Two case studies of oil-source correlation: Neo-Mesoproterozoic oil seeps and Paleogene oil pools in the north margin of the Bohai Gulf Basin | Macquarie University ResearchOnline

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Two case studies of oil-source correlation: Neo-Mesoproterozoic oil seeps and Paleogene oil pools in the north margin of the Bohai Gulf Basin

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Title: Two case studies of oil-source correlation: Neo-Mesoproterozoic oil seeps and Paleogene oil pools in the north margin of the Bohai Gulf Basin
Title: Neo-Mesoproterozoic oil seeps and paleogene oil pools in the north margin of the Bohai Gulf Basin
Title: 渤海湾盆地北缘中新元古界油苗和古近系原油的油源研究
Related: Australasian Digital Theses
Publisher: Australia : Macquarie University
Date: 2011
Author/Creator: Mu, Guoyan
Description: Thesis (PhD)--Macquarie University, Faculty of Science, Dept. of Earth and Planetary Sciences, 2011.
Description: Bibliography: p. 166-177.
Description: 第1章前言 -- 第2章试验装置和测试分析方法的建立 -- 第3章燕山地区中新元古界油源研究 -- 第4章辽河西部凹陷古近系油源精细对比 -- 第5章结论.
Description: Oil-source correlations are based on the concept that certain compositional parameters of migrated oil do not differ significantly from those of bitumen remaining in the source rocks. This similarity though heritage can range from bulk properties, such as stable carbon isotope compositions, to individual compound ratios. Detailed oil-source rock correlations provide important information on the origin and possible paths of migration of oils that lead to additional exploration plays, and are helpful for reconstructing petroleum reservoir accumulation histories and fuel resource assessments. Biomarkers play a critical role in geochemical correlations. However, for Precambrian organic matter, there are significant difficulties doing oil-source rock correlations because of the likely high thermal maturity of the sedimentary organic matter, the sometimes low organic matter abundance, the small amount of geochemical information, and problems of contamination and over-printing. For highly mature exploration areas, attempts to objectively analyse the geochemical characteristics of crude oils based on a large geochemical data set, and how to evaluate source rocks more accurately, so as to improve the understanding of reservoir relationships and predicting petroleum resource are becoming more urgent problems at the moment. In this thesis, two representative fields were selected, the Neo-Mesoproterozoic sequence of the Yanshan Region and the highly mature exploration area of the Western Depression of the Liaohe Basin, in order to specifically answer correlation and other geochemical problems. -- The first of these case studies involves the marine sediments of the Yanshan Region which are some of the least deformed and least thermally mature hydrocarbon-bearing Neo-Mesoproterozoic sequences in China. The oil shows and seeps are mainly distributed in the reservoir sequences of the Xiamaling Formation (ca.1368 Ma), Tieling Formation and Wumishan Formation, which are probably derived either from the underlying organic-rich Hongshuizhuang Formation, or from kerogen within the Gaoyuzhuang Formation, as there are no known source rocks in the section. The 27 m thick mudstone of the Hongshuizhuang Formation has total organic carbon (TOC) levels of up to 5.5% and eqRomarine of about 1.7%. The other potential source rock (dolomite from the Gaoyuzhuang Formation) has TOC levels around 2.7% with 2.2% eqRomarine. Three outcrop source rocks were sampled from these two sequences and kerogen catalytic hydrogenation was performed in order to get more geochemical information on these high thermal maturity samples. Another two source rocks from drilling cores using standard solvent extraction have been analysed by gas chromatography-mass spectrometry (GC-MS). As for the either contaminated or biodegraded oil seeps, two samples rich in oil-bearing fluid inclusions (FI), (1) a limestone sample from the Tieling Formation, and (2) a bitumen sandstone from the Xiamaling Formation, were chosen for detailed analyses by the Molecular Composition of Inclusions (MCI) protocols. In addition, twenty samples from the reservoirs have been sequentially extracted as a supplement to the MCI analysis.
