Stable carbon isotope evidence for the origin of C28 steranes in lacustrine source rocks from the Qikou Sag, Bohai Bay Basin, Eastern China

2020 ◽  
Vol 145 ◽  
pp. 104028
Author(s):  
Yongdong Zhang ◽  
Yongge Sun ◽  
Jianping Chen
Keyword(s):  
Carbon Isotope ◽  
Eastern China ◽  
Stable Carbon Isotope ◽  
Source Rocks ◽  
Bohai Bay ◽  
Stable Carbon ◽  
Bohai Bay Basin ◽  
Qikou Sag ◽  
Isotope Evidence

Hydrocarbon generation and evolution of the source rocks of the lower Es3 and upper Es4 members of the Shahejie Formation in the Niuzhuang Sub-sag, Jiyang Depression, Bohai Bay Basin, eastern China

2018 ◽  
Vol 6 (4) ◽  
pp. SN11-SN21
Author(s):  
Zhenkai Huang ◽  
Maowen Li ◽  
Quanyou Liu ◽  
Xiaomin Xie ◽  
Peng Liu ◽  
...  
Keyword(s):  
Activation Energy ◽  
Eastern China ◽  
Source Rocks ◽  
Bohai Bay ◽  
Hydrocarbon Generation ◽  
Bohai Bay Basin ◽  
Jiyang Depression ◽  
Generation Threshold ◽  
Oil Generation ◽  
Shahejie Formation

Systematic organic petrology and geochemistry analyses have been conducted in the source rocks of the lower Es3 and upper Es4 members of the Shahejie Formation in the Niuzhuang Sub-sag, Jiyang Depression, Bohai Bay Basin, eastern China. The results indicate that the main organic types of shale and nongypsum mudstone in the lower Es3 and upper Es4 member are I-II1 kerogen, and the predominant ([Formula: see text]) activation energy frequencies range from 57 to [Formula: see text]. The similar distribution characteristics in the two source rocks indicate that they have a similar hydrocarbon maturation process. An extensive pyrolysis analysis indicates that the source rocks of the upper Es4 member do not have an obvious double peak hydrocarbon generation model. Previous studies indicate that the hydrocarbon index peak at a depth of 2500–2700 m is affected by migrating hydrocarbon. Major differences are not observed in the hydrocarbon generation and evolution process of the shale and nongypsum mudstone. The primary oil generation threshold of the lower Es3 and upper Es4 members is approximately 3200 m, and the oil generation peak is approximately 3500 m. The activation energy distribution of the gypsum mudstone of the upper Es4 member is wider than that of the shale and nongypsum mudstone, and lower activation energies account for a larger proportion of the activation energies. The above factors may lead to a shallower oil generation threshold for gypsum mudstone compared with that for shale and nongypsum mudstone.

scholarly journals Biomarker Ratios and Stablecarbon Isotopes to Describe Crude Oils Characteristics in the Murzuq Basin (Libya)

2019 ◽  
pp. 1-12
Author(s):  
S. Aboglila ◽  
A. Abdulgader ◽  
A. Albaghdady ◽  
O. Hlal ◽  
E. Farifr
Keyword(s):  
Mass Spectrometry ◽  
Carbon Isotope ◽  
Isotope Ratio ◽  
Stable Carbon Isotope ◽  
Source Rocks ◽  
Bacterial Degradation ◽  
Gas Chromatography Mass Spectrometry ◽  
Crude Oils ◽  
Stable Carbon ◽  
Lower Palaeozoic

