Geochemical characteristics of aromatic hydrocarbons in crude oils from the Linnan Subsag,Shandong Province,China

Abundant aromatic fractions were detected in oils from the Linnan subsag, including aphthalenes, phenanthrenes, triaromatic steroids, biphenyl, fluorenes, dibenzothiophenes, dibenzofuranes, as well as some typical higher plant-sourced compounds, such as pyrene, benzopyrene, fluoranthene, chryaene, benzofluoranthrene, perylene and cadalene. Occurrences of biomarkers indicate that oils from the Linnan subsag are typical terrestrially genetic oils. Developed in the depositional environment is a strong reduction condition typical of brackish-saline lake. Thermal evolution has entered into the mature-high mature stage.     

准噶尔盆地西北缘车排子凸起原油类型与油源

准噶尔盆地西北缘南部红车断裂带- 车排子凸起油气藏众多,原油物理化学性质和地球化学特征十分复杂,原油类型及其来源长期存在很大争议。本文在准噶尔盆地不同时代烃源岩生成原油典型地球化学特征与主要油源判识指标归纳总结的基础上,对红车断裂带- 车排子凸起原油地球化学特征和来源进行系统分析研究,将该区域原油分为五类,其中三类原油分别来源于二叠系湖相烃源岩、中—下侏罗统煤系烃源岩、古近系安集海河组湖相烃源岩,另外两类为混合原油,分别为来源于二叠系湖相烃源岩的生物降解稠油与中—下侏罗统煤系烃源岩生成的正常原油和古近系湖相烃源岩生成的正常原油的混合原油。红车断裂带石炭系—白垩系油藏原油主要来源于沙湾凹陷二叠系湖相烃源岩,车排子凸起东北部春风油田稠油来源于沙湾凹陷二叠系湖相烃源岩;车排子凸起东侧- 红车断裂带西侧新近系沙湾组油藏轻质原油来源于四棵树凹陷古近系湖相烃源岩;车排子凸起中部春光油田白垩系—古近系油藏稠油为二叠系来源稠油和侏罗系正常原油的混合原油,新近系沙湾组油藏稠油为二叠系来源稠油与新近系正常原油的混合原油;车排子凸起西部石炭系—古近系油藏轻质原油来源于四棵树凹陷中—下侏罗统煤系烃源岩,而新近系沙湾组油藏轻质原油来源于四棵树凹陷古近系湖相烃源岩。本文对准噶尔盆地西北缘南部地区油气藏成藏研究及区域油气勘探决策具有重要参考作用。     

油气初次运移理论新探

应用渗流力学的基本原理,研究油气初次运移的机制问题。研究认为,油气的初次运移是以连续相、而不是以溶液相和扩散相的形式进行的;油气初次运移的动力是浮力,因而初次运移的方向是向上的;油气初次运移所需的时间与源岩的渗透能力有关,与油气的粘度有关,还与源岩的厚度有关;油气藏的异常高压是一种暂时的压力状态,气藏的异常高压多于油藏,新生油气藏多于古油气藏;油气初次运移的通道就是源岩的粒间孔隙,源岩的非均质性和微裂缝对油气初次运移十分不利,因形成微油气藏而降低油气运移效率;源岩的厚度越大,越有利于油气聚集;“倒灌”现象是不存在的,缺少基本的动力驱动,基岩油气藏的形成是二次运移过程中侧向运移的结果。初次运移与二次运移具有相同的动力机制、运移相态和运移方向,因而两者是完全统一的。     

