襄城凹陷未熟-低熟油的形成条件

襄城凹陷下第三系油气显示较为广泛,原油性质呈高密度、高黏度、高含硫、高含蜡的特点,为典型的未熟-低熟油。根据襄城凹陷所处的区域构造背景及烃源岩和原油的有机地球化学特征,采用有机显微组分分析、生物标志物检测、有机岩石学研究等方法,对源岩的沉积环境、烃源岩特征以及生烃母质来源进行了深入分析,探讨了未熟-低熟油油藏形成的主要地质条件。研究结果表明,核桃园组多为半咸水-咸水湖相和盐湖相沉积,属于还原-强还原环境; 形成未熟-低熟油的主要成烃母质是藻类,陆源有机质中的木栓质体、角质体和各种细菌;应以核二段为主要目的层,以寻找短距离运移、聚集及自生自储油气藏为主。     

碳同位素类型曲线在辽河盆地油源对比中的应用

方法 利用原油及其组分中碳同位素值所构成的同位素类型曲线,对辽河盆地东、西部凹陷两个不同地区的原油进行油－油和油－源对比。目的 区分来自不同母岩的原油,并根据碳同位素类型曲线判断油源。结果 西部凹陷高升雷家地区未熟低熟油与东部凹陷南部地区原油类型曲线分布特征差别明显。高升雷家地区未熟低熟油来自沙四段源岩,东部凹陷南部地区原油主要来自沙三段部分来自沙一段,这与用其它地球化学指标得出的结论相吻合。结论     

泌阳凹陷北部斜坡石油成藏组合特征

泌阳凹陷北部斜坡发育有Eh3^上亚段未熟-低熟原油、Eh3^上产亚段成熟原油和Eh3^下亚段低熟原油，分别来自于凹陷中部Eh3^上亚段成熟烃源岩，古城东南部Eh3^上亚段未熟-低成熟烃源岩和杨楼油田Eh3^下亚段未熟-低熟烃源岩。在成藏期次分析基础上，根据北部斜坡储集层分布、油源类型、油气运聚与圈闭形成的配套情况，可划分出3个成藏组合，即王集-新庄Eh3^上亚段成熟油成藏组合、杨楼Eh3^下亚段未熟-低熟油成藏组合、古城断鼻复合成藏组合。     

松辽盆地北部未熟-低熟油成藏特征

未熟－低熟油系指沉积成岩作用早期阶段,由尚未达到生油门限的烃源岩生成的原油,是有别于干酪根晚期成油的一类非常规石油资源,以松辽盆地北部为研究重点,从松辽盆地未熟－低熟烃源岩的分布特征入手,对未熟－低熟油藏进行研究,分析未熟－低熟油成藏条件、分布规律、总结出未熟－低熟油运聚成藏特征,主要有上生、下储垂向运移成藏;下生、上储垂向运移成藏,短距离侧向运移成藏;多源混合运移成藏,从而为松辽盆地北部扩大油气勘探领域提供理论依据。     

蓬莱19-3油田未熟—低熟油特征及形成条件

蓬莱19-3油田是中国海域发现的最大油田,该油田所产原油部分为未熟—低熟油。利用大量的原油和烃源岩等实验资料,对蓬莱19-3油田未熟—低熟油的原油物性、族组分和生物标志化合物等特征进行了系统分析,并从烃源岩沉积环境、烃源岩特征和成烃母质等方面对未熟—低熟油的形成条件进行了探讨。研究结果表明:蓬莱19-3油田未熟—低熟油密度高、黏度高、含硫量中等、含蜡量低,具有饱和烃含量低、饱/芳比低、非烃含量偏高、非/沥比高、Pr/Ph低、重排甾烷丰度低和TsTm等特征;半咸水—咸水沉积环境、烃源岩有机质类型好且丰度高、有机质演化程度低是烃源岩生成未熟—低熟油的有利地质条件。     

苏北盆地混源油气地球化学与成藏特征

金湖凹陷原油族组成具典型未熟-低熟油的特征,普遍检出热稳定性低的化合物,碳优势指数、奇偶优势与藿烷成熟度参数体现成熟特征,但甾烷成熟度参数存在明显变化,原油来自4个不同成熟度的运聚场,定量计算了不同地区的未熟油混合比例。盐城凹陷凝析油具与湖相原油和海相原油相似的混源特征,轻质组分反映一种高成熟演化特征,中等组分体现出未熟-低熟的特征,重组分反映达到或超过了主要生油演化阶段,下生上储成藏模式使高成熟天然气对成熟原油进行了气洗作用,造成了凝析油的“特殊”特征。     

