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

Author Posting. © The Author(s), 2016. This is the author's version of the work. It is posted here for personal use, not for redistribution. The definitive version was published in Fuel 191 (2017): 538-554, doi:10.1016/j.fuel.2016.11.081.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 spill-fill 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

Ontogeny of the adrenocortical response in an extremely altricial bird

Life history theory predicts that physiological and behavioral responsiveness to stress should be delayed in development until the benefits of heightened reactivity outweigh the costs of potentially chronic glucocorticoid levels. Birds often acquire stress-responsiveness at locomotor independence, however, both stress-responsiveness and locomotor ability are delayed in birds with altricial developmental strategies. Parrots (Psittacidae) are extremely altricial, but it is not known whether they also postpone physiological responsiveness to stress until locomotor independence. We quantified individual variation in baseline and stress-induced plasma corticosterone (CORT) concentrations, the main avian glucocorticoid, in wild green-rumped parrotlets (Forpus passerinus) of Venezuela at four stages of nestling development. Parrotlet neonates are very underdeveloped and compete for parental care among extreme sibling size hierarchies, a competitive scenario that might benefit from early hypothalamic–pituitary–adrenal (HPA) functionality. Nestlings that underwent a standardized restraint stress-treatment showed higher average CORT concentrations compared to baseline in all age groups sampled, and exhibited no evidence of age-related changes in the stress response. This is 2 weeks before locomotor independence and earlier than previously documented for altricial species. Results suggest that precocity of HPA function may be advantageous to growth and survivorship in extremely altricial birds

The Chemistry of Oil and Petroleum Products De Gruyter STEM./ ed. by Merv Fingas.

In English.This first publication devoted to the chemistry of oil and petroleum products covers the broad range of topics from heavy fuel oils, gasoline/diesel fuel, crude oils and (diluted) bitumen to today's research on asphaltenes. Recent methods are summarized and the large new groups of chemicals found in oils are identified as well as described in detail. The work points the way for a more complete understanding of the composition of petroleum.Frontmatter -- About the Editor -- Preface -- Contents -- 1 Introduction to oil chemistry -- 2 Chemical fingerprints and chromatographic analysis of crude oils and petroleum products -- 3 Advances in Fourier transform mass spectrometry forensic tools for naphthenic acid fraction compounds in oil sand environmental samples and crude oil -- 4 Heavy oil resin composition and their influence on asphaltene stability -- 5 Asphaltenes: structures and applications -- 6 Asphaltene equation of state and oilfield reservoirs -- 7 Molecular distributions and geochemical implications of pyrrolic nitrogen compounds in crude oils -- 8 Analysis of petroleum-related samples by soft ionization/high-resolution mass spectrometry -- 9 Non-combustion applications of petroleum chemistry -- 10 Biomarkers in crude oils -- 11 Photooxidation of crude oil: formation, characterization, and fate of oil photoproducts in the environment -- 12 Molecular structure characterization of crude oil and its products by mass spectrometry -- 13 The distillation precipitation fractionation mass spectrometry (DPF-MS) method for molecular profiling of crude oil -- 14 Hyphenated gas chromatography and mass spectrometry techniques for the analysis of crude oil and petroleum products -- List of contributing authors -- Index1 online resource (VIII, 689 p.)