Compound-specific isotope analysis as a tool for characterizing mixed oils: an example from the West of Shetlands area

Rooney, Melodye A.; Vuletich, A.K.; Griffith, Christine

doi:10.1016/s0146-6380(98)00136-3

Cited by 77 publications

(46 citation statements)

References 15 publications

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“…However, this observation can be explained if the oil is considered to contain a mixture of lightly and heavily biodegraded oils (Nascimento et al, 1999;Pan et al, 2003;Philp, 1983;Rooney et al, 1998;Volkman et al, 1983). Thus, this assemblage of biomarkers is consistent with a reservoir mechanism involving at least two charges, with an earlier charge experiencing heavy biodegradation while a subsequent charge is essentially unaltered by microbes.…”

Section: Figure 5 and Table 2 Near Herementioning

confidence: 70%

Combining biomarker and bulk compositional gradient analysis to assess reservoir connectivity

Pomerantz

Ventura

McKenna

et al. 2010

Organic Geochemistry

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Abstract:Hydraulic connectivity of petroleum reservoirs represents one of the biggest uncertainties for both oil production and petroleum system studies. Here, a geochemical analysis involving bulk and detailed measures of crude oil composition is shown to constrain connectivity more tightly than is possible with conventional methods. Three crude oils collected from different depths in a single well exhibit large gradients in viscosity, density, and asphaltene content. Crude oil samples are collected with a wireline sampling tool providing samples from well-defined locations and relatively free of contamination by drilling fluids; the known provenance of these samples minimizes uncertainties in the subsequent analysis. The detailed chemical composition of almost the entire crude oil is determined by use of comprehensive two-dimensional gas chromatography (GC×GC) to interrogate the nonpolar fraction and negative ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) to interrogate the polar fraction. The simultaneous presence of 25-norhopanes and mildly altered normal and isoprenoid alkanes is detected, suggesting that the reservoir has experienced multiple charges and contains a mixture of oils biodegraded to different extents. The gradient in asphaltene concentration is explained by an equilibrium model considering only gravitational segregation of asphaltene nanoaggregates; this grading can be responsible for the observed variation in viscosity. Combining these analyses yields a consistent picture of a connected reservoir in which the observed viscosity variation originates from gravitational segregation of asphaltene nanoaggregates in a crude oil with high asphaltene concentration resulting from multiple charges, including one charge that suffered severe biodegradation. Observation of these gradients having appropriate magnitudes suggests good reservoir connectivity with greater confidence than is possible with traditional techniques alone.3

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Section: Figure 5 and Table 2 Near Herementioning

confidence: 70%

Combining biomarker and bulk compositional gradient analysis to assess reservoir connectivity

Pomerantz

Ventura

McKenna

et al. 2010

Organic Geochemistry

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“…Expelled gas and oil tend to be 13 C-depleted in comparison with the residual kerogen by c. 2‰. Even though the knowledge of these effects and of the extent of their control on bulk δ 13 C values of petroleum has been used in petroleum exploration since the 1970s (Stahl 1977;Schoell 1984;Sofer 1991), the use of CSIA (Chung et al 1994;Rooney et al 1998;Whiticar & Snowdon 1999;Odden et al 2002) would benefit from further knowledge of the effects of thermal maturation on individual hydrocarbons.…”

Section: Om Maturation and Petroleum Generationmentioning

confidence: 99%

Carbon and hydrogen isotopic compositions of n -alkanes as a tool in petroleum exploration

