塔中4油田石炭系储层不同赋存态烃类分子和碳同位素对比研究

塔中421井和塔中402井石炭系油层2个原油样和8个油砂样连续抽提组分甾烷、萜烷分布特征和正构烷烃单体碳同位素组成具有明显的差异,具有不同的来源。塔中421井上石炭统3个油砂样自由态组分、束缚态组分和油气包裹体具有伽马蜡烷和C28甾烷相对含量高、正构烷烃单体碳同位素组成重的特征,划分为Ⅰ类原油,对比认为主要来源于寒武系-下奥陶统烃源岩。塔中421井和塔中402井上石炭统的2个油样具有伽马蜡烷和C28甾烷相对含量低、并且正构烷烃单体碳同位素组成轻的特征,划分为Ⅱ类原油,其来源尚不明确。塔中402井石炭系上、中和下统的5个油砂样各类组分具有介于Ⅰ、Ⅱ类原油之间的特征,为Ⅰ和Ⅱ类原油的混合物。5个油砂样从自由态组分、束缚态组分至油气包裹体Ⅰ类原油含量依次增高,Ⅱ类原油含量依次降低。2口井8个油砂样从自由态组分、束缚态组分至油气包裹体C23三环萜烷／（C23三环萜烷＋C30藿烷）和C21／（C21＋∑C29）甾烷比值都依次降低,反映了油气充注过程中,原油成熟度不断升高。塔中4井区储层油砂不同吸附态烃类分子与碳同位素的研究结果反映塔中4油田具有多种油气来源,经历长期油气充注过程,寒武系-下奥陶统烃源岩在地史上对该区具有成烃贡献。     

准噶尔盆地玛湖凹陷西斜坡百口泉组含油储集岩分子与碳同位素地球化学特征及其意义

在准噶尔盆地玛湖凹陷斜坡区下三叠统百口泉组地层中发现大面积连片岩性油气藏。对西斜坡百口泉组一段和二段8个含油储集岩样分别提取自由态组分、束缚态组分和油气包裹体组分,并进行GC、GC-MS和GC-IRMS分析。结果表明,3类油气组分三环萜烷主峰含量远高于C_(30)藿烷,反映充注到百口泉组(T1b)储层的原油均具有很高的成熟度,相当于Ro1.20%。生物标志物指标β-胡萝卜烷/(β-胡萝卜烷+nC20)、伽马蜡烷/(C_(30)藿烷+伽马蜡烷)、三环萜烷/(三环萜烷+藿烷)、Ts/(Tm+Ts)、C_(29)Ts/(C_(29)藿烷+C_(29)Ts)、C_(30)重排藿烷/(C_(30)重排藿烷+C_(30)藿烷)和甾烷C_(21)/(C_(21)+∑C_(29))比值均显示从自由态组分、束缚态组分至油气包裹体组分成熟度依次降低的特征,表明油气组分在油藏充注过程中不断升高。与此相反,Pr/nC_(17)和Ph/nC_(18)比值以及正构烷烃单体碳同位素组成显示从自由态组分、束缚态组分至油气包裹体组分成熟度依次升高的特征,表明油气组分从成藏早期至晚期成熟度降低。由于充注的原油为不同成熟度油气组分混合产物,生物标志物在原油中属于微量及痕量组分,而Pr、Ph和正构烷烃属于常量组分,Pr/nC_(17)和Ph/nC_(18)比值以及正构烷烃单体δ~(13)C值更能代表主体原油的成熟度。因此,对于玛湖凹陷西斜坡油气藏,主体原油成熟度从成藏早期至晚期是降低的。根据8个油砂样3类油气组分的成熟度可以推断油气充注期介于晚侏罗世-白垩纪之间。盖层密封性是控制这类油气藏成藏的重要因素。在晚侏罗世之前,下伏二叠系盖层一直阻止了油气沿断层运移。至晚侏罗世-白垩纪,下伏盖层的密封性遭受破坏,油气才从下伏二叠系沿断层运聚至百口泉组一段和二段储层(T_1b~(1–2))。由于上覆百三段(T_1b~3)和克拉玛依组(T_2k)盖层自始至终保持密封状态,百口泉组一段和二段储层(T_1b~(1–2))成为玛湖凹陷油气的最终归宿。     

