A research into the crude oil geochemistry and oil-source correlation by means of gas chromatography and gas chromatography–mass spectrometry: a case study of the Laizhou Bay Sag, Bohai Bay Basin, China

Yu, Qilin; Xu, Guoce; Liang, Hongda; Xu, Fanghao; Liang, Jiaju; Wang, Deying

doi:10.1007/s12517-019-4815-0

Cited by 1 publication

(2 citation statements)

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“…Therefore, family C oils, typically characterized by high gammacerane, should originate from source rocks developed in a hypersaline water depositional system, while family A samples with low gammacerane should be attributed to a freshwater depositional system developed in the depression. Similar two end-member oils were also noticed by Yu et al…”

Section: Resultssupporting

confidence: 87%

“…Typical biomarkers revealed in the oils from the Kenli10-1 oilfield indicate a source from freshwater depositional environments. , More recently, a set of high-sulfuric oils were observed in the southern part of the depression, suggesting a source from saline water depositional environments likely developed in the Es4 member within the southern sag . Typical biomarker compositions in the oils have been successfully applied to oil-source correlation and validated two end-member systems in the depression. , Generally, crude oils were revealed to be widespread in the depression with reservoirs vertically distributed in the Minghuazhen (Nm), Guantao (Ng), Dongying (Ed), Shahejie (Es), and Kongdian (Ek) formations. The oils produced from different formations show great variability in physical properties with API (American Petroleum Institute) gravity ranging in 14–35° and viscosity changing in 6.5–2283 mPa·s.…”

Section: Introductionmentioning

confidence: 99%

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Chemometric Classification of Oil Families in the Laizhouwan Depression, Bohai Bay Basin, Eastern China

Tan¹,

Guo

Huang

2021

ACS Omega

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A suite of oil-sand bitumen and crude oil samples, collected from the Laizhouwan depression, Bohai Bay basin, were geochemically investigated for molecular compositions. Three oil families (A, B, and C) were classified by hierarchical cluster analysis (HCA) and principal component analysis on nine typical biomarker ratios. Typically, family A oils are characterized by relatively low values of gammacerane/C 31 homohopane 22R (G/H31, 0.13−0.76) and C 35 /C 34 homohopane (H35/H34, 0.39−0.78), suggesting a source from freshwater depositional environments. In contrast, family C oils show a relatively high G/H31 (2.49−5.41) and H35/H34 (1.43−2.45) ratios, indicating a source from hypersaline water depositional environments. Family B oils display ratios of G/H31 and H35/H34 inbetween the range of families A and C, suggesting mixed origin. In addition, family A oils can be further classified into four subfamilies (A1, A2, A3, and A4) and family B oils into two subfamilies (B1 and B2) by HCA. The A1 oils characterized by a high C 24 tetracyclic terpane/C 26 tricyclic terpane (TeT24/ TT26) ratio (1.02−1.39) are mainly distributed in the northeast, B1 oils characterized by relatively low TeT24/TT26 ratio are in the west, and A2, A3, and A4 oils with an intermediate TeT24/TT26 ratio are in the center of the depression. Oils in well L16-1-2 in the southern depression, however, show vertical variations with family C oils in the deeper reservoirs, subfamily B2 oils in the shallower reservoirs, and subfamily A4 oils in the middle-depth reservoirs. Based on the biomarker compositions, at least three oil charges were indicated: family C oils are likely sourced from the Es4 rock in the southern sag, B2 oils may be a mixture of family C with family A oils, and A4 oils without biodegradation influence may be the latest charge derived from the Es3 source rock in the northern sag. The oil families and/or subfamilies with typical genetic affinities, as well as the regular occurrence in different blocks, may indicate two major petroleum systems or multiple subsidiary oil systems existing in the Laizhouwan depression.

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Section: Resultssupporting

confidence: 87%