FTICR-MS instrument. The samples were analyzed via electrospray ionization in the negative ion mode focusing on the polar compounds, i.e., nitrogen-, sulfur-, and oxygen-containing (NSO) compounds. We also employed a combination of other geochemical methods, such as GC-FID and GC-MS analyses, to characterize and assess the depositional environments of the different oil families. The results indicate that lacustrine oils tend to be enriched in Nx compounds, while marine oils show preference for Ox compounds. The dominant heteroatomic classes in crude oils are N1, followed by O1, O2, and N1O1 with remarkable differences in their distributions between marine and lacustrine, strongly suggesting the control by the kerogen type of the heteroatomic compounds found in these crude oils. Considerable differences in the DBE distribution of the main classes analyzed between the crude oils allowed an efficient geochemical characterization regarding their origin. The use of negative ESI FTICR-MS as a geochemistry tool can provide additional information beyond that obtained with currently employed geochemical methods, resulting in the full comprehension of crude oil composition. [ABSTRACT FROM AUTHOR]

The thermal maturity level impact on polar compounds was analyzed for a suite of hydrous pyrolysis (HP) products using a 7.2 Tesla LTQ FTICR-MS instrument. The sample suite was analyzed via electrospray ionization in the negative ion mode focusing on the polar compounds, i.e., nitrogen-, sulfur-, and oxygen-containing (NSO) compounds. The HP experiments were performed under isothermal conditions for 2 h at eleven different temperatures (300, 310, 320, 325, 330, 340, 345, 350, 355, 360 and 365 °C) to simulate the full range of thermal levels starting at early bitumen generation to maximum oil generation. The maturity suite samples consist of one immature bitumen (original sample), eleven expelled oil samples and eight residual bitumen samples. In general, O x compounds are destroyed by decarboxylation and dehydration with increasing maturity; sulfur compounds decrease; the aromaticity and degree of condensation increase; and steranoic and hopanoic acids decrease. Additionally, we investigated fluid retention properties comparing the carbon number distribution between the expelled oil and residual bitumen samples from each experiment. The maturity related changes of the acidic O 2 compounds in the expelled oil samples led us to create several regressions that we propose as new maturity parameters covering the full range of oil generation. [ABSTRACT FROM AUTHOR]