柴达木盆地西部七个泉与咸水泉油田原油地球化学特征对比研究

通过对取自七个泉油田和咸水泉油田原油样品中各类生物标志物的分布与组成特征的对比,发现七个泉油田原油中正构烷烃系列比较完整且丰度较高,而咸水泉油田原油中正构烷烃因轻微生物降解而被部分消耗,导致咸水泉油田原油的Pr/nC₁₇值和Ph/nC₁₈值明显高于七个泉油田原油。2个油田原油均呈现较强烈的植烷优势,七个泉油田原油的姥/植比更低,表明它们都来源于强还原环境下形成的烃源岩。在生物标志物分布与组成特征上,七个泉油田原油甾烷的C₂₇/C₂₉>1,而咸水泉[JP2]油田原油甾烷的C₂₇/C₂₉值均为0.8,意味着七个泉油田原油中浮游植物贡献高于咸水泉油田。咸水泉油田原油的C₂₉甾烷ααα20S/（ααα20S＋ααα20R）值和重排补身烷含量高于七个泉油田原油,暗示咸水泉油田原油成熟度比七个泉油田原油成熟度高。2个油田的长链藿烷序列均比较完整,伽马蜡烷含量也较高,对比长链藿烷和伽马蜡烷的丰度发现咸水泉油田原油的长链藿烷和伽马蜡烷丰度都比七个泉油田原油低,说明咸水泉油田原油形成的环境的盐度和还原性比七个泉油田原油弱。     

柴达木盆地原油烃类地球化学特征

柴达木盆地是我国重要的中新生代含油气盆地。已发现的18个油田分布于柴北地区和柴西地区,且以柴西地区最多。两个地区原油的成因截然不同,引起了国内外学者的关注。对采集于两地区13个油田的16个原油样品中烃类生物标志化合物进行了系统的分析,研究了它们的地球化学特征。生物标志化合物的分布和组成特征指示了西部原油形成于强还原咸水—超咸水湖相,北部原油形成于弱氧化淡水湖沼相;西部原油的母质主要为菌藻类,北部原油更多的来自陆源高等植物。根据生物标志化合物特征,并结合碳同位素组成,将柴达木盆地原油划分为两大类7种次级成因类型。     

柴达木盆地西部第三系油田水水文地球化学特征

柴达木盆地西部第三系油田水具有高矿化度特征,钾、硼、锂等离子达到工业开采品位,氢同位素值分布在-75.61‰~13.35‰,氧同位素值分布在-7.68‰~10.58‰。综合分析油田水化学成分、水化学参数组合以及氢氧同位素特征推断：柴达木盆地西部第三系油田水起源于大气降水,为典型陆相成因,为大气降水沿深大断裂下渗并经历了“深循环”作用形成,同时有深源岩浆流体的参与。油田水高矿化度特征与盐类矿物溶解和蒸发浓缩有关,钾、硼、锂等元素受深源流体控制,Ca²⁺和HCO₃^-主要来源于碳酸盐矿物溶解,油田水高Ca²⁺、低Mg²⁺的特征与演化过程中白云石交代方解石以及方解石溶解有关,充分的水-岩反应与深源流体的加入导致柴达木盆地西部第三系深成CaCl₂型油田水的形成。同时,初步推断南翼山地区第三系可能具有找钾意义。     

柴达木盆地尕斯库勒油田原油饱和烃地球化学特征及成因研究

尕斯库勒油田是柴达木盆地最大的油田,通过GC\|MS分析技术,系统剖析了尕斯库勒油田原油的地球化学特征。研究结果表明：正构烷烃呈偶奇优势,其中浅部油藏中有部分原油正构烷烃缺乏,遭受到轻度的生物降解。对于正常原油,均具有较低的姥植比,同时具有含量丰富的伽马蜡烷和C₃₅升藿烷,揭示了原油形成于强还原咸水环境,对比深部E¹₃油藏和浅部N₁-N¹₂油藏,浅部油藏的成油环境的古盐度略低于深部油藏;原油中C₂₁-/C₂₂+值在1.02~1.71之间,且具有高含量的C₂₇甾烷,指示了其母质来源以菌藻类低等水生生物为主;原油中C₂₉αββ/（αββ+ααα）值以及Ts/Tm值都较低,都表现出了低熟油的特征,同时C₂₉20S/（20S+20R）值普遍偏低,在深部E¹₃油藏该值分布在0.31~0.40之间,而在浅部N₁-N¹₂油藏该值相对较低,分布在0.29~0.36之间,深部油藏的成熟度略高于浅部油藏。     