酒西坳陷石北次凹油气生成、运移成藏及勘探方向

酒泉盆地酒西凹陷石北次凹油气勘探历经70余年,仅在古近系发现了白杨河和单北两个小型油田。虽然许多探井在白垩系中也见到良好油气显示,但仅少数探井获得了低产油流,油气勘探始终未获得大突破。该凹陷究竟有没有勘探潜力以及油气勘探方向始终不清楚。通过对该凹陷大量烃源岩样品地球化学分析研究发现,该凹陷发育下白垩统中沟组、下沟组和赤金堡组三套潜在烃源岩。中沟组烃源岩有机质丰度较低、以Ⅲ型有机质为主,处于未成熟阶段,没有生油能力;下沟组和赤金堡组烃源岩有机质丰度高、以II有机质为主,属于优质烃源岩,其中下沟组烃源岩处于未成熟—低成熟阶段,仅具有生成少量低成熟原油的可能性,赤金堡组烃源岩处于低成熟—成熟阶段,具有生成低成熟和成熟石油的能力。石北次凹烃源岩主要生油期为新近纪末期至第四纪早期,目前生烃作用已基本停止。石北次凹已经发现了三种不同类型原油,第一类原油为低成熟原油,分布于浅层古近系,来源于石北次凹低成熟的赤金堡组上段烃源岩;第二类原油为中等成熟原油,分布于西部斜坡浅层古近系,来源于青南次凹下沟组中段烃源岩;第三类原油为成熟原油,分布于凹陷深层赤金堡组砂岩储层,来源于石北次凹成熟的赤金堡组中下段烃源岩。白杨河、单北和单东油田原油属于第二类原油,为长距离运移成藏,鸭儿峡至石北次凹西部斜坡地区为该类原油有利的勘探区域,古近系则为主要勘探目标层系。白南3井、白南6井赤金堡组原油属于第三类原油,为近距离运移自生自储型油藏,石北次凹中北部深层赤金堡组为该类原油最有利的勘探目标层系,包括常规油藏和非常规致密油藏。     

油气初次运移理论新探

应用渗流力学的基本原理,研究油气初次运移的机制问题。研究认为,油气的初次运移是以连续相、而不是以溶液相和扩散相的形式进行的;油气初次运移的动力是浮力,因而初次运移的方向是向上的;油气初次运移所需的时间与源岩的渗透能力有关,与油气的粘度有关,还与源岩的厚度有关;油气藏的异常高压是一种暂时的压力状态,气藏的异常高压多于油藏,新生油气藏多于古油气藏;油气初次运移的通道就是源岩的粒间孔隙,源岩的非均质性和微裂缝对油气初次运移十分不利,因形成微油气藏而降低油气运移效率;源岩的厚度越大,越有利于油气聚集;“倒灌”现象是不存在的,缺少基本的动力驱动,基岩油气藏的形成是二次运移过程中侧向运移的结果。初次运移与二次运移具有相同的动力机制、运移相态和运移方向,因而两者是完全统一的。     

一个典型的寒武系油藏:塔里木盆地塔中62井油藏成因分析

塔里木盆地志留系沥青砂岩广泛发育,主要原因是来源于寒武系的原油在进入志留系储层后区域性的抬升剥蚀使油藏遭到严重破坏,但到目前为止,究竟是寒武系烃源岩还是中上奥陶统烃源岩或是两者都对现今的志留系沥青砂岩中的有机质有贡献还不清楚.对塔中62井原油的化学组成和油源的分析表明,其甾萜类组成具有寒武系烃源岩的组成特征,反映该油藏原油主要来源于寒武系.另一方面,塔中62井砂岩透镜体被泥岩圈闭,油藏具有较好的保存条件,且后期中上奥陶统生成的烃类难以充注进入油藏.塔中62井志留系油藏破坏作用较弱、保存较好,是塔里木盆地在志留系发现的第一例来源于寒武系的油藏.     

Reservoir Geochemistry of the Kuche Petroleum System in the Tarim Basin, China

The geochemical characteristics of crude oils and reservoir core extracts from the Kuche petroleum system are described and studied systematically by means of various geochemical techniques and methods to acquire molecular information. The results suggest crude oils from the petroleum system can be divided into two groups: marine oils and non-marine oils. The former represents the dominant oils found in the area. Tar mats were firstly discovered and determined accurately in terrestrial oil and gas reservoirs, with Lower Tertiary sandstone reservoirs in the Yaha oilfield of the Tarim Basin. However, based on the ratio of 20S/(20S 20R)C29 sterane as a maturity parameter, lacustrine oils filled into the Tertiary reservoirs in the direction toward the western part of the petroleum system. In contrast, according to the fact that methylcyclohexane indices of eastern oils are greater than those of western oils, the location in which coalgenerated oils filled into the Tertiary reservoirs lies in the eastern part of the petroleum system.     