普光气田及邻区碳酸盐储层沥青的分子地球化学研究

从普光气田及邻近地区二叠系和下三叠统15个含沥青碳酸盐储集岩样品分步提取了自由态油气组分和油气包裹体组分,并且应用限定体系(金管)热解实验获取了固体沥青热解组分.各组分进一步做色谱和色谱-质谱分析获取了生物标志物组成.分析结果表明,从油气包裹体组分、自由态油气组分至固体沥青热解组分,伽马蜡烷/C31升藿烷比值依次增高.同时油气包裹体组分 C23三环萜烷/(C23三环萜烷+C30藿烷)、C21/(C21+ΣC29)甾烷、C27重排甾烷/(C27重排甾烷+C27规则甾烷)、20S/(20R+20S) C29甾烷和αββ/(ααα+αββ) C29甾烷等成熟度指标与自由态组分相近,而明显高于固体沥青热解组分.根据分子指标,可以推断古油藏的原油来源于不同的烃源岩,早期充注的原油来源于下志留统烃源岩,具有较低的伽马蜡烷含量和较高的成熟度;晚期充注的原油来源于上二叠统烃源岩,具有较高的伽马蜡烷含量和较低的成熟度.固体沥青主要为晚期充注、来源于上二叠统烃源岩的原油裂解生气的产物     

MCI技术及其在塔中47油藏油源对比中的应用

流体包裹体成分分析技术(MCI)是应用分子有机地球化学参数研究烃类包裹体成分的一种方法。它与常规技术相比具有三个显著优点:可以分析包裹体内烃类组成,达到分子级水平;使用化学试剂氧化处理包裹体表面污染物,避免高温操作影响流体包裹体烃类组成;空白实验贯穿全过程以确保包裹体的清洁性。该技术能够成功解决源岩、成熟度、油气充注期次及油气二次蚀变等问题。选取塔中47井石炭系和志留系的两块样品进行了MCI分析,取得正构烷烃、萜烷、甾烷等分布参数。结果显示,塔中47油藏中石炭系与志留系原油属同源;与油砂抽提物相比,包裹体烃类的成熟度较低;志留系油砂与包裹体烃类有不同的母源;志留系中至少存在两期油气充注,其晚期充注的油气有轻微水洗或生物降解作用。     

盐城凹陷凝析油地球化学特征

运用碳同位素、气相色谱、色谱—质谱、流体包裹体技术，研究了盐城凹陷凝析油地球化学特征，并与永安凹陷永7井凝析油、下扬子海相原油进行了对比。该凝析油碳同位素为-28．8‰—30．5‰，全油色谱中含有一定的长使正构烷烃，Pr/Ph为1．56，三环菇烷含量高，伽玛蜡烷含量低，重排甾烷含量高，C29甾烷＞＞C27甾烷＞C28甾烷。石蜡指数、庚烷值表明原油为高成熟凝析油，甲基菲指数MPI表明原油为未熟—低藏原油，C29甾烷20S／(20S 20R)值表明原油为成熟原油。这种成熟度的差异可能与不同成熟度原油的混合作用有关。油气主要充注时间为6—15Ma。凝析油的主体可能源于泰州组烃源岩，凝析油的形成与蒸发分信作用密不可分。     

乐安油田多期充注及生物降解作用对稠油黏度的影响分析北大核心CSCD

乐安油田稠油黏度高,开采难度大。该区原油遭受严重生物降解作用以及多期次油气充注影响,原油黏度差别较大。运用有机地球化学方法,对乐安油田8口井所采的9件油样进行了生物标志物特征分析,以研究生物降解作用和后期油气充注对原油物性造成的影响。研究表明,原油组分受生物降解作用改造明显,生物降解级别至少在6级以上,但是最终的组成成分以及原油黏度主要受后期油气充注作用影响。25-降藿烷与正构烷烃系列共存、重排甾烷和规则甾烷以及藿烷与25-降藿烷系列绝对含量的变化关系均说明乐安油田的原油属于生物降解和多期充注共同作用的混合原油,其绝对含量与生物降解作用和油气多期充注作用密切相关,因此通过对该区稠油的形成及控制因素加以分析,可为以后稠油的生产开发打好基础。     

乐安油田多期充注及生物降解作用对稠油黏度的影响分析

乐安油田稠油黏度高,开采难度大。该区原油遭受严重生物降解作用以及多期次油气充注影响,原油黏度差别较大。运用有机地球化学方法,对乐安油田8口井所采的9件油样进行了生物标志物特征分析,以研究生物降解作用和后期油气充注对原油物性造成的影响。研究表明,原油组分受生物降解作用改造明显,生物降解级别至少在6级以上,但是最终的组成成分以及原油黏度主要受后期油气充注作用影响。25-降藿烷与正构烷烃系列共存、重排甾烷和规则甾烷以及藿烷与25-降藿烷系列绝对含量的变化关系均说明乐安油田的原油属于生物降解和多期充注共同作用的混合原油,其绝对含量与生物降解作用和油气多期充注作用密切相关,因此通过对该区稠油的形成及控制因素加以分析,可为以后稠油的生产开发打好基础。     