柴达木盆地西部南区第三系原油成熟度特征

原油成熟度特征是原油地球化学研究的重要组成部分。通过对柴达木盆地西部南区第三系原油的色谱-质谱分析,在饱和烃和芳烃成熟度参数、生物标志物绝对浓度和热不稳定化合物的定量与定性分析基础上,详细剖析了该区原油的成熟度特征。研究结果表明:柴达木盆地西部南区第三系原油主体为未熟-低熟油,不存在混源造成未熟-低熟假象的可能性。成熟原油仅出现在花土沟、狮子沟和砂西地区。柴达木盆地西部南区有效烃源岩的发育特征,佐证了大量未熟-低熟原油存在的可能性。     

鄂尔多斯盆地吴起地区长9段和长10段原油地球化学特征对比

鄂尔多斯盆地吴起地区延长组长9油层组和长10油层组的源储特征存在较大争议。针对这一问题,通过地球化学测定方法,对该地区长9段原油和长10段原油的地球化学特征进行了精细对比和解剖,研究发现：长9段原油地球化学特征变化较大,其正构烷烃具有双峰和单峰2种类型,C₂₇-C₂₉甾烷呈倒“L”型分布,表现出明显的高等植物输入特征,说明母质来源广泛。长10段原油正构烷烃呈单峰分布,C₂₇-C₂₉甾烷呈“V”型分布,母质来源基本上均为水生微生物,并且来源集中。结合碳同位素特征判断长9段-长10段原油形成于淡水弱还原-弱氧化环境中。综合以上特征推断出长9段原油和长10段原油可来源于不同的烃源岩。它们具有完全不同、相对独立的油源。长9段原油部分来自长7段上部烃源岩。该发现将为延长组下组合的成藏机理研究提供帮助。     

正,异构烷烃在加水热解实验中的演化特征

塔里木盆地轮南地区三叠系低成熟生油岩干酪根进行加水热解后的产物中饱和烃分布参数与未热解生油岩相比，发生了较大变化：异构烷烃比值上升；加入蒙脱石的样品正构烷烃碳数分本范围前移：引人注目的是，生油岩抽提物中的姥鲛烷优势热解后转变为植烷优势。     

柴达木盆地西部地区原油地球化学特征及油源对比

柴达木盆地西部地区(简称柴西)新生界蕴藏着十分丰富的油气资源,勘探前景良好。根据原油和烃源岩中的生物标志物组成特征,对柴西原油的成熟度、沉积环境及生物来源等进行了探讨,从而进行原油成因类型划分以及油源对比。研究发现柴西原油显示出低成熟-成熟原油的特征且形成于水体盐度较高的还原性环境,有机质来源为混合源,低等水生植物输入量较大。根据原油的沉积环境、母质来源和成熟度特征,柴西原油可划分为4类:Ⅰ类来自于狮子沟-跃进地区,伽马蜡烷含量高,姥植比低,具有C27甾烷优势,有"翘尾"现象;Ⅱ类来自于切克里克-扎哈泉及南翼山-油泉子一带,伽马蜡烷含量较Ⅰ类低,具有C27甾烷优势,无"翘尾"现象;Ⅲ类来自于大风山、黄瓜峁等地区,具有C29甾烷优势,无"翘尾"现象;Ⅳ类来自于开特米里克地区,伽马蜡烷含量较前3类低,具有C27甾烷优势,无"翘尾"现象。油源对比结果表明,柴西原油主要来自E3和N1烃源岩。     

渤南洼陷沙四下段红层原油地球化学特征及油源探讨

根据GC、GC-MS等分析结果表明,渤南洼陷沙河街组四段下亚段原油正构烷烃分布呈单峰形态,高碳数C22—C34范围内具有明显偶碳优势,类异戊二烯烷烃呈植烷优势,伽马蜡烷、4-甲基甾烷、孕甾烷和升孕甾烷含量较高,重排甾烷不发育,C35升藿烷丰度明显高于C34升藿烷,芳烃中三芳甾烷的含量较高,三芴系列中硫芴含量丰富,均表明源岩沉积于富硫的强还原的半咸化—咸化湖相环境,并且C2920S/(20S+20R)值分布在0.49~0.55之间,属于典型的成熟油。通过油源对比认为沙河街组四段下亚段红层原油来自该区沙河街组四段上亚段烃源岩。     