Geochemical Investigation of the Cretaceous Crude Oil Reservoirs and Source Rock Samples in One of the Abadan Plain Oilfields, SW Iran

Crude oil and source rock samples from one of the main oilfields of the Abadan Plain, Zagros, Iran were analyzed geochemically. Rock-Eval pyrolysis was conducted on Kazhdumi (Upper Cretaceous) and Gadvan (Lower Cretaceous) formations, which are the probable source rocks for the oil in the region. The results indicated that the Kazhdumi Formation can be classified as a fair-to-excellent source rock, while the Gadvan Formation can be identified as having poor-to-good source rock in the basin. Based on the cross-plots of HI versus OI and S2 versus TOC, types II and III kerogen were identified from studied source samples in the area. Determination of the main fraction percentages of the Sarvak and Fahliyan crude oils represented that the oils from the Sarvak reservoir are paraffinic-naphthenic and aromatic-intermediate, whilst that from the Fahliyan reservoir is paraffinic and paraffinic-naphthenic. Biomarker ratios of the saturated fractions of oil from both reservoirs indicate that the source rocks formed in reducing marine environments with carbonate-shale lithology. Furthermore, biomarker data helped to distinguish the degree of biodegradation in the studied oils. According to geochemical analysis, oil samples from the Fahliyan reservoir were generated at a higher thermal maturity than the Sarvak reservoir samples.     

准噶尔盆地三叠系生源油藏的发现及其意义

首次在准噶尔盆地发现了来源于三叠系烃源岩的典型原油，其地球化学特征与以往发现的石炭系、二叠系和侏罗系烃源岩生成原油均不同。该原油全油碳同位素δ^13C值为-3l‰左右，与石炭系和侏罗系原油差异很大；生物标志物中富含重排甾烷、Ts、C29Ts及C30重排藿烷，而伽马蜡烷和β-胡萝卜烷含量低，与三叠系烃源岩抽提物中生物标志物的分布十分相似，而与二叠系和侏罗系明显不同。二叠系、三叠系和侏罗系烃源岩的地球化学特征对比分析研究表明，三叠系是仅次于二叠系的良好烃源岩，具有较高的生烃潜力，是该盆地中又一套重要的烃源岩层系。油源对比表明该原油来源于三叠系烃源岩。三叠系生源原油的发现对该盆地油气勘探具有十分重要的意义。     

Critical conditions for tight oil charging and delineation of effective oil source rocks in Lucaogou Formation,Jimusar Sag,Junggar Basin,northwest China

Although tight oil has great resource potential, studies of oil charging mechanisms in tight reservoirs are relatively few. Researchers have found that a force balance exists during oil charging, but quantitative analyses of conditions critical for tight oil charging are sparse. This study developed a formula to identify effective source rocks using oil expulsion intensity as the discrimination parameter based on quantitative expression of hydrocarbon-generation overpressure and force-balance conditions. Using this formula, critical oil expulsion intensity under conditions at various burial depths can be obtained. This method was applied in the tight reservoirs of the Jimusar Sag, Junggar Basin, China. The calculated critical oil expulsion intensity range was between 122.61 × 10⁴ t/km² and 620.01 × 10⁴ t/km². The distribution range of effective oil source rocks and total expelled oil can be determined on the basis of critical oil expulsion intensity at different burial depths. This method provides a new approach to predict favourable tight oil-bearing regions.     

Geochemistry and origin of deep-seated cracked gas on the northern slope of the Dongying Sag, Shandong Province

Deep-seated cracked gas exploration was achieved great breakthrough in Es4L of the Minfeng area on the northern slope of the Dongying Sag. Carbon isotopic and molecular compositions studies revealed the characteristics of wet gas and a normal trend of carbon isotopic composition. Empirical cutoff points of δ13C2 and δ13C3 and light hydrocarbon compositions distinguished the cracking gas as sapropelic gas. Variations in i/nC5, i/nC4 and δ13C2 fur-ther confirmed that the gas was cracked from residual kerogen. Source characteristics indicated that the gas was de-rived from mature-highly mature source rocks of Es4 with kerogen type II being dominant mixed with some oil-cracking gas. Burial history modeling indicated that there were two hydrocarbon charging periods in Es4L reser-voirs. The first period refers to the Guantao-Minghuazhen stage dominated by oil charging, while the second period refers to the Minghuazhen stage and has been dominated by cracked gas charging till now.     

