梨树断陷秦家屯-七棵树油田原油饱和烃地球化学特征研究

松辽盆地梨树断陷秦家屯-七棵树地区是该盆地中生界油气勘探新区,对该地区原油的地球化学特征进行研究,了解原油的成因,可以为该地区石油勘探和开发提供科学依据。利用相关分析资料;对采集于秦家屯-七棵树油田原油的饱和烃生物标志化合物进行了系统剖析,揭示了其地球化学特征与成因类型。结果表明:梨树断陷秦家屯-七棵树地区存在3种类型的原油:Ⅰ类原油储存于秦家屯油田的泉头组与登娄库组,来源于半咸水湖相沉积环境的源岩;Ⅱ类原油储层于沙河子组,来源于弱还原环境半咸水湖相沉积环境且富含黏土矿物的源岩;而Ⅲ类原油是混源油,是上述两种原油混合的产物。     

柴达木盆地西部原油地球化学特征对比

柴达木盆地西部地区各油田所产原油在成因上大多属咸水湖相,因而具有咸水湖相成因原油某些共同的地球化学特征,如低的姥植比和正构烷烃的偶碳优势等。对比后发现,柴西南区所产原油在正构烷烃系列分布特征上基本都具有nC 37 优势、姥植比相对较低且伽马蜡烷含量丰富,而柴西北区所产原油则在正构烷烃系列分布特征上大多没有nC 37 优势、姥植比相对偏高且伽马蜡烷含量明显偏低,这表明柴西南区与北区的原油其烃源岩具有不同的地球化学特征。依据原油中的nC 37 优势与姥植比之间负相关、与伽马蜡烷指数之间正相关这一现象,推测原油中正构烷烃系列的nC 37 优势主要受控于沉积环境的性质,高盐度和强还原的沉积环境是导致原油中出现nC 37 优势的主要地球化学因素。     

渤海海域低成熟油的地球化学特征

渤海海域存在半咸水—咸水环境成因和淡水—微咸水湖相成因的两种低成熟油。半咸水—咸水环境主要分布于辽东湾、渤中凹陷东北缘和沙南凹陷。淡水—微咸水成因的低成熟油主要分布于歧口凹陷及沙南凹陷西北缘。不同成因类型的低成熟油的原油物性、族组分组成及生物标志化合物组成与分布特征等存在差异。沙河街组一段烃源岩为半咸水—咸水环境成因低成熟油的主要贡献者 ,而淡水—微咸水湖相成因的低成熟油主要来源于沙河街组三段和东营组下段烃源岩     

渤海海域低成熟油的地球化学特征

渤海海域在半咸水－咸水环境成因和淡水－微咸水湖相成因的两种低成熟油。半咸水－咸水环境主要分布于辽东湾，渤中凹陷东北缘和沙南凹陷。淡水－微咸水成因的低成熟油主要分布于岐口凹陷及沙南凹争西北缘。不同成因类型的低成熟油的原油物性，族组分组成及生物标志化合物组成与分布特征等存在差异。沙河街组一段烃源岩为半咸水－咸水环境成因代成熟油的主要贡献，而淡水－微咸水湖相成因的低成熟油主要来源于沙河街组三段和东营组下段烃源央。     

冀中地区文安油田原油非均质性及其意义

通过全油GC/MS分析,揭示了冀中地区文安油田分子组成上的非均质性。研究认为,文安油田至少存在两类不同成因类型的原油（Ⅰ类和Ⅱ类）。Ⅰ类原油具有较高的甾/藿比,生物标志化合物（甾烷、伽马蜡烷、4-甲基甾烷）含量相对较高,芳香族化合物（甲基菲、三芳甾烷以及甲基二苯并噻吩）含量相对较低;Ⅱ类原油具有较低的甾/藿比,生物标志化合物含量相对较低,芳香族化合物含量相对较高。两类原油的分布具有规律性:Ⅰ类原油分布于南区的议论堡构造带;Ⅱ类原油分布于北区的史各庄构造带。研究表明,文安油田至少存在两个油气富集体系。     