大民屯凹陷高蜡原油的正构烷烃分析

利用ＨＰ６８９０型高温气相色谱剖析辽河盆地大民屯凹高蜡原油。研究结果表明：高蜡原油中显著存在碳数高达Ｃ４０－Ｃ６０以上的高碳数烷烃类，主要为正构烷烃；常敢相色谱受到柱系统热稳定性的限制，仅能提供碳数 小于Ｃ３５的化合物信息，而高温气相色谱可以分析Ｃ３５以上的烷烃。     

Compositional variabilities among crude oils from the southwestern part of the Qaidam Basin, NW China

A suite of crude oils have been analyzed by GC/MS in order to understand compositional heterogeneities in the oilfields located in the southwestern part of the Qaidam Basin, NW China. The oil samples investigated in this study can be grouped into two broad groups, A and B, based on the distributions of pentacyclic triterpanes. Group A oils predominately occurred in the northwestern part of the study area contain relatively high amounts of gammacerane and C₃₅ hopanes with the ratio of gammacerane to C₃₀ hopane (G/H) > 0.7 and the C₃₅/C₃₄ hopane ratio (C₃₅/C₃₄) > 1.2. In contrast, Group B oils mainly occurred in the southeastern part of the study area have relatively low values of G/H (~ < 0.7) and C₃₅/C₃₄ (< 1.2). Furthermore, Group A oils can be subdivided into three subgroups (A1, A2, and A3) by detailed investigation of molecular compositions of steranes, hopanes and aromatic sulfur compounds. Subgroup A1 oils, which mainly occurred in the westernmost corner, contain low amounts of dibenzothiophene (DBT) and methyldibenzothiophenes (MDBT) relative to C₃₀ hopane with the ratio of (DBT + MDBT)/C₃₀ hopane (DBT + MDBT/H) < ~ 0.25 and display high abundances of ααα20R C₂₈ sterane relative to C₂₉ compound with the C₂₈/C₂₉ sterane ratio > ~ 0.90. In contrast, subgroup A3 oils, which mainly occurred in depression areas, have relatively high values of (DBT + MDBT)/H (~ > 0.25) and relatively low ratios of C₂₈/C₂₉ sterane (~ < 0.90). Subgroup A2 oils, occurring in Gasikule and nearby oilfields, seem to have intermediate amounts of aromatic sulfur compounds and C₂₈ steranes relative to A1 and A3 oils, indicating a mixing signature of the two subgroups. The oil groups or subgroups revealed by the compositional heterogeneities and genetic affinities, as well as their regular occurrence in different oilfields, may indicate secondary petroleum systems existing within the Tertiary saline lacustrine petroleum in the southwestern Qaidam basin.     

Geochemical characterization of aromatic hydrocarbons in crude oils from the Tarim,Qaidam and Turpan Basins, NW China

Based on the systematic study of aromatic hydrocarbons in over 100 crude oil samples collected from the Tabei and Tazhong uplifts in the Tarim Basin, the western depression area in the Qaidam Basin and the Tabei depression in the Turpan Basin, the geochemical characteristics of the marine (Tarim Basin), saline lacustrine (Qaidam Basin), and swamp (Turpan Basin) oils were investigated. The marine oils from the Tarim basin are characterized by relatively low abundance of diaromatic hydrocarbons such as biphenyl and naphthalene, and relatively high abundance of triaromatic hydrocarbons including phenanthrene, dibenzothiophene and fluorene. In contrast, the swamp oils from the Turpan Basin are dominated by the highest relative abundance of diaromatic hydrocarbons and the lowest relative abundance of triaromatic hydrocarbons in all the oil samples in this study. The relative abundance of diaromatic and triaromatic hydrocarbons in the saline lacustrine oils from Qaidam Basin is between that in Tarim oils and Turpan oils. Aromatic parameters based on the isomer distributions of dimethylnaphthalenes (DMN), trimethylnaphthalenes (TMN), tetramethylnaphthalenes (TeMN) and methylphenanthrenes (MP), i.e., 1,2,5-trimethylnaphthalene(TMN)/1,3,6-TMN ratio, 1,2,7-TMN/1,3,7- TMN ratio, (2,6- +2,7-)-dimethylnaphthalenes (DMN)/1,6-DMN ratio, 1,3,7-TMN/(1,2,5- +1,3,7-)-TMN, 1,3,6,7-TeMN/(1,3,6,7- +1,2,5,6- +1,2,3,5-)-TeMN ratio and MP index, may reflect the diversity of organic source input, thermal maturity and depositional environments. In addition, the dibenzothiophenes (DBTs)/fluorenes(Fs) and dibenzofurans (DBFs)/Fs ratios were found to the very useful and effective in determining genetic types of crude oils for the marine, saline lacustrine, and swamp depositional environments, and for oil-oil correlations.     