襄城凹陷未熟—低熟油形成条件探讨

从襄城凹陷所处的区域构造背景、沉积环境变迁等主要地质问题出发,结合烃及原油的有机地球化学特征,采用有机显微组分分析、生物标志物检测、有机岩石学研究等方法,对烃有机质丰度、类型,特别是生烃母质来源进行了深入的分析,阐明了襄城凹陷核桃园组未熟油的判别标志和成因类型,探讨了未熟—低熟油藏形成的主要地质条件,指出研究区勘探应以核二段为主要目的层,以寻找短距离运移聚集、自生自储的断鼻、岩性、裂隙油气藏为主。     

蓬莱19-3/25-6油田未熟—低熟油特征与成因

利用大量最新的原油和烃源岩等实验资料,系统分析了蓬莱19-3/25-6油田未熟—低熟油的特征、来源及其形成条件,并探讨了未熟—低熟油的主要成因机理。研究结果表明,蓬莱19-3/25-6油田未熟—低熟油埋藏较浅,具有密度高、黏度高、饱和烃含量低、饱/芳比低、非烃含量高、非沥比高、Pr/Ph低、重排甾烷丰度低和TsTm等特征。油源对比结果表明,这些未熟—低熟油来自本井区及邻近沙一、二段和沙三段未熟—低熟烃源岩,强还原的半咸水—咸水沉积环境、烃源岩有机质丰度高且类型好、主要生烃母质为藻类和有机质中的各种细菌是这2套烃源岩形成未熟—低熟油的有利地质条件,藻类有机质早期生烃、细菌改造有机质早期生烃和碳酸盐岩低温热催化早期生烃是主要成因机理,这些成因机理共同作用生成了大量的未熟—低熟油资源,对蓬莱19-3/25-6大型油田的形成具有不可忽视的贡献。     

蠡县斜坡北段古近系沙河街组一段油气来源分析

蠡县斜坡是位于冀中坳陷中部饶阳凹陷西部的次级构造,是一个在前古近纪古隆起上发育起来的西抬东倾、北东走向的继承性宽缓沉积斜坡。理清斜坡北段古近系沙河街组油气来源,是油气成藏研究的基础,对该区的勘探开发具有重要的意义。通过对斜坡北段原油及烃源岩地球化学特征分析,选取正构烷烃、甾萜烷等地化指标进行油源综合对比,结果表明,蠡县斜坡北段原油植烷优势明显,伽马蜡烷含量相对较高,形成于咸水还原沉积环境,未熟—低熟的特征,主要来源于沙一下亚段烃源岩层。     

渤中坳陷QHD30-1构造油气充注史

应用油气组成、生物标志物与碳同位素分析资料对渤中坳陷QHD30-1构造油气地球化学研究表明,该构造馆陶组原油为正常成熟度原油;沙一段凝析油为早期低熟油被后期高成熟天然气气侵之后形成的;孔店组原油为低熟油。油源对比表明,该构造低熟油与正常成熟度原油主要来自构造周围沙河街组烃源岩,而沙一段高成熟天然气来自秦南凹陷高成熟烃源岩。综合该区构造、沉积与地球化学特征,对该区油气多期充注过程进行了分析。     

渤海湾盆地东营凹陷孔店组烃源岩特征研究

沙三下和沙四上是东营凹陷的2套优质烃源岩。目前认为东营凹陷南斜坡原油主要属于“沙四型”,而对于东营凹陷孔店组的生烃潜力一直存在着争论。油源对比结果表明,孔店组烃源岩以较高的伽马蜡烷区别于沙三型烃源岩,又以较高的三升藿烷和C₂₉甾烷S构型区别于沙四型烃源岩;南斜坡孔店组及其以下的深层原油与孔店组烃源岩具有亲缘关系。虽然目前发现的孔店组烃源岩有机质含量较低、类型差、成熟度较高,综合评价较差,但是生物标志化合物显示,向沉积中心其有机质有优化的趋势。因此推测在沉积中心发育更优质的孔店组烃源岩,其生烃潜力不容忽视。      

济阳坳陷车西洼陷油-源对比及运移规律探讨

通过对车西洼陷下第三系烃源岩特征、原油地化特征及油源对比、油气运移规律的综合研究认为,现今埋深2800~3000m以下的Es3(下—中)烃源岩是车西洼陷主力烃源岩,埋深2200m以下的Es3(上)及Es1烃源岩具有一定的低熟资源潜力;目前已发现的原油绝大多数源于Es3(下)优质烃源岩,而源于Es3(中),Es3(上)及Es1烃源岩的原油仅有零星发现;Es3(下)烃源岩早期生成油气以顺油源断层垂向运移至Es2储层成藏为主,后期由于垂向运移通道封闭,则以侧向进入Es4(上)储层或古潜山储层中成藏为主,Es3(下)烃源岩下伏Es4(上)储层或古潜山储层圈闭应该是今后勘探的重点。      