This present paper includes a detailed evaluation of specific biomarkers together with stable carbon isotope (δ13C) by gas chromatography-mass spectrometry (GC–MS) and Gas Chromatograph–Isotope Ratio Mass Spectrometry (GC–IR–MS). Eight crude oil samples were collected from the A, B, H (east) and H (west) Fields, located in the Murzuq Basin, Libya. Stable Carbon isotope data (δ13C) together with biomarker ratios data of individual hydrocarbons, n-alkanes, isoprenoids, terpenes, hopanes, steranes and aromatic have been determined in crude oils to delineate their bacterial degradation, source facies, organic matter precursors, depositional conditions and a variation of maturation. Based on source-specific parameters including n-C19 alkane, % C27S, %C28S, %C29S, %C23TT, %C30αβ, %rC28, DBT/P, CPI, Pr/Ph, Ts/Tm, dh 30/h 30, 1 MN, 2 MN,         26-27 DMN, 15 DMN, 236 TMN, 146-135 TMN, 125 TMN, 136 TMN ratios and δ13C‰ of saturates and aromatics fractions. Such oils showed non-biodegradation, n-C19 peak proved oils generated from a Lower Palaeozoic source rocks as emphasizedvian-C19 peak, the dominance of C29steranes over C27 and C28 with light Carbon isotope ratio (δ13C‰) values. The abundances of isosterane C29, C27, C28.Tricyclohexaprenol and bacteriohopane polyols and aminopolyols, recommended as mixture bioprecursors of tricyclic terpenes and hopanes, furthermore regular sterane ratio gives values characteristic of Lower Palaeozoic marine source rocks and holding green algae and most likely a quantity of contribution from acritarchs. Carbon preference indices (CPIs)>0.9 pointed to an anoxic deposition, dibenzothiophene to phenanthrene (DBT/Prange 0.49 - 0.58) recommend a siliciclastic source rather than carbonate and/or evaporate saline deposition. The ratios of CPIs, pristane/n-C17 and phytane/n-C18, n-alkanes (C16 to C22) against (C23 to C33), Ts/Tm, C30diahopane/C30hopane, methylnaphthalene, dimethyl naphthalene and trimethyl naphthalene indicated that the oils analysed are mature except the B Field oil being slightly less mature than the A, H (east) and  H (west) Fields oils.

scholarly journals Petroleum Geochemistry Regional Study of Murzuq Basin: Insights from Biomarkers Characteristic, Stable Carbon Isotope and Environmental Characterization

2020 ◽  
Vol 4 (1) ◽  
pp. 1-14
Author(s):  
Aboglila S
Keyword(s):  
Carbon Isotope ◽  
Vitrinite Reflectance ◽  
Stable Carbon Isotope ◽  
Source Rocks ◽  
Crude Oils ◽  
Type I ◽  
Stable Carbon ◽  
Potential Source ◽  
Geochemical Parameters ◽  
Rock Eval

This search aims to apply developed geochemical methods to a number of oils and source rock extracts to better establish the features of ancient environments that occurred in the Murzuq basin. Geochemical and geophysical approaches were used to confirm further a source contribution from other Paleozoic formations to hydrocarbon accumulations in the basin. One hundred and forty rock units were collected from B1-NC151, D1-NC174, A1-NC 76, D1-NC 151, F1-NC58, A1-NC 186, P1-NC 101, D1-NC 58, H1-NC58 and A1-NC58 wells. Seven crude oils were collocated A1-NC186, B1-NC186, E2-NC101, F3-NC174, A10-NC115, B10-NC115 and H10-NC115 wells. A geochemical assessment of the studied rocks and oils was done by means of geochemical parameters of total organic carbon (TOC), Rock-Eval analysis, detailed-various biomarkers and stable carbon isotope. The TOC values from B1-NC151 range 0.40% to 8.5%, A1-NC186 0.3% and 1.45, A1-NC76 0.39% to 0.74%, D1-NC151 0.40% to 2.00% to F1-NC58 0.40% to 1.12%. D1_NC174 0.30% to 10 %, P1-NC101 0.80% to 1.35%, D1-NC58 0.5% to 1.10%, H1-NC58 0.20% to 3.50%, A1-NC58 0.40% to 1.60%. The categories of organic matter from rock-eval pyrolysis statistics point to that type II kerogen is the main type, in association with type III, and no of type I kerogen recognized. Vitrinite reflectance (%Ro), Tmax and Spore colour index (SCI) as thermal maturity parameters reflect that the measured rock units are have different maturation levels, ranging from immature to mature sources. acritarchs distribution for most samples could be recognized and Palynomorphs are uncommon. Pristane to phytane ratios (> 1) revealed marine shale to lacustrine of environmental deposition. The Stable carbon isotope ( δ 13 C) values of seven rock-extract samples are -30.98‰ and -29.14‰ of saturates and -29.86‰ to -28.37‰ aromatic fractions. The oil saturate hydrocarbon fractions range between -29.36‰ to -28.67‰ and aromatic are among -29.98 ‰ to -29.55 ‰. The δ 13 C data in both rock extractions and crude oils are closer to each other, typical in sign of Paleozoic age. It is clear that the base of Tanezzuft Formation (Hot shale) is considered the main source rocks. The Devonian Awaynat Wanin Formation as well locally holds sufficient oil prone kerogen to consider as potential source rocks. Ordovician Mamuniyat Formation shales may poorly contain oil prone kerogen to be addressed in future studies. An assessment of the correlations between the oils and potential source rocks and between the oils themselves indicated that most of the rocks extracts were broadly similar to most of the oils and supported by carbon stable isotope analysis results.

