Combining biomarker and bulk compositional gradient analysis to assess reservoir connectivity

Pomerantz, Andrew E.; Ventura, G. Todd; McKenna, Amy M.; Canas, Jesus Alberto; Auman, John; Koerner, Kyle Ross; Curry, David J.; Nelson, Robert K.; Reddy, Christopher M.; Rodgers, Ryan P.; Marshall, Alan G.; Peters, Kenneth E.; Mullins, Oliver C.

doi:10.1016/j.orggeochem.2010.05.003

Cited by 68 publications

(87 citation statements)

References 57 publications

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“…Here, both FT-ICR and Orbitrap data were recalibrated using the automatic recalibration feature on the Composer software (Sierra Analytics). 1 After recalibration against ∼50 such peaks, the resulting mass accuracy of FT-ICR and Orbitrap are nearly identical: rms error of 1.1 ppm and mean error of 0.1 ppm over all assigned peaks. This result is demonstrated in Figure 2 by the very similar measured m/z values for peaks present in both the FT-ICR and the Orbitrap spectra.…”

Section: ' Experimental Sectionmentioning

confidence: 93%

Orbitrap Mass Spectrometry: A Proposal for Routine Analysis of Nonvolatile Components of Petroleum

et al. 2011

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High-resolution mass spectrometry can provide a detailed fingerprint of the composition of the nonvolatile fraction of petroleum. That analysis is typically performed using Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry, which offers greater mass resolution than any other mass analyzer. While high resolution is desirable for complex mixtures, such as petroleum, the high costs associated with FT-ICR limit its use to a small number of research laboratories, limiting the impact of the measurement relative to more accessible techniques. Here, we explore whether there is a role for other high-resolution mass analyzers to complement FT-ICR. One such high-resolution mass analyzer is the LTQ Orbitrap XL, which presents significantly lower costs relative to typical FT-ICR instruments. The Orbitrap mass analyzer provides mass resolution inferior to the modern FT-ICR instrument but still sufficient to assign molecular formulas to individual components present in mixtures, especially those components present in relatively high abundance. Indeed, the resolution of the LTQ Orbitrap XL is comparable to that obtained by FT-ICR instruments 1 decade ago, at which time FT-ICR was being used successfully to fingerprint petroleum. Here, we demonstrate successful application of the Orbitrap to resolve and identify >1000 of the more abundant molecular formulas in the negative ion electrospray ionization mass spectrum of a petroleum sample. These results are compared to the 9.4 T FT-ICR analysis of the same sample (published previously; Pomerantz, A. E.; Ventura, G. T.; McKenna, A. M.; Cañas, J.; Auman, J.; Koerner, K.; Curry, D.; Nelson, R. K.; Reddy, C. M.; Rodgers, R. P.; Marshall, A. G.; Peters, K. E.; Mullins, O. C. Combining biomarker and bulk compositional gradient analysis to assess reservoir connectivity. Org. Geochem. 2010, 41, 812À821), and in this analysis, both the compositional fingerprints and conclusions derived from those fingerprints are essentially the same for the FT-ICR and Orbitrap data. Setting up and operating a LTQ Orbitrap XL mass spectrometer presents significantly lower initial and continuing costs compared to setting up and operating a 9.4 T FT-ICR, and this difference may make the Orbitrap accessible to laboratories for which FT-ICR is cost-prohibitive. Although several valuable high-resolution mass spectrometric analyses require the extremely high resolution of FT-ICR, we propose Orbitrap mass spectrometry as a method for routine analysis of the composition of the more abundant species in the nonvolatile and polar fraction of petroleum. Extending the realm of high-resolution mass spectrometry from a limited research environment to routine analysis would increase the utility of the technique and the impact of fundamental research regarding mass spectrometry of petroleum.

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Section: ' Experimental Sectionmentioning

confidence: 93%

Orbitrap Mass Spectrometry: A Proposal for Routine Analysis of Nonvolatile Components of Petroleum

et al. 2011

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“…The explanation in this case was that the first charge occurred when the reservoir temperature was less than 80 °C, and extensive biodegradation of this oil occurred (leading to formation of 25-horhopanes). [23] Subsequently the reservoir underwent subsidence and heated beyond 80 °C thereby causing paleopasteurization of the reservoir. Subsequent to this event, a further charge of oil into the reservoir occurred accounting for the presence of n-alkanes in the reservoir crude oil.…”

Section: A Simple Diffusion Model For Biodegradationmentioning

confidence: 99%

“…[23] Thus sufficient time had passed to overcome transients of biodegradation and multiple charges of hydrocarbon into the reservoir for equilibration to prevail. [23] The FHZ EoS with nanoaggregates was also shown to apply to a large asphaltene gradient produced in a centrifugation experiment of a live (gas containing) black oil. [24] The FHZ EoS with clusters has been shown to account for an asphaltene gradient of a factor of 10 in a 50 meter column of heavy oil over a 100 kilometer circumferential rim of an anticlinal oilfield.…”

Section: Introductionmentioning

confidence: 99%

Diffusion Model Coupled with the Flory–Huggins–Zuo Equation of State and Yen–Mullins Model Accounts for Large Viscosity and Asphaltene Variations in a Reservoir Undergoing Active Biodegradation