Geochemical characteristics of saturate hydrocarbons in crude oils and source rocks of the Qaidam, Tarim, Tupran basins, NW China

Based on the systematic analyses of fifteen typical crude oils and ten typical potential source rocks col-lected from the Qaidam,Tarim and Turpan basins,Northwest China,the geochemical characteristics of the oils and source rocks were investigated and oil-source rock correlations undertaken.The oils and source rocks deposited in saline lacustrine environment from the western Qaidam Basin were characterized by n-alkanes with even car-bon-number preference in the C20-C28 range,low pristane/phytane(Pr/Ph) ratios(less than 0.5),and high abundances of C27 steranes,gammacerane and C35 hopanes.The oils and source rocks deposited in marine environment from the Tarim Basin were characterized by n-alkanes with even carbon-number preference in the C14-C18 range,relatively low Pr/Ph ratios(near to 1),high abundance of C28 steranes,and relatively high gammacerane.In contrast,the oils and source rocks deposited in terrigenous bog environment from the Turpan Basin were characterized by relatively high Pr/Ph ratios(oil samples greater than 6) high abundance of C29 steranes,and relatively low gammacerane and C31-35 hopanes.The higher amounts of C37 and C38 n-alkanes of source rocks from the western Qaidam Basin and the Tarim Basin suggest an origin of these alkanes from functionalized C37 and C38 n-alkadienes and alkenones in prymnesiophytes living in lacustrine and marine environments.Oil-source rock correlations suggest oils in the west-ern Qaidam Basin were derived from the Oligocene Lower Ganchaigou Formation(E3),oils in the Tabei and Tazhong uplifts from the Tarim Basin have a genetic relationship with the Middle-Upper Ordovician source beds.Oils in the Turpan Basin generally fall into two genetic types.Most oils in the Taibei depression from the Turpan Basin were derived from the Lower-Middle Jurassic coal measures,but the fewer oils in this region are a mixed source derived from the Lower-Middle Jurassic coal measure and the Upper Permian source rocks.     

准噶尔盆地烃源岩与原油地球化学特征

准噶尔盆地是中国西部典型的多旋回叠合盆地,发育石炭系、二叠系、三叠系、侏罗系、白垩系和古近系6套烃源岩,广泛分布于盆地不同地区。石炭系海陆交互相烃源岩分布于盆地大部分地区,泥岩有机质丰度中等,以Ⅱ型有机质为主,碳质泥岩和煤有机质丰度高、类型差。二叠系湖相烃源岩分布广、厚度大,有机质丰度高、类型好,干酪根碳同位素组成轻,是盆地中最主要的烃源岩。三叠系湖相烃源岩在盆地东部有机质丰度较高、以Ⅱ型有机质为主。侏罗系为煤系烃源岩,有机质丰度高,但以Ⅱ_2型和Ⅲ型有机质为主,干酪根碳同位素组成重。白垩系和古近系湖相烃源岩主要分布于盆地南部,有机质丰度中等,但以Ⅰ、Ⅱ型有机质为主。石炭系烃源岩目前主要处于高—过成熟阶段,二叠系、三叠系烃源岩主要处于成熟—高成熟阶段,侏罗系烃源岩在大部分地区未成熟—低成熟,只在南部与东部坳陷达到成熟—高成熟,白垩系和古近系烃源岩目前也只在南部坳陷处于低成熟—成熟演化阶段。准噶尔盆地目前发现了6大类典型原油,其地球化学特征存在很大差异。第一类原油碳同位素组成特别重(δ~(13)C-26‰);第二类原油碳同位素组成轻(δ~(13)C-29‰)、含有丰富的胡萝卜烷、类异戊二烯烷烃、三环萜烷和伽马蜡烷,甾烷以C_(28)、C_(29)为主,基本没有重排甾烷;第三类原油碳同位素轻(δ~(13)C-29‰)、重排甾烷、Ts、C_(29)Ts及C_(30)重排藿烷异常丰富;第四类原油碳同位素组成重(δ~(13)C-28‰~-26‰),Pr/Ph大于2.5,三环萜烷含量低且以C_(19)、C_(20)为主,藿烷系列丰富,伽马蜡烷极低,甾烷以C_(29)规则甾烷及重排甾烷为主;第五类原油碳同位素组成轻(δ~(13)C-29‰)、Pr/Ph1.0、伽马蜡烷丰富且有两个异构体、Ts、C_(29)Ts、C_(30)重排藿烷、C_(27)~C_(29)异胆甾烷及C_(30)甲基甾烷十分丰富;第六类原油主要为中低成熟油,碳同位素组成重(δ~(13)C-28‰~-26‰),C_(27)、C_(28)、C_(29)甾烷呈Ⅴ型分布,甲藻甾烷异常丰富。第二类原油广泛分布于盆地不同区域,其他类型原油均只分布于盆地局部地区。西北缘地区以第二类原油为主,可分为3个亚类;腹部地区以第二类原油为主,可分为4个亚类,还有少量第四类原油;东部地区有前4类典型原油,此外还有混合原油;南缘地区目前发现有第二、第四、第五及第六类4种典型原油,也有少量混合原油。     