南羌塘坳陷古油藏原油生物降解作用及意义

对南羌塘坳陷古油藏开展了有机地球化学分析, 从生物标志化合物特征和地质条件探讨古油藏生物降解特征及成藏期次。研究表明, 古油藏储层样品抽提物的正构烷烃分布完整, 但色谱基线发生不同程度抬升, 形成“鼓包”现象, 指示古油藏遭受了一定程度的生物降解作用; 古油藏族组分碳同位素发生“倒转”和普遍检出的25-降藿烷也证实了古油藏经历了中等-严重的生物降解。然而, 古油藏储层样品饱和烃色谱图显示出正构烷烃较为完整, 指示古油藏储层可能经历两期原油充注, 第一次原油遭受了生物降解, 第二期原油保留相对完整的正构烷烃。古油藏储层经历了两次原油充注, 与南羌塘坳陷富有机质页岩经历了两次生排烃的过程是一致。     

渤海湾盆地渤中凹陷原油地球化学特征研究

渤海湾盆地油气资源十分丰富、类型多样。通过对渤中凹陷19个原油样品地球化学特征的系统研究,揭示了该区不同类型、不同性质原油在物理性质、化学组成、生物标志物分布与组成、正构烷烃单体烃碳同位素等方面的差异。研究表明,渤中凹陷存在凝析油、正常油和生物降解原油。凝析油具有低密度、低粘度、低含蜡、饱和烃含量高,非烃、沥青质和芳烃含量低的特征,生物降解原油则反之。凝析油和生物降解原油中的重排补身烷丰度都大于8β（H）-补身烷的丰度,C24四环萜烷丰度低。渤中凹陷原油正构烷烃单体烃碳同位素组成分为两类：一类具有较轻的碳同位素组成,其同位素值介于-2．75％～-2．95％之间;另一类的碳同位素组成则较重,一般介于-2．40％--2．75％之间。     

北黄海盆地LV井侏罗系油砂抽提物地球化学特征

对北黄海盆地侏罗系两块含油砂岩的抽提物进行了常规的有机地球化学分析和碳同位素测试,结果表明它们具有不同的地球化学特征:埋藏较深的油砂抽提物属正常原油,饱和烃以正构烷烃为主,色谱图显示单峰型正态分布;而埋藏较浅的油砂抽提物,在饱和烃色谱图中有明显的UCM鼓包,同时含有完整的低碳数的正构烷烃、姥鲛烷和植烷,全油及族组成碳同位素分布范围广,为-24.7‰~-32.3‰,其中,全油及沥青质碳同位素偏重,饱和烃和芳烃碳同位素轻,反映出遭受了强烈的生物降解作用。与成熟度相关的生物标志物参数显示,原油已进入成熟—高成熟阶段。生物标志物和碳同位素组成表明,母质是在水体较浅的湖相环境下沉积的,受陆源高等植物和低等水生藻类的双源控制。综合判断,研究区存在两期油气充注。     

Molecular correlation of crude oils and oil components from reservoir rocks in the Tazhong and Tabei uplifts of the Tarim Basin, China

Molecular data from a large set of source rock, crude oil and oil-containing reservoir rock samples from the Tarim Basin demonstrate multiple sources for the marine oils in the studied areas of this basin. Based on gammacerane/C₃₁ hopane and C₂₈/(C₂₇ + C₂₈ + C₂₉) sterane ratios, three of the fifteen crude oils from the Tazhong Uplift correlate with Cambrian-Lower Ordovician source rocks, while the other crude oils from the Tazhong Uplift and all 39 crude oils from the Tahe oilfield in the Tabei Uplift correlate with Middle-Upper Ordovician source rocks. These two ratios further demonstrate that most of the free oils and nearly all of the adsorbed and inclusion oils in oil-containing reservoir rocks from the Tazhong Uplift correlate with Cambrian-Lower Ordovician source rocks, while the free and inclusion oils in oil-containing carbonates from the Tahe oilfield correlate mainly with Middle-Upper Ordovician source rocks. This result suggests that crude oils in the Tazhong Uplift are partly derived from the Cambrian-Lower Ordovician source rocks while those in the Ordovician carbonate reservoirs of Tahe oilfield are overwhelmingly derived from the Middle-Upper Ordovician source rocks.The scatter of C₂₃ tricyclic terpane/(C₂₃ tricyclic terpane + C₃₀ 17α,21β(H)-hopane) and C₂₁/(C₂₁ + ΣC₂₉) sterane ratios for the free and inclusion oils from oil-containing carbonates in the Tahe oilfield possibly reflects the subtle organofacies variations in the source rocks, implying that the Ordovician reservoirs in this oilfield are near the major source kitchen. In contrast, the close and positive relationship between these two ratios for oil components in the oil-containing reservoir rocks from the Tazhong Uplift implies that they are far from the major source kitchen.     