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。     

鄂尔多斯盆地华庆地区延长组下油层组原油地球化学特征及油源对比

华庆地区位于鄂尔多斯盆地的湖盆中心,是鄂尔多斯盆地超低渗油藏勘探开发的重点地区之一。系统采集了华庆地区延长组长8、长9和长10等油层组原油和长7段烃源岩\,长8段烃源岩样品,分析原油和烃源岩中生物标志化合物,研究生物标志化合物分布和组成,探讨原油的成因和油源问题。结果表明长8、长9和长10等油层组原油属于同一族原油,具有相同的成因,它们的油源均为长7段烃源岩。     

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。     

江陵凹陷不同地区原油地球化学特征及油源对比

以江汉盆地江陵凹陷古近系新沟嘴组下段为主要研究对象,通过对不同地区原油生物标志化合物的组成与分布特征的分析,结合油—油、油—源对比发现研究区原油全部显示出成熟原油的特征并且形成于水体较深,还原性相对较强的沉积环境。根据生物标志化合物参数之间的差异,将研究区原油分为2类：Ⅰ类原油来自于万城地区以及南部地区,此类原油升藿烷系列含量极低,成熟度高并且陆源有机质贡献少;Ⅱ类原油全部来自于荆州背斜带,成熟度低于Ⅰ类原油,存在部分陆源有机质贡献,升藿烷系列化合物存在一定丰度,并且位于荆州背斜带西北部原油成熟度要明显大于中部及东南部。油源对比结果显示,2类原油在不同区域可能存在不同层位的烃源岩贡献,万城地区X-Ⅲ层位和X-Ⅱ层位烃源岩为Ⅰ类原油主要的烃源岩,同时荆州背斜带北部X-Ⅱ层位烃源岩对其也存在一定贡献;Ⅱ类原油主要以荆州背斜带北部X-Ⅲ层位为主要的烃源岩,荆州背斜带北部X-Ⅱ层位也存在一定的贡献,并且分布于荆州背斜带的中部及东南部的Ⅱ₂类原油中可能还存在万城地区2个层位烃源岩的些许贡献。     

鄂尔多斯盆地富县地区延长组长6、长7段原油地球化学特征及油源对比

运用原油物性、族组成、生物标志化合物、油—源对比等分析指标,对鄂尔多斯盆地富县地区长6、长7段原油地球化学特征和油源成因进行了分析。富县地区长6、长7段原油物理性质相似,均为低密度、低黏度的轻质原油;原油饱和烃平均质量分数为71.46%,芳烃平均质量分数为13.27%,非烃及沥青质含量相对较低;原油“饱芳比”值较高,平均值为5.43;正构烷烃呈单峰分布,低碳数占优,主峰碳为nC₁₅;生物标志化合物中C₃₀藿烷优势明显;规则甾烷构型均呈反“L”字形分布特征,以C₂₉为主;原油成熟度相近,均为成熟原油;生油母质以低等水生生物为主,含部分陆生高等植物,沉积于弱还原的淡水—微咸水陆相沉积环境;油源对比分析表明,长6、长7段原油与本区长73亚段烃源岩亲缘关系较好,而与长7段上部暗色泥岩及湖盆中心志丹长73亚段烃源岩对比性较差,亲缘关系不明显,因此,认为原油主要来自于本区长73亚段烃源岩。      