scholarly journals Stable carbon isotope evidence for the microbial origin of C14C18 n-alkanoic acids in soils

1995 ◽  
Vol 23 (9) ◽  
pp. 849-852 ◽  
Author(s):  
Éric Lichtfouse ◽  
Gersende Berthier ◽  
Sabine Houot ◽  
Enrique Barriuso ◽  
Valérie Bergheaud ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Stable Carbon Isotope ◽  
Stable Carbon ◽  
Microbial Origin ◽  
Alkanoic Acids ◽  
Isotope Evidence

Geochemical characteristics and source of natural gases in the northern Jizhong Subbasin, Bohai Bay Basin, eastern China

2020 ◽  
Author(s):  
Nian Liu ◽  
Nansheng Qiu
Keyword(s):  
Carbon Dioxide ◽  
Carbon Isotope ◽  
Eastern China ◽  
Geochemical Characteristics ◽  
Bohai Bay ◽  
Bohai Bay Basin ◽  
Organic Matters ◽  
Natural Gases ◽  
Isotopic Compositions ◽  
Shallow Strata

<p>The geochemical characteristics and source of natural gases in the northern Subbasin, Bohai Bay Basin, eastern China are investigated systematically by the chemical components, stable isotopic compositions, noble gases isotopic compositions, and geochemical characteristics of associated oils. The results show that several genetic gases are identified in the study area, including thermogenic gas (sapropelic and humic gas), biogenetic gas (primary and secondary microbial gas) and mixed gas. Gases in the shallow strata (Ed, Es<sub>1</sub>, Es<sub>2</sub>, Es<sub>3 </sub>and some Es<sub>4</sub> samples) are mainly oil-associated gases, whereas the gases in the deep strata (some Es<sub>4</sub> samples, C-P and O) are mainly coal-derived gases and mixed-source gases. Some microbial gases including primary and secondary microbial gases can be identified in shallow Es<sub>1 </sub>and Es<sub>3 </sub>reservoirs. The carbon dioxide reduction under anaerobic conditions may be responsible for the anomalously heavy carbon isotope in carbon dioxide and light carbon isotope in methane in the biodegradation gases from the shallow strata (<1900 m), whereas carbon dioxide with heavy isotope compositions in the deeply buried Ordovician reservoirs may be the production of strong acids react with carbonate rocks during acidification and fracturing. The oil-associated gases in shallow strata are derived primarily from the Paleogene Es<sub>3</sub> and Es<sub>4</sub>+Ek bearing sapropelic organic matters, whereas the coal-derived gases in the relatively deep reservoirs are mainly derived from the Paleozoic C-P coal-bearing source rocks and mixed organic matters in Es<sub>4</sub>+Ek. In addition, the dry gas (secondary cracking gas) in deep to ultra-deep carbonate reservoir may be the potential and favorable exploration field.</p>

scholarly journals Stable Carbon Isotope Evidence for Neolithic and Bronze Age Crop Water Management in the Eastern Mediterranean and Southwest Asia

PLoS ONE ◽  
2015 ◽  
Vol 10 (6) ◽  
pp. e0127085 ◽  
Author(s):  
Michael P. Wallace ◽  
Glynis Jones ◽  
Michael Charles ◽  
Rebecca Fraser ◽  
Tim H. E. Heaton ◽  
...  
Keyword(s):  
Water Management ◽  
Bronze Age ◽  
Carbon Isotope ◽  
Eastern Mediterranean ◽  
Stable Carbon Isotope ◽  
Southwest Asia ◽  
Stable Carbon ◽  
Crop Water ◽  
Isotope Evidence
Sign in / Sign up

Export Citation Format

Share Document