Molecular correlation of free oil,adsorbed oil and inclusion oil of reservoir rocks in the Tazhong Uplift of the Tarim Basin,China

The free, adsorbed and inclusion oils were recovered by sequential extraction from eleven oil and tar containing reservoir rocks in the Tazhong Uplift of Tarim Basin. The results of gas chromatography (GC) and GC–mass spectrometry analyses of these oil components and seven crude oils collected from this region reveal multiple oil charges derived from different source rocks for these oil reservoirs. The initially charged oils show strong predominance of even over odd n-alkanes in the range n-C₁₂ to n-C₂₀ and have ordinary maturities, while the later charged oils do not exhibit any predominance of n-alkanes and have high maturities. The adsorbed and inclusion oils of the reservoir rocks generally have high relative concentrations of gammacerane and C₂₈ steranes, similar to the Cambrian-Lower Ordovician source rocks. In contrast, the free oils of these reservoir rocks generally have low relative concentrations of gammacerane and C₂₈ steranes, similar to the Middle-Upper Ordovician source rocks. There are two interpretations of this result: (1) the initially charged oils are derived from the Cambrian-Lower Ordovician source rocks while the later charged oils are derived from the Middle-Upper Ordovician source rocks; and (2) both the initially and later charged oils are mainly derived from the Cambrian-Lower Ordovician source rocks but the later charged oils are contaminated by the oil components from the Silurian tar sandstones and the Middle-Upper Ordovician source rocks.     

The occurrence of ultra-deep heavy oils in the Tabei Uplift of the Tarim Basin,NW China

Deeply buried heavy oils from the Tabei Uplift of the Tarim Basin have been investigated for their source origin, charge and accumulation time, biodegradation, mixing and thermal cracking using biomarkers, carbon isotopic compositions of individual alkanes, fluid inclusion homogenization temperatures and authigenic illite K–Ar radiometric ages. Oil-source correlation suggests that these oils mainly originated from Middle–Upper Ordovician source rocks. Burial history, coupled with fluid inclusion temperatures and K–Ar radiometric ages, suggests that these oils were generated and accumulated in the Late Permian. Biodegradation is the main control on the formation of these heavy oils when they were elevated to shallow depths during the late Hercynian orogeny. A pronounced unresolved complex mixture (UCM) in the gas chromatograms together with the presence of both 25-norhopanes and demethylated tricyclic terpanes in the oils are obvious evidence of biodegradation. The mixing of biodegraded oil with non-biodegraded oil components was indicated by the coexistence of n-alkanes with demethylated terpanes. Such mixing is most likely from the same phase of generation, but with accumulation at slightly different burial depths, as evidenced by overall similar oil maturities regardless of biodegradation level and/or amount of n-alkanes. Although these Ordovician carbonate reservoirs are currently buried to over 6000 m with reservoir temperatures above 160 °C, no significant secondary hydrocarbon generation from source rocks or thermal cracking of reservoired heavy oil occur in the study area. This is because the deep burial occurred only within the last 5 Ma of the Neogene, and there has not been enough heating time for additional reactions within the Middle–Upper Ordovician source rocks and reservoired heavy oils.     

柴达木盆地西部油族划分及成因研究

对柴达木盆地西部各油田的151个原油进行了分子地球化学分析,并选取伽马蜡烷/C30藿烷、升藿烷指数、甾烷C27/C29和三环萜烷/C30Hop四个参数作为变量进行SAS聚类分析。结合常规二维散点图法,柴西原油可以分为3个油族7个亚族：油族Ⅰ以强水体分层、强还原环境为特征,主要分布于西端的七个泉、红柳泉地区,该油族可以分为两个亚族,油亚族②相比于油亚族①具有更高的甾烷 C27/C29比值;油族Ⅱ主要分布于狮子沟、花土沟、跃进和南翼山油泉子地区,在七个泉、红柳泉等地区也有分布,以相对较强的水体分层、还原环境为特征;油族Ⅲ主要分布于东（南）部的切克里克、乌南、绿草滩、咸水泉、跃西和跃进Ⅱ号等地区,以水体分层变差、较还原环境为特征,该油族可以分为3个亚族,其中油亚族⑤则具有异常低的三环萜烷/C30Hop 比值,油亚族⑥具有异常高的甾烷 C27/C29比值,油亚族⑦则具有异常高的三环萜烷/C30Hop 比值。油族空间分布特征受下干柴沟组源岩有机相在空间上的变化制约,下干柴沟组源岩发育时期,自西向东地层沉积速率增大,水体的分层变差、还原性降低,导致陆源输入的增加以及有机质保存条件变差。     