Geochemical characterization of aromatic hydrocarbons in crude oils from the Tarim,Qaidam and Turpan Basins,NW China

Based on the systematic study of aromatic hydrocarbons in over 100 crude oil samples collected from the Tabei and Tazhong uplifts in the Tarim Basin, the western depression area in the Qaidam Basin and the Tabei depression in the Turpan Basin, the geochemical characteristics of the marine (Tarim Basin), saline lacustrine (Qaidam Basin), and swamp (Turpan Basin) oils were investigated. The marine oils from the Tarim basin are characterized by relatively low abundance of diaromatic hydrocarbons such as biphenyl and naphthalene, and relatively high abundance of triaromatic hydrocarbons including phenanthrene, dibenzothiophene and fluorene. In contrast, the swamp oils from the Turpan Basin are dominated by the highest relative abundance of diaromatic hydrocarbons and the lowest relative abundance of triaromatic hydrocarbons in all the oil samples in this study. The relative abundance of diaromatic and triaromatic hydrocarbons in the saline lacustrine oils from Qaidam Basin is between that in Tarim oils and Turpan oils. Aromatic parameters based on the isomer distributions of dimethylnaphthalenes (DMN), trimethylnaphthalenes (TMN), tetramethylnaphthalenes (TeMN) and methylphenanthrenes (MP), i.e., 1,2,5-trimethylnaphthalene(TMN)/1,3,6-TMN ratio, 1,2,7-TMN/1,3,7-TMN ratio, (2,6-+2,7-)-dimethylnaphthalenes (DMN)/1,6-DMN ratio, 1,3,7-TMN/(1,2,5- +1,3,7-)-TMN, 1,3,6,7-TeMN/(1,3,6,7- +1,2,5,6- +1,2,3,5-)-TeMN ratio and MP index, may reflect the diversity of organic source input, thermal maturity and depositional environments. In addition, the dibenzothiophenes (DBTs)/fluorenes(Fs) and dibenzofurans (DBFs)/Fs ratios were found to the very useful and effective in determining genetic types of crude oils for the marine, saline lacustrine, and swamp depositional environments, and for oil-oil correlations.     

柴达木盆地北缘南八仙油气藏的蒸发分馏作用

对南八仙油气藏E₃¹与N₂²—N₁油层油气地球化学特征和油源的关系进行了分析,根据油气分异作用与其组成变化的相互关系研究了该油气藏的蒸发分馏作用,并从地质构造背景和油气及其烃源岩地化特征方面探讨了其成因机制.研究结果表明,虽然南八仙油气藏E₃¹与N₂²—N₁两层系的原油对比表明两者是同源,但它们在轻烃组成和正构烷烃系列分布上存在显著差异.E₃¹原油轻烃中正烷烃含量很少,而芳烃化合物含量异常高,其正烷烃摩尔分数对数曲线为折点在nC₁₀的折线,表明其经历了强烈的蒸发分馏作用.而N₂²—N₁原油轻烃中正烷烃占优势,高碳数化合物较少,说明该层原油是从E₃¹油气层通过蒸发分馏作用向上运移而来.该含油气构造带的断裂系统和高成熟的油气及其煤系烃源岩是导致蒸发分馏作用的主控因素     

Geochemical characterization of sediments samples of Sembar Formation from three different wells of Southern Indus Basin

Sediment samples from three boreholes namely Paniro-II, North Akri, and Bhadmi of Sembar Formation, Southern Indus Basin were geochemically analyzed. The Soxhlet extracted bitumen were fractionated by column chromatography. The saturate fractions were further analyzed to evaluate type and quality of organic matter (OM). Total organic carbon, determined by a wet combustion titration method, indicates fair-to-good source rock potential. The plot of isoprenoids/n-Alkanes shows a mixed source of OM. Pristane/Phytane values and distribution of hydrocarbons showed dysoxic depositional environment. Carbon preference indices suggested increase in maturity with depth.     