Zuo

Jackson²,

Agarwal³

et al. 2015

Energy Fuels

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A very large monotonic variation of asphaltenes and viscosity has been measured by downhole fluid analysis (DFA) in crude oils in five-stacked sandstone reservoirs in the northern part of the Barmer Basin, northwest India, undergoing active biodegradation; each of the five-layered sand bodies shows overlaying fluid gradients with depth providing replicate validation of the measurements. Fluid data from four wells across the field shows that the gradients are uniform across the formation. The crude oil in the upper half of the oil column exhibits an equilibrium distribution of asphaltenes matching predictions of the Flory-Huggins-Zuo Equation of state (FHZ EoS) with the gravity term only using asphaltene nanoaggregates of the Yen-Mullins model. However, the bottom half of the reservoir reveals a large asphaltene gradient approximately three times larger than the equilibrium predictions from the FHZ EoS. This increase in asphaltenes creates a very large (8x) viscosity gradient and is a major production concern. In addition, these shallow reservoirs are undergoing active biodegradation at temperatures of 55 °C to 61 °C.A simple diffusive model coupled with the FHZ EoS is shown to account for the entire observed asphaltene distribution in each of the five sand layers. Alkanes (and some aromatics) are rapidly consumed at the oil-water contact at the base of the oil column. The rate-limiting step is the diffusion of these compounds to the oil-water contact. The loss of these oil components decreases the oil volume yielding an increase in asphaltene concentration and a significant increase in viscosity. The limited geologic time of the oil in the reservoir limits the vertical extent of the diffusive process accounting for the observation of asphaltene equilibrium at the top of the column. Specifically, petroleum system modeling of this basin indicates that the oil commenced undergoing biodegradation approximately 50 million years ago, and this duration matches the analysis using the diffusion model plus the FHZEoS. Gas chromatography applied to the oils from the top to the bottom of the oil column provides detailed compositional confirmation of the diffusive mechanism proposed. In particular, all measured compositional properties of the oil column are shown to be consistent with this simple diffusive model. The ability to account for asphaltene and viscosity variations in the five stacked sand layers with a simple diffusive model coupled with the FHZ EoS and the Yen-Mullins model provides a robust model for improving efficiency of reservoir engineering and oil production.

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“…Figure 3 shows an expanded view of this region of the GCxGC chromatogram for two crude oils from a reservoir in the Llanos basin. [Bartha et al, 2015] Other studies have combined DFA and GCxGC for a variety of purposes including reservoir compartmentalization [Mullins, 2008] and connectivity, [Mullins, 2008;Pomerantz et al, 2010;Dong et al, 2014;Forsythe et al, 2015] multiple charging [Pomerantz et al, 2010] and analysis of tar mat formation [Forsythe et al, 2015]. This combination is effective for evaluation of many reservoir concerns.…”

Section: Introductionmentioning

confidence: 99%

Integrating comprehensive two-dimensional gas chromatography and downhole fluid analysis to validate a spill-fill sequence of reservoirs with variations of biodegradation, water washing and thermal maturity

Forsythe

Martin

Santo

et al. 2017

Fuel

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Optimization of crude oil production depends heavily on crude oil composition and its variation within individual reservoirs and across multiple reservoirs. In particular, asphaltene content has an enormous impact on crude oil viscosity and even the economic value of the fluids in the reservoir. Thus, it is highly desirable to understand the primary controls on crude oil composition and asphaltene distributions in reservoirs. Here, a complex oilfield in the North Sea containing six separate reservoirs is addressed. The crude oil is believed to have spilled out of deeper reservoirs into shallower reservoirs during the overall reservoir charging process. Asphaltene content is measured in-situ through downhole fluid analysis and is generally consistent with a spill-fill sequence in reservoir charging. Detailed compositional analysis of crude oil samples by comprehensive two-dimensional gas chromatography (GC×GC) is used to determine the extent and variation among the reservoirs of water washing, biodegradation and thermal maturity. Increased biodegradation and water washing in the shallower reservoirs is consistent with a spillfill sequence. The water washing is evidently assisted by biodegradation. Moreover, analyses of four thermal maturity biomarkers show that shallower reservoirs contain less mature oil, again consistent with a spill-fill sequence. The combination of DFA for bulk compositional analysis and GC×GC for detailed compositional analysis with geochemical interpretation is an effective tool for unraveling complex oilfield scenarios.

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Combining biomarker and bulk compositional gradient analysis to assess reservoir connectivity

Cited by 68 publications

References 57 publications

Orbitrap Mass Spectrometry: A Proposal for Routine Analysis of Nonvolatile Components of Petroleum

Orbitrap Mass Spectrometry: A Proposal for Routine Analysis of Nonvolatile Components of Petroleum

Diffusion Model Coupled with the Flory–Huggins–Zuo Equation of State and Yen–Mullins Model Accounts for Large Viscosity and Asphaltene Variations in a Reservoir Undergoing Active Biodegradation

Integrating comprehensive two-dimensional gas chromatography and downhole fluid analysis to validate a spill-fill sequence of reservoirs with variations of biodegradation, water washing and thermal maturity

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