银额盆地查干凹陷原油地化特征及油源对比

银额盆地东部查干凹陷首次发现轻质低硫成熟原油，其饱和径含量在90％以上，成熟度相当于镜煤反射率Ro1．0％左右，是生油高峰阶段的产物；原油全碳同位素δ^13C值－31．1‰。原油生物标志物中类异戊二烯含量较高，植烷与姥皖烷均势；三环萜烷含量高于五环萜烷；含有较高的TS C29、Ts、C30重排藿烷、伽马蜡烷；藿烷中以C50藿烷为主，C32以上升藿烷含量极低；孕甾烷含量高；甾烷中以C29甾烷为主，C27甾烷含量也较高，异胆甾烷含量高于胆甾烷；重排甾烷含量低；甾烷的含量与萜烷含量相当，是典型的湖相原油。已发现的天然气中甲烷含量达80％，为湿气。原油和源岩生物标志物组成特征分析对比表明下白垩统巴音戈壁组源岩是主要油源岩。生物标志物特征示原油具有一定的运移效应。     

东濮凹陷原油、油砂抽提物与油气包裹体地球化学对比及其意义

通过对东濮凹陷桥口构造Q27井和Q55井原油、油砂抽提物和油气包裹体族组成和分子地球化学对比．可以发现：(1)油砂抽提物由于含蜡量高，非烃、沥青质含量低，其饱和烃、芳烃含量甚至比原油高，非烃、沥青质含量甚至比原油低；(2)Q27原油样与从同一井段内采取的油砂抽提物甾、萜烷分布特征存在着较为明显的差异，表明采油井段的原油地球化学组成是不均一的；(3)两口井的油气包裹体甾、萜烷分子指标，包括油源指标和成熟度指标，与油砂抽提物和原油也均有明显的差异，表明在油气注入过程中原油的油源和成熟度是不断变化的。尽管该地区的原油均来自沙三段，但在不同时间注入的原油可能来自不同“亚层”或“不同分布区域”的沙三段烃源岩。     

塔里木盆地一类新海相原油的地球化学特征

对塔中52等井奥陶系储层产出的原油进行的分析结果表明,它们的三环萜烷系列较为特殊,主要表现为其相对丰度呈C19>C20>C21>C23>C24>C25>C26阶梯状的模式,C24四环萜烷异常丰富,且其丰度远高于C26三环萜烷,这一分布模式一般出现在淡水沼泽相和浅湖相沉积地层与原油中。在三萜烷分布特征上,其伽马蜡烷含量很低,甾烷系列和藿烷系列的分布与组成特征与该地区来源于中上奥陶统烃源岩的海相原油十分接近,同时它们的全油均具有轻的碳同位素组成,其δ13Ｃ值都小于-30‰,具有海相成因原油的特征。而塔中12井上奥陶统良里塔格组4-5段烃源岩中生物标志物的分析结果进一步证实了该类原油与那些富含宏观藻残片,且有机质类型偏腐殖型的上奥陶统海相烃源岩关系密切,是该地区油气勘探中值得关注的对象。      

塔河油田原油甾藿烷系列化合物地球化学再认识

生物标志化合物是油气油源、成熟度、运移等领域研究中的一项得力工具。运用生物标志物色谱质谱技术，对比研究了塔河油田各油区原油生物标志化合物中甾、藿烷系列化合物特征。研究表明，塔河油田为一由晚期成熟高、轻微改造的原油与早期成熟度低、遭受较强降解原油混合而成的复合油藏，该油藏各区原油C27—C29甾烷同系物以及C27—C29重排甾烷特征反映出该区不同成熟度原油来自同一母源，原油Ts/(Tm+Ts)、重排甾烷/规则甾烷和ββ/(ββ+αα) C29比值关系立体图指示出原油的充注方向，印证了“塔河地区的油气主要来自于南部的满加尔坳陷”这一论点。