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位于准噶尔盆地腹部的石南油田，四面分别与玛湖凹陷、盆1井西凹陷和石南凹陷相邻，其石油地质储量超过1×108t。石南凹陷二叠系烃源岩有机质成熟度低、类型差、生烃量小；盆1井西凹陷二叠系烃源岩有机质从成熟—过成熟均有分布、有机质类型好、生烃量巨大，玛湖凹陷烃源岩与盆1井西凹陷烃源岩石油地质特征相似，但因其中生界构造特征而被排除。文章运用有机地球化学方法，分析并类比了烃源岩和原油中C₂₀、C₂₁、C₂₃三环二萜烷和甾烷等生物标志化合物特征，确定：①石南油田油气主要来源于盆1井西凹陷二叠系风城组和下乌尔禾组烃源岩；②油气运移的通道主要是断层和不整合面；③油气至少有两期成藏。     

未成熟碳酸盐生油岩地球化学特征初探

江苏句容盆地继下青龙组(T₁x)碳酸盐岩产层中发现自生自储的低—中等成熟度原油之后,又在上覆上青龙组(T₁s)见到未成熟的碳酸盐生油岩。这种在地质时代相对较老的早三叠世中见到未成熟碳酸盐生油岩的情况,国内尚属首次发现,值得引起重视。本文主要应用烃类组成、岩石热解色谱、烷烃气相色谱、干酪根红外吸收光谱和镜质体反射率等分析成果,对未成熟碳酸盐生油岩的地球化学特征及其地质成因进行探讨。      

APPLICATION OF BIOMARKERS AND STABLE CARBON ISOTOPES TO ASSESS THE DEPOSITIONAL ENVIRONMENT OF SOURCE ROCKS AND THE MATURATION OF CRUDE OILS,EAST ZEIT FIELD,SOUTHERN GULF OF SUEZ,EGYPT

Four crude oil samples were collected from the producing wells EZ A-11, EZ A-1, EZ A-14 and EZ A-7 of East Zeit Field, offshore southern Gulf of Suez, Egypt. These crude oil samples represent the producing Kareem, Rudeis, Nukhul and Nubia reservoirs respectively. The crude oils were subjected to a variety of organic geochemical analyses including Gas Chromatography (GC), Gas Chromatography-Mass Spectrometry (GC-MS). In addition to stable carbon isotopes were done for the saturate and aromatic fractions and trace elements analysis. The organic geochemical results suggest the presence of two different types of oils that were originated from two different source environments. The Lower Miocene Kareem, Rudeis and Nukhul oils have a V/Ni ratios of 2, Ts/Tm ratio less than 1, Oleanane index of more than 20% and a gammacerane index of around 10%. Such results suggest that the Miocene crude oils were generated from an angiosperm-rich, Tertiary source rocks with high terrestrial input. The Nubian crude oil has a V/Ni ratio equal 3.2, Ts/Tm ratio less than 1, Oleanane index less than 20% and high gammacerane index of more than 30% suggesting a marine saline-source depositional environment of Late Cretceous or younger rich in type-II kerogen with minor terrestrial influence. The maturation parameters of the Miocene and Nubian crude oils obtained from aromatic and fraction imply marginally mature to mature oils. The Nubian crude oil however, was generated at a relatively higher maturation level than that of the Miocene oils. Also, the maturation level of the Miocene oils is in accordance with their relative stratigraphic position with the Nukhul reservoired oil being the most mature.     

APPLICATION OF BIOMARKERS AND STABLE CARBON ISOTOPES TO ASSESS THE DEPOSITIONAL ENVIRONMENT OF SOURCE ROCKS AND THE MATURATION OF CRUDE OILS, EAST ZEIT FIELD, SOUTHERN GULF OF SUEZ, EGYPT

Four crude oil samples were collected from the producing wells EZ A-11, EZ A-1, EZ A-14 and EZ A-7 of East Zeit Field, offshore southern Gulf of Suez, Egypt. These crude oil samples represent the producing Kareem, Rudeis, Nukhul and Nubia reservoirs respectively. The crude oils were subjected to a variety of organic geochemical analyses including Gas Chromatography (GC), Gas Chromatography-Mass Spectrometry (GC-MS). In addition to stable carbon isotopes were done for the saturate and aromatic fractions and trace elements analysis. The organic geochemical results suggest the presence of two different types of oils that were originated from two different source environments. The Lower Miocene Kareem, Rudeis and Nukhul oils have a V/Ni ratios of 2, Ts/Tm ratio less than 1, Oleanane index of more than 20% and a gammacerane index of around 10%. Such results suggest that the Miocene crude oils were generated from an angiosperm-rich, Tertiary source rocks with high terrestrial input. The Nubian crude oil has a V/Ni ratio equal 3.2, Ts/Tm ratio less than 1, Oleanane index less than 20% and high gammacerane index of more than 30% suggesting a marine saline-source depositional environment of Late Cretceous or younger rich in type-II kerogen with minor terrestrial influence. The maturation parameters of the Miocene and Nubian crude oils obtained from aromatic and fraction imply marginally mature to mature oils. The Nubian crude oil however, was generated at a relatively higher maturation level than that of the Miocene oils. Also, the maturation level of the Miocene oils is in accordance with their relative stratigraphic position with the Nukhul reservoired oil being the most mature.     