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。     

BIOMARKER GEOCHEMISTRY OF CRUDE OILS FROM THE QAIDAM BASIN, NW CHINA

A suite of 16 crude oil samples from 13 oilfields in the Qaidam Basin were analyzed using techniques including gas chromatography and gas chromatography - mass spectrometry. Biomarker compositions and parameters were used to investigate the palaeoenvironmental and depositional conditions and to correlate the oils with eachother. Oils from the western Qaidam Basin have pristane/phytane (Pr/Ph) ratios of less than 0.7, and contain abundant gammacerane, C₂₇ steranes, 4-methyl steranes and long-chain tricyclic terpanes. C₂₉ sterane 20S/(20S+20R) and ββ/(ββ+αα) ratios show that the western Qaidam oils have variable maturities ranging from immature to mature. Oils from the northern Qaidam Basin, by contrast, have Pr/Ph ratios greater than 3, low gammacerane contents, and relatively abundant C₂₉ steranes, bicyclic terpanes and alkylcyclohexanes. C₂₉ sterane 20S/(20S+20R) and ββ/(ββ+αα) ratios indicate that the northern Qaidam oils are mature.
δ¹³C values, which range from -25.4‰ to -28.3‰ with the exception of one oil from the north (-3l.6‰), are similar for oils from both the northern and western parts of the Qaidam Basin. The oils'carbon isotope compositions are similar to those of the organic matter in potential source rocks.
The western Qaidam oils are inferred to have originated from Tertiary source rocks deposited under anoxic and saline-hypersaline lacustrine conditions with dominant algal organic matter. The northern Qaidam oils are interpreted to be derived from Jurassic source rocks which were deposited in a freshwater lacustrine environment and which are dominated by terrigenous organic matter.     

柴达木盆地北缘块断带原油的地化特征及油源问题

柴达木盆地北缘断层纵横交错,控制着本区的构造格局和中新生界地层的岩性和厚度,故称北缘块断带。其范围西起昆特依凹陷,东至旺尕秀地区,北界阿尔金山—祁连山山前断裂带,南邻葫芦山、埃姆尼克山一线,面积约三万平方公里(图1)。      

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.     

GEOCHEMISTRY OF CRUDE OILS,SEEPAGE OILS AND SOURCE ROCKS FROM BELIZE AND GUATEMALA: INDICATIONS OF CARBONATE‐SOURCED PETROLEUM SYSTEMS

This study reviews the stratigraphy and the poorly documented petroleum geology of the Belize‐Guatemala area in northern Central America. Guatemala is divided by the east‐west trending La Libertad arch into the North and South Petén Basins. The arch is the westward continuation of the Maya Mountains fault block in central Belize which separates the Corozal Basin in northern Belize from the Belize Basin to the south. Numerous petroleum seeps have been reported in both of these basins. Small‐scale oil production takes place in the Corozal Basin and the North and South Petén Basins. For this study, samples of crude oil, seepage oil and potential source rocks were collected from both countries and were investigated by organic geochemical analyses and microscopy. The oil samples consisted of non‐biodegraded crude oils and slightly to severely biodegraded seepage oils, both of which were generated from source rocks with similar thermal maturities. The crude oils were generated from marine carbonate source rocks and could be divided into three groups: Group 1 oils come from the North Petén Basin (Guatemala) and the western part of the Corozal Basin (Belize), and have a typical carbonate‐sourced geochemical composition. The oils correlate with extracts of organic‐rich limestones assigned to the Upper Cretaceous “Xan horizon” in the Xan oilfield in the North Petén Basin. The oils were generated from a single source facies in the North Petén Basin, but were charged from two different sub‐basins. Group 2 oils comprise crudes from the South Petén Basin. They have characteristics typical of carbonate‐sourced oils, but these characteristics are less pronounced than those of Group 1 oils. A mixed marine/lacustrine source facies deposited under strongly reducing conditions in a local kitchen area is inferred. Group 3 oils come from the Corozal Basin, Belize. A carbonate but also a more “shaly” source rock composition for these oils is inferred. A severely biodegraded seepage oil from Belmopan, the capital of Belize, resembles a nearby crude oil. The eastern sub‐basin in the North Petén Basin may potentially be the kitchen area for these oils, and for the seepage oils found in the western part of the Corozal Basin. The seepage oils from the Corozal and Belize Basins are moderately to severely biodegraded and were generated from carbonate source rocks. Some of the seepage oils have identical C_27–29 sterane distributions to the Group 2 oils, but “biodegradation insensitive” biomarker ratios show that the seepage oils can be divided into separate sub‐groups. Severely and slightly biodegraded seepage oils in the Belize Basin were probably almost identical prior to biodegradation. Lower Cretaceous limestones from the Belize Basin have petroleum generation potential, but the samples are immature. The kitchen for the seepage oils in the Belize Basin remains unknown.     