乌兰花凹陷原油特征及成因

乌兰花凹陷是二连盆地南部新发现的富油凹陷,对乌兰花凹陷原油物理性质和地球化学性质进行了系统的分析以揭示其特征及来源。原油物理性质显示,乌兰花凹陷原油比重（API gravity）介于20.2°~40.0°之间,主体为正常原油。原油生物标志化合物参数表明,不同构造带之间原油特征存在差异,可以划分为两类原油。一类以土牧尔构造带原油为主,具有低姥值比（Pr/Ph）和C₂₁/C₂₃三环萜烷,相对较高的伽马蜡烷/C₃₁藿烷和规则甾烷/C₃₀藿烷的特征,原油主要为烃源岩在成熟阶段早期的产物,主要以藻类来源为主。另一类原油包括赛乌苏和红井构造带原油,具有高姥值比（Pr/Ph）和C₂₁/C₂₃三环萜烷,相对较低的伽马蜡烷/C₃₁藿烷和规则甾烷/C₃₀藿烷,主要为陆源有机质和藻类有机质混合来源,原油具有更高的成熟度。原油碳同位素和正构烷烃单体烃碳同位素表明这两类原油应是一套烃源岩在不同成熟阶段的产物,原油主要来源于南洼槽阿尔善组烃源岩。阿尔善组烃源岩的非均质性和成熟度导致了两类原油的差异。      

惠州凹陷文昌组烃源岩及相关原油中的2-甲基藿烷系列

首次报道了在惠州凹陷文昌组优质烃源岩及相关原油中普遍存在丰富的2-甲基藿烷系列生物标志物,而在恩平组烃源岩中则几乎缺乏这类生物标志物,其分布具有明显的专一性。这类特殊生物标志物在该地区沉积地层中分布特征的专一性是由不同时期沉积水体的水化学条件决定的。生物化学的研究结果表明,蓝细菌中富含2-甲基藿烷多醇,它们是2-甲基藿烷系列的前身物,因此蓝细菌是这类生物标志物的主要生物来源。依据现有的文献资料,发现较丰富的2-甲基藿烷系列大多出现在碳酸盐岩沉积中,显然这是一种偏碱性的水介质条件,可能暗示着这样的环境有利于蓝细菌的大量发育,这也可能是控制惠州凹陷文昌组和恩平组烃源岩中2-甲基藿烷系列分布规律的主要因素。2-甲基藿烷系列在不同层位烃源岩中分布的专一性可以作为确定原油的成因类型和追溯原油的来源可靠的指标。     

Compositional characteristics and geochemical significance of light hydrocarbons for crude oils in Tarim Basin, China