柴达木盆地第三系原油的熟化序列及其在石油资源预测中的重要意义

对柴达木盆地第三系54个生油岩和原油样品,进行系统的地球化学检测,并以生物标记物中C₂₉甾烷的异构化程度作为成熟度标尺,发现该盆地的原油有一个从未成熟、低成熟、成熟直至高成熟的完整演化系列。相应于生油岩中有机质不同成烃演化阶段的产物。现有资料表明,在我国陆相第三系沉积盆地中,未成熟石油和原油熟化系列的普遍存在,是含油上一个重要的地球化学特征。它突破了干酪根成烃学说的局限性,并且在油气的勘探上有着重要的实际意义,为以成熟度分级的油气资源预测提供了科学的依据。研究表明,柴达木盆地目前所发现的石油,大部分是低成熟的,其它成烃演化阶段的石油,特别是深层成熟石油的勘探,还大有可为。     

THE GENERATION OF IMMATURE OILS IN THE LACUSTRINE JIYANG MEGA-DEPRESSION, BOHAI BAY BASIN, CHINA

The lacustrine Jiyang mega-depression (Bohai Bay Basin, eastern China) produces important volumes of immature oils. These oils were generated at shallow burial depths by source rocks which have not entered the conventional oil window. Oil-source correlation studies have determined that the oils were mainly generated by source rock intervals in the Es4 and Es1 Members of the Paleogene Shahejie Formation, which were deposited in saline- to brackish-water and brackish-water lacustrine conditions, respectively. Minor quantities of oil came from Es3 Member source rocks deposited in freshwater conditions.
Samples of the Es4, Es3 and Es1 source rocks underwent artificial maturation at low temperatures (100–400°C). For the Es4 sample, the hydrocarbon generation characteristics of soluble organic matter and kerogen were investigated. The results of the experiments show that soluble organic matter made a greater contribution than kerogen to the immature oil (76% versus 24%). A comparison of the results of the thermal simulation experiments with the naturally-occurring maturation profile shows that various factors influenced the generation of the immature oils. Firstly, the Es4 and Es1 Members include intervals enriched in algal material. Secondly, most of the immature oil is derived from soluble organic matter. Finally, the saline depositional environment was favorable for the preservation of organic matter.     

南襄盆地泌阳凹陷核二段未熟-低熟油勘探潜力分析

对泌阳凹陷核二段沉积环境、沉积特征和烃源岩有机质丰度、类型、演化程度等研究表明,位处深凹的安棚地区发育的泥质岩为未熟—低熟烃源岩,属较好—好的生油岩,提供了丰富的油源。油源对比证实,白云岩区外围的砂泥岩区同样存在有未熟—低熟油,且与白云岩区的未熟—低熟油有相似的地球化学特征,它们均来自核二段泥质烃源岩。安棚白云岩区南北两侧附近的砂泥岩区具有勘探未熟—低熟油藏的潜力。     

焉耆盆地原油物理化学特征及油源对比研究

在焉耆盆地侏罗系三工河组和八道湾组均发现原油,目前关于侏罗系产层原油的油源问题存在不同的认识。对研究区原油的物理、化学性质进行系统的研究,认为侏罗系三工河组和八道湾组原油不仅在物理性质上有一定的差别,而且在地球化学组成及生物标记化合物上也有一定的差异,应具有不同的来源。侏罗系三工河组原油属于典型腐殖型干酪根成因,而侏罗系八道湾组原油除了具有腐殖型干酪根成因的某些特征外,还具有湖相泥岩生烃的特点。通过原油与各类源岩生物标志物进一步对比分析发现,侏罗系三工河组原油与西山窑、三工河组烃源岩及石炭系、三叠系烃源岩地球化学特征均存在明显差异,与侏罗系八道湾组烃源岩对比性较好。侏罗系八道湾组原油与八道湾组、三叠系源岩有一定相似性,因此认为八道湾组源岩为其主要源岩,三叠系源岩也有一定的贡献。目前勘探生产主要以八道湾组烃源岩为目标,下一步应加强对三叠系烃源岩贡献区带的勘探部署。