Description: Hopanes, tricyclic terpanes and bicyclic sesquiterpanes are abundant in the FI oils and most samples from reservoir sequences, and their ratios, such as lower Pr/Ph ration, higher Grammacerane Index and higher C₂₄ tetracyclic terpane and C₁₄ biocyclic terpane suggest dominantly microbial input under a reductive deep water environment. However, steranes were below detection limit in the FI oils, and also in the source rocks of the Hongshuizhuang Formation which was deposited under anoxic conditions. The distribution of monomethylalkanes in the reservoir sequence FI oils and most reservoir extracts correlate well with the organic-rich marine Hongshuizhuang Formation and is different from the Gaoyuzhuang Formation. Maturity parameters based on biomarkers, alkanes and aromatic hydrocarbons indicate that the FI oils and most reservoir sequential extracts have reached the peak stage of the oil generation window, indicating that the Hongshuizhuang Formation is the main source rock of this area. Furthermore, the particular 13α(H)-tricyclic terpanes only detecte in the FI oils, most reservoir extracts and the Hongshuizhuang Formation also supports this deduction. However, some reservoir sequential extracts contain different geochemical signatures, including higher 2α(H)-methylhopanes, less abundant 3β-methylhopanes and rich steranes, which indicate cyanobacterial and algal input. Associated with other parameters, such as lower Gammacerane Index, lower ration of Pr/Pr, higher Rc(%) (based on MP₁) and C₃₀ αβ/(αβ+βα) ratios, these data suggest that these extracts are derived from the Gaoyuzhuang Formation, which was deposited in a shallow water toxic environment and which had experienced high thermal evolution. Following these oil-source correlations, and combined with geological background, the history of this palaeo-oil reservoir accumulation has been reconstructed. In particular, the region received early petroleum charge that was possibly from the Gaoyuzhuang Formation source rock before dolerite intrusion (ca. 1327Ma). A late oil charge was happened during Yanshan movement when the Hongshuizhuang Formation source rock generated mature oil and expelled. This has more significant oil contribution in terms of large oil generation potential and tectonic dynamic.
Description: The second case study was on Paleogene age sediments of the Western Depression of the Liaohe Basin, which are currently in mature production. The objective of this case is systematically and objectively to interpret large volumes of multivariate geochemical data and correlate crude oils and source rocks. A suite of samples consisting of seventy-five crude oils and fifty-six reservoir sandstones, thus have been analysed for biological marker compounds by GC-MS, and twenty-nine of these samples were also selected for stable carbon isotopic analysis. Combined with the former geochemical database (~220 samples), crude oils were correlated into three genetic families (I, II, III), mainly based on the Gammacerane Index, Pr/Ph, C₂₄ tetracyclic terpane/tricyclics terpanes and ααα20R C₂₈/C₂₉ sterane ratios. These samples were then subdivided them into three groups (A, B, C) based on thermal maturity (αααC₂₉ 20S/(20S+20R) steranes) and level of biodegradation (25-norhopanes). -- The source rocks (one hundred sixty-eight samples) were analysed using a series of geochemical and petrological experiments. The geochemical signatures were then evaluated in the sequence stratigraphic framework and compared with the oil types respectively. Generally, Family I oils were sourced from rocks containing algal and bacterial input under reducing and probably hypersaline environments, and are mainly distributed in the north of the depression (SQ₁, SQ₂). The Family II oils were sourced from rocks containing algal and higher plant input under reducing and brackish conditions, and are distributed in the mid-south of the depression (SQ₃, SQ₄). The Family III oils were sourced from rocks containing mainly alga input deposited under reducing, freshwater environments, and are distributed on the southwest of the depression (SQ₄, SQ₆). This information on the correlation of oil groups and source rocks will be crucial in understanding the Western Depression petroleum system and for guiding petroleum resource assessment and future oil exploration.
Description: Mode of access: World Wide Web.
Description: x, 202 p. ill. (some col.), col. maps
Subject Keyword: Petroleum -- Geology -- China -- Yanshan Region
Subject Keyword: Petroleum -- Geology -- China -- Bohai Bay Basin
Subject Keyword: Geochemistry -- China -- Yanshan Region
Subject Keyword: Geochemistry -- China -- Bohai Bay Basin
Subject Keyword: Geology, Stratigraphic
Subject Keyword: Geology, Stratigraphic
Subject Keyword: Stratigraphic correlation -- China -- Yanshan Region
Subject Keyword: Stratigraphic correlation -- China -- Bohai Bay Basin
Subject Keyword: Yanshan Region
Subject Keyword: Neo Mesoproterozoic
Subject Keyword: molecular composition of inclusion
Subject Keyword: Paleogene
Subject Keyword: Western Depression of the Liaohe Basin
Subject Keyword: oil source correlation
Resource Type: Thesis PhD
Organisation: Macquarie University. Dept. of Earth and Planetary Sciences

Identifier: http://hdl.handle.net/1959.14/183100
Identifier: 1603141
Language: chi
Rights: Copyright disclaimer: http://www.copyright.mq.edu.au
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