Pedentchouk

Turich

2017

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Compound-specific isotope analysis (CSIA) of individual organic compounds is a powerful but underutilized tool in petroleum exploration. When integrated with other organic geochemical methodologies it can provide evidence of fluid histories including source, maturity, charge history and reservoir processes that can support field development planning and exploration efforts. The purpose of this chapter is to provide a review of the methodologies used for generating carbon and hydrogen isotope data for mid-and high-molecular-weight n-alkanes.We discuss the factors that control stable carbon and hydrogen isotope compositions of n-alkanes and related compounds in sedimentary and petroleum systems and review current and future applications of this methodology for petroleum exploration. We discuss basin-specific case studies that demonstrate the usefulness of CSIA either when addressing particular aspects of petroleum exploration (e.g. charge evaluation, source rock-oil correlation, and investigation of maturity and in-reservoir processes) or when this technique is used to corroborate interpretations from integrated petroleum systems analysis, providing unique insights which may not be revealed when using other methods. CSIA of n-alkanes and related n-alkyl structures can provide independent data to strengthen petroleum systems concepts from generation and expulsion of fluids from source rock, to charge history, connectivity, and in-reservoir processes.Gold Open Access: This article is published under the terms of the CC-BY 3.0 license.Petroleum geoscientists use organic geochemistry as an essential tool in oil and gas exploration and field development planning. Relatively low-cost, high-throughput bulk data are commonly used to screen for source rock quality (e.g. per cent total organic carbon (%TOC), hydrogen and oxygen indices) and thermal maturity (Tmax, vitrinite reflectance equivalent). More in-depth geochemical analytical techniques are used in the context of full fluid and reservoir properties to correlate source rocks and reservoir oils, to determine fluid generation and migration history, including presentday reservoir connectivity, and to understand in-reservoir processes, such as biodegradation of in-reservoir oils. These tools are especially powerful when coupled with other measurements made during the exploration and development process, such as compositional analysis during drilling, downhole fluid analysis and other wireline measurements, and pressure, volume, temperature (PVT) and chemical analyses, integrated in the context of geological static and reservoir dynamic models.Molecular biomarkers have been employed in petroleum exploration for several decades (Peters et al. 2005). The usefulness of bulk stable isotope measurements of gases and oils was well demonstrated in the petroleum industry through the decades of the 1970s and 1980s (Stahl 1977;Schoell 1984;Sofer 1984). However, the use of compound-specific isotopic composition of light hydrocarbons, alkanes and biomarkers is less common....

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“…The stable carbon isotopic ratios of individual hydrocarbon in the range fraction (C 6 -C 7 ) are used to characterize and correlate oils and gases (Rooney et al, 1995;Rooney et al, 1998;Whiticar and Snowdon, 1999). LMWH of gas from the O1m5 reservoir is 13 C enriched and the δ 13 C values range from −25.4% to -16.3%.…”

Section: The Stable Carbon Isotopic Ratio Of C 6 -C 7 Individual Hydrmentioning

confidence: 99%

Characterization of Low Molecular Weight Hydrocarbons in Jingbian Gas Field and its Application to Gas Sources Identification

Zhang

2011

Energy Exploration & Exploitation

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Chemical and isotopic compositions of C 6 -C 7 low molecular weight hydrocarbons (LMWHs) were used to determine the origin of gas in the Ordovician weathered crust (O1m5) reservoir of Jingbian gas field in Ordos Basin, China. GC quantification of LMWHs for 55 gas samples [20 of them from the Xiashihezi Formation (P1x) and Shanxi Formation (P1s) reservoirs, and the rest from the O1m5 reservoir] were conducted. The compound specific stable carbon isotopes of LMWHs for 24 gas samples (five gas samples from the P1s reservoir) were analyzed with GC-C-IRMS. The results show that cycloalkanes are abundant components and their concentrations range from 23.8-52.5% with an average of 41.1% among LMWHs. Methylcyclohexane (MCH) is the most abundant one among normal heptane (n-C 7 ), MCH and dimethylcyclopentane (DMCP), ranging from 50.1-81.4% with an average value of 71.6%. A 13 C enrichment for nine compounds of C 6 -C 7 fraction was observed, and the δ 13 C values range from −25.4-16.3%. Based on the correlation of the Mango parameters (K1 and K2), the relationship of n-C 7 , MCH and DMCP and compound specific carbon isotope of C 6 -C 7 compounds, the gas in the O1m5 reservoir shares the same origin with that in the P1x, P1s reservoirs, the natural gas in Ordovician weathered crust reservoir and Permian sandstone reservoir sourced from coal measures in Carboniferous and Permian.

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Compound-specific isotope analysis as a tool for characterizing mixed oils: an example from the West of Shetlands area

Cited by 77 publications

References 15 publications

Combining biomarker and bulk compositional gradient analysis to assess reservoir connectivity

Combining biomarker and bulk compositional gradient analysis to assess reservoir connectivity

Carbon and hydrogen isotopic compositions of n -alkanes as a tool in petroleum exploration

Characterization of Low Molecular Weight Hydrocarbons in Jingbian Gas Field and its Application to Gas Sources Identification

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