柴达木盆地东坪地区原油裂解气的发现及成藏模式

柴达木盆地东坪地区发现了中国陆上地质储量最大的基岩气田——东坪气田，其天然气来源于侏罗系高成熟-过成熟阶段的裂解气，但深层裂解气藏的成因较为复杂，特别是在东坪气田以西的坪西和尖顶山构造带，由于不发育侏罗系，新发现的基岩气藏来源不明，影响了深层天然气的勘探认识。利用天然气组分和同位素分析数据，结合东坪地区地质特征对深层裂解气开展分析，建立了天然气的成藏模式。研究表明，东坪地区深层基岩气藏具有原油裂解气，基岩储层中发育沥青包裹体，表明该地区发育古油藏裂解气。柴达木盆地北缘的侏罗系烃源岩以湖相泥岩为主，有机质丰度高、类型好，经历了长期的深埋过程，具备形成原油裂解气的物质基础和温度条件。东坪地区深层基岩气藏的成藏具有早期充油、后期高温裂解、晚期调整的特征。东坪地区原油裂解气的发现拓展了柴达木盆地北缘天然气的勘探领域，对深化柴达木盆地深层天然气勘探具有重要指导意义。     

柴达木盆地东坪地区原油裂解气的发现及成藏模式

柴达木盆地东坪地区发现了中国陆上地质储量最大的基岩气田--东坪气田,其天然气来源于侏罗系高成熟-过成熟阶段的裂解气,但深层裂解气藏的成因较为复杂,特别是在东坪气田以西的坪西和尖顶山构造带,由于不发育侏罗系,新发现的基岩气藏来源不明,影响了深层天然气的勘探认识。利用天然气组分和同位素分析数据,结合东坪地区地质特征对深层裂解气开展分析,建立了天然气的成藏模式。研究表明,东坪地区深层基岩气藏具有原油裂解气,基岩储层中发育沥青包裹体,表明该地区发育古油藏裂解气。柴达木盆地北缘的侏罗系烃源岩以湖相泥岩为主,有机质丰度高、类型好,经历了长期的深埋过程,具备形成原油裂解气的物质基础和温度条件。东坪地区深层基岩气藏的成藏具有早期充油、后期高温裂解、晚期调整的特征。东坪地区原油裂解气的发现拓展了柴达木盆地北缘天然气的勘探领域,对深化柴达木盆地深层天然气勘探具有重要指导意义。     

柴达木盆地西部地区致密油气形成条件和勘探领域探讨

在明确致密油气定义的基础上,分析了柴达木盆地西部(简称“柴西”)地区致密油气形成的地质条件:首先发育多套大面积的烃源岩,具有多个生烃凹陷;其次广泛发育致密储层,主要包括致密砂岩储层和裂缝型(泥质岩和碳酸盐岩)致密储层。致密砂岩储层以南翼山和红柳泉E¹₃砂岩、乌南N¹₂砂岩为代表;裂缝型致密储层以南翼山E²₃、狮子沟E¹₃、开特米里克和油泉子N₁的储层为代表;且源储交互叠置分布。致密油气在柴西地区广泛分布,古构造斜坡区和生油凹陷中心是致密油气分布集中区。致密油气可能的成藏组合包括源内包裹组合、源上广覆组合、源下依伏组合和源侧披覆组合等4种。按照储层成因类型,柴西地区致密油气勘探领域主要有:三角洲前缘砂体致密油气、滩坝和浊积扇砂体致密油气以及碳酸盐岩致密油气3个领域。针对每个领域,通过致密油气形成条件分析,按照区域和层位,共优选出8个有利勘探区带。       

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。