The study of the oil source in Xiaoliangshan Sag,Northwestern Qaidam Basin,China

The geochemical characteristics of the crude oil in the northwestern and southwestern Qaidam Basin and the Tertiary source rocks of Xiaoliangshan Sag were compared and analyzed. The results show that the Tertiary source rocks of N₁ and E₃² are the best two sets of source rocks in Xiaoliangshan Sag. The crude oil of the northwestern Qaidam Basin is sourced from nearby Xiaoliangshan Sag rather than Mangya Sag. The crude oil of N₂² in the shallow strata of Nanyishan, Jiandingshan and Xiaoliangshan are mainly sourced from the source rocks of N₁, while the crude oil of E₃² in the deep strata is mainly sourced from the source rocks of E₃².     

Prediction of asphaltene precipitation from n-alkane diluted crude oil by using PC-SAFT equation of state

The precipitation tendency of heavy organics such as asphaltene has posed great challenges for petroleum industry, and thus study of asphaltene precipitation amount and formation conditions seems to be necessary. One of the most common approaches for prediction of asphaltene precipitation is using thermodynamic models. In this study a PC-SAFT equation of state (EOS) is used to predict asphaltene precipitation in two Iranian dead oil samples. Asphaltene content is obtained by filtration method of the oil samples diluted with specific concentrations of different normal alkanes. Also liquid-liquid equilibrium is used for characterization of oil sample into one heavy phase (asphaltene) and another light phase (saturates, aromatics, and resin). Calculations show that the developed model is highly sensitive to interaction parameter between oil fractions. Prediction results were improved due to using Chueh-Prausnitz equation. The results indicate good potential of PC-SAFT EOS in the prediction of asphaltene precipitation in crude oil samples diluted with different normal alkanes. The model error is <5% and the model precision is increased by reducing the number of normal alkane carbons.     

莺-琼盆地原油的蒸发分馏作用

根据油气分异作用与其组成变化的相互关系研究莺-琼盆地油气藏的蒸发分馏作用，从地质背景和油气及其烃源岩地化特征方面探讨其成因机制。研究表明．莺-琼盆地发育的大量泥底辟构造以及天然气幕式运移为油气蒸发分馏作用提供了基本地质条件。原油分异常高的苯、甲苯以及二甲苯等芳烃化合物．但低碳数烃类有损失；正构烷烃摩尔分数对数曲线上有明显的折点．表明其经历过强烈的蒸发分馏作用．并引起原油地化特征的差异。油气藏经蒸发分馏作用后将形成残余的富含芳烃的“母体”和运移聚积后富舍轻烃的“子体”．但目前发现的油气藏以前者为主．寻找“子体”油气藏将是下一步的勘探方向。图1参12     

哈拉哈塘凹陷奥陶系原油芳烃生物标志物特征及油源

哈拉哈塘凹陷是近些年的勘探热点地区,为了进一步明确其原油母源输入、沉积环境、成熟度和可能烃源层,对26个哈拉哈塘凹陷和塔河奥陶系原油样品、4个台盆区烃源岩样品进行了系统的芳烃生物标志物分析。研究结果表明,哈拉哈塘原油均具有高萘、高菲、低联苯、贫1,2,5-和1,2,7-三甲基萘而富1,3,6-三甲基萘、高4-MDBT/DBT和（2+3）-MDBT/DBT比值、轻芳烃碳同位素的特点,与塔河奥陶系原油非常相似,反映出其属于典型的海相成因,且以低等藻类和细菌占生源优势。高丰度的二苯并噻吩和较低的DBT/P、Pr/Ph比值,指示其源岩沉积于强还原的碳酸盐沉积环境。等效镜质体反射率R_c1和R_c2揭示哈拉哈塘原油成熟演化处于中等-较高范畴。甲基三芳甾烷异构体组成型式对比表明,中-上奥陶统烃源岩与哈拉哈塘和塔河奥陶系原油对比良好,推测其为本区奥陶系原油的烃源层。