1,721,001 research outputs found
Unmixing of mixed oil using chemometrics
No full textIn this study, chemometrics was used to unmix a set of oil samples that had been mixed in the laboratory using three end-member oils. It was shown that the concentrations of individual compounds in the mixed oil varied linearly with the fractional contribution of each end-member oil. However, biomarker ratios in the mixed oils varied non-linearly with the amount of each end-member oil. This study demonstrates that concentrations and ratios of biomarkers yield different results when de-convoluting mixed oils. Concentrations of biomarkers are therefore more suitable than the biomarker ratios for unmixing mixed oils. Alternating least squares of biomarker concentrations (ALS-C) provides an excellent way to calculate the number, proportions, and compound compositions of the end-members in mixed oil samples. The ALS-C results are accurate, regardless of whether end-member oils are included in the sample set. The biomarker ratios of end-member oils cannot be directly obtained by ALS, but can instead be calculated using related compound concentrations computed by ALS-C. This method should be applied and verified widely using actual geochemical data. (C) 2015 Elsevier Ltd. All rights reserved
De-convoluting crude oil mixtures from Palaeozoic reservoirs in the Tabei Uplift, Tarim Basin, China
No full textGeochemical characteristics of 61 crude oil samples collected from Palaeozoic reservoirs in the Tarim Basin (60 from the Tabei Uplift and one from the Tazhong Uplift) were analyzed. The samples proved to be mixed oils of different maturity from diverse source rocks. Concentrations of 40 biomarkers and carbon isotopic compositions for the whole oils were analyzed by alternating least squares (ALS) regression to de-convolute the mixtures. Three endmember (EM) oils were identified. EM1 is the minimum contributor to the mixed oils, accounting for less than 10% of most oils. EM1 originated from Cambrian-Lower Ordovician source rocks in the early to peak oil window stage and experienced two phases of mixing and biodegradation. EM2 is the secondary contributor with proportions ranging from 10% to 40% in most oil samples. EM2 originated from Middle-Upper Ordovician source rocks at the early oil generation stage and underwent two phases of mixing and one stage biodegradation in the reservoirs. EM3 is the major contributor to most samples with proportions ranging from 13% to 95%. EM3 was generated from Middle-Upper Ordovician source rocks at the late oil generation stage and mixed with earlier emplaced mixtures in the reservoirs. The final mixtures that were not biodegraded are currently exploited from Palaeozoic reservoirs in the Tabei Uplift. Biomarkers in the crude oils reveal mixed characteristics, including evidence for two phases of oil charge and severe biodegradation. (C) 2016 Elsevier Ltd. All rights reserved
Paleoclimate, nutrient supply and lacustrine source rocks formation in Songliao Basin, China
No full textShallow groundwater surrounding the Likeng landfill, Guangzhou, China - major ions and elements indicating the contamination sources
No full textAn investigation of groundwater contamination around the Likeng landfill, Guangzhou, was carried out. Major ions and elements of 34 groundwater samples were measured, and the Piper trilinear diagram and expanded Durov diagram were used to analyze the chemical types and hydrogeochemical processes of the groundwater. End Member Mixing Analysis was used to find the types and sources of pollutants. The results show that the hydro-geochemical process was mainly mixing and ion exchange; the shallow groundwater around the Likeng landfill was contaminated mainly by both anthropogenic/agricultural sources and leachate pollution. There are different types of major ions, hydro-chemical processes and distributions for the two pollution sources
Adsorption of mudstone source rock for shale oil - Experiments, model and a case study
No full textInorganic minerals were separated from mudstone and shale to investigate their oil adsorption potential. A conceptual model was developed to reconstruct the oil adsorption capacity of underground mudrock/shale by combining adsorption and organic matter swelling data. The predictions for the free hydrocarbon oversaturation sorption zones in the Well NY1 profile were taken as a case study. The results suggest that the best depth for the shale oil prospect of the Es4s member strata lies between 3400 and 3600 m in the Dongying Depression. Hydrocarbon starvation zones occur mainly at a depth of < 3400 m, where both the maturity and the extent of oil conversion of organic matter are relatively low, while the sorption capacity of mudstone and shale rocks is by comparison high and the exploration risk is greater. (C) 2015 Elsevier Ltd. All rights reserved
Kinetics of oil group-type generation and expulsion: An integrated application to Dongying Depression, Bohai Bay Basin, China
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