Light hydrocarbons, especially C7 isoalkanes, cyclopentanes, cyclohexanes and n-heptane in 540 oils from the Tarim Basin were studied systematically. The results suggested the K1 values [ （2-MH＋ 2,3-DMP）/（3-MH ＋ 2,4-DMP） ] of crude oils vary from a lowest value of 0.78, to a highest value of 1.54, but the K1 values of the majority of oil samples （80%） range from 0.90 to 1.20. However, the absolute contents of （ 2-methylhexane ＋ 2,3-dimethylpentane） and （ 3-methylhexane ＋ 2,4-dimethylpentane） in the total light hydrocarbons （ C4-C7 ） show a similar variation trend. The variation of K1 values of crude oils can suggest a typical sedimentary environment for source rocks. Therefore, according to the compositional characteristics of C7 light hydrocarbons in light of the steady-state catalytic hypothesis, nonmarine oils from the Yingmaili area and marine oils from the Tazhong uplift in the Tarim Basin were genetically classified.     

石柱复向斜及周缘下志留统砂岩碎屑组分特征及其构造意义

通过系统研究石柱复向斜露头和钻井剖面的砂岩薄片,统计分析了下志留统龙马溪组、小河坝组、韩家店组砂岩碎屑组分特征,在此基础上,进行了砂岩多碎屑的Dickinson图解分析,对物源区类型和板块构造背景进行了分析。研究结果表明,研究区下志留统主要物源区的板块构造位置为被动大陆边缘,总体上看,研究区下志留砂岩的成熟度和稳定度很高,反应本区距物源区具有相当远的距离,陆源碎屑经过较为充分的搬运;龙马溪组砂岩主要来自稳定克拉通和再旋回造山带,小河坝组砂岩主要来自稳定克拉通,韩家店组砂岩主要来自再旋回造山带,反映华南板块和扬子板块的拼接除奥陶纪末期的初次碰撞外,早志留世均呈现出幕式、蠕动式的非刚性拼接特点。     

福建平和矾山地区围岩蚀变特征与找矿潜力分析

平和矾山地区围岩蚀变类型为次生石英岩化,可细分为石英-黄铁矿-明矾石化、硅化和绢云母-叶蜡石化等三个相带,具北西向带状对称式水平分带和略显垂直分带现象.蚀变以高硫型明矾石次生石英岩化为主,相当于紫金山铜金矿床蚀变分带的外带,即石英-明矾石化带.深部可能贮存有隐伏的铜多金属矿体,有进一步找矿的前景.     

胶东金青顶金矿床围岩蚀变特征与金矿化

金青顶金矿围岩蚀变发育,从近矿到远矿依次发育黄铁绢英岩化、绢英岩化和钾长石化,并呈近似对称的带状分布.由地表至深部,钾长石化蚀变强度有增大的趋势,局部出现膨大收缩的豆英状构造特征;绢英岩化浅部较发育,深部反复尖灭重现;黄铁绢英岩化带宽度很窄,仅浅部独立成带产出.各类蚀变过程中与Au成矿相关的Ag、As、Hg等元素含量增加,蚀变围岩中成矿元素以带入为主,推测围岩的主要作用是冷却成矿热液,并改变其化学性质,使成矿物质在有利的容矿空间沉淀富集,而非提供成矿物质的母岩.     

山东省临邑县临盘镇地裂冒喷水油灾害初步分析

1998年7月临邑县临盘镇西十二里村发生地裂冒喷水油灾害：对此次灾害研究认为，灾害发生前地应力已有明显改变，这种改变应是自然因素造成的，油田开发难以直接引发断层的活动。因此，地裂冒喷水、油灾害是因活动性断昙——临邑断层在局部薄弱部位活动而引起的，断层活动使地下流体顺断层涌出地表，是自然地质灾害。灾害的诱发因素是多方面的，其中地面不均衡沉降耦合使得地下应力布不均习，导致在断层的薄弱部位产生应力集中，并引发灾害发生。灾害发生已使得地下不均衡应力得以释放，近期内再次发生灾害的可能性不大。