渤海湾盆地牛庄洼陷南斜坡油砂烃来源分析

对渤海湾盆地东营凹陷牛庄洼陷南斜坡不同埋深油砂及其相邻烃源岩的分析表明,埋深<2700m的油砂烃化学组成与相邻沙四段页岩抽提物有显著差异,两者不具相关性,油砂中的烃类主要为深部的运移烃。油砂烃具有常规油的气相色谱特征,而未熟-低熟页岩在高碳数部位有一明显的甾萜类等高分子量化合物未分辨鼓包,且正构烷烃奇偶优势明显;油砂烃含高丰度的"地质型"甾烷,而未熟-低熟页岩中C₂₉甾烷αββ20S含量甚微,但热稳定性低的化合物5β(H)甾烷及13α(H),14α(H)-三环萜烷含量较高;油砂烃几乎不含甲藻甾烷,而未熟-低熟页岩中含丰富的此类化合物。由深至浅,油砂烃成熟度依次降低,伽玛蜡烷相对含量增高,升藿烷"翘尾"现象变得明显。油砂烃的成熟度梯度及烃类组成的规律性变化不仅可以指示油气运移的大致方向,而且揭示出不同演化阶段烃源岩的生烃特征有别和/或油气运移过程中未熟-低熟烃源岩沥青的混合作用。      

陆东凹陷低熟油特征及形成条件分析

陆东凹陷白垩系所产原油多为低熟油。其特征为低含硫，中含蜡，凝固点中等，粘度中等，密度偏高，饱和烃含量低，芳烃非烃含量偏高。饱和烃色谱特征，生物标记化合物特征和稳定碳同位素组成特征均表明，菌藻类低等生物是重要的成烃母质。     

煤系烃源岩不同极性溶剂抽提物基本地球化学特征

正己烷、苯、二氯甲烷、氯仿4种不同极性溶剂抽提烃源岩的实验表明，溶剂极性对抽提物含量和化学组成影响很大。抽提物含量随溶剂极性增加而增加，但不同类型烃源岩抽提物含量变化幅度差异明显，其中湖相泥岩氯仿抽提物仅为正己烷抽提物的1.2～1．4倍，煤系泥岩为2～5倍，煤系炭质泥岩和煤为5～10倍。抽提物族组成分析表明，随溶剂极性增加，抽提物中饱和烃比例明显减少，芳烃比例略为减少，非烃和沥青质比例明显增加。正己烷抽提物的化学组成与煤系原油最相近，氯仿抽提物中饱和烃的含量明显偏低而非烃、沥青质含量明显偏高。抽提物中饱和烃含量定量计算表明，不同极性溶剂萃取的饱和烃质量相对于岩石质量变化很小，正己烷已经能够萃取出烃源岩中绝大部分饱和烃，极性强的溶剂并不能从煤中莘取更多的饱和烃。这可能意味着虽然煤的氯仿抽提物组成与煤系原油化学组成存在很大差异，但不影响煤的正构烷烃组成，也就可能不影响抽提物与煤系原油生物标志物之间的对比。图4表1参19     

鄂尔多斯盆地镇北地区油源对比及石油运移方向

根据原油和烃源岩饱和烃、芳香烃的色谱-质谱分析,原油和油砂抽提物的咔唑类含氮化合物分布特征,结合砂体展布探讨了鄂尔多斯盆地镇北地区长81小层原油来源和石油运移方向.结果表明,镇北地区长81小层原油均来自于长73小层烃源岩,特点是三环萜烷以C23为主峰呈正态分布,缺失伽马蜡烷,孕甾烷发育,重排甾烷丰度低.原油在成熟度上有所差异,靠近深湖区的原油成熟度较高;原油和油砂抽提物的咔唑类含氮化合物有一定的运移分馏效应,石油从生烃中心沿砂体向西南方向运移.     

含油页岩不同极性试剂连续抽提物饱和烃组成特征

页岩中不同赋存状态原油的分离成为当前较为关注的问题。采用极性逐渐增强的正己烷、二氯甲烷和三氯甲烷对祁连山木里煤田钻孔的含油页岩样品进行连续抽提,对各抽提物分别做族组分和定量色谱—质谱分析。研究结果表明:正己烷冷浸泡抽提物主要为页岩内自由态烃类,以饱和烃为主;而三氯甲烷索氏抽提物则主要为吸附态烃类,其中极性组分含量高,且碳数较高的正构烷烃丰度高;随溶剂极性的增加,连续抽提物生标参数C_(29)ααα甾烷20S/(20S+20R)与C_(24)四环萜烷/C_(26)三环萜烷比值逐渐增加,而C_(21)/C_(23)三环萜烷比值逐渐减小,但C_(23)三环萜烷/C_(30)藿烷和C_(31)升藿烷22S/(22S+22R)比值基本保持不变,另外部分参数比值则表现为无规律性的变化;尽管各种抽提物烃类组成和分子参数存在一定的差异,但各类化合物分布模式和部分参数值差异很小,表明3种连续抽提物(不同赋存状态的烃类)均为页岩内本源烃,而非外来烃。     

大民屯凹陷烃源岩中高分子量烃的形成与分布特征

大民屯凹陷原油以高含蜡著称,对沙河街组低成熟烃源岩抽提物的高温气相色谱分析揭示了高分子量化合物的组成与分布特征。研究表明有机质的原始组成和沉积环境是形成高分子量烃类的主要控制因素。有机质含量较高的烃源岩(TOC>3.0%)显微组成中类脂组的含量较高,岩石抽提物不仅总量较高,而且含蜡量较高,但在蜡的组成上以中分子量的显晶蜡为主,形成于弱还原环境。有机质含量较低的烃源岩(TOC<2.0%)显微组成中镜质组的含量较高,岩石抽提物含量及含蜡量均较低,但在蜡的组成上高分子量的微晶蜡相对富集,形成于弱氧化环境。除正构烷烃外,岩石抽提物中还检出了含量较高的异构烷烃。      

文留油田25东区块沥青垫地球化学特征及成因

利用薄层色谱和全烃色谱分析并结合测井响应特征，在文留油田25东区块鉴定出3层沥青垫，其测井响应特征与油层相似，对油藏起分隔作用，主要出现在高孔隙度、高渗透率的储集层中。沥青垫富含极性组分，其含量大于40％，远高于油层抽提物中极性组分的含量。饱和烃GC-MS分析结果显示，沥青垫、油层岩心抽提物和原油中正构烷烃及生物标志物组成特征具有相似性，说明其中的烃类来自相同的烃源岩，具有相似的热演化程度，且未受到强烈的生物降解作用。沥青垫地球化学特征和测井资料表明，油田地层水体的长期冲刷与氧化作用是沥青垫形成的主要原因，沥青垫存在于油、水交互部位。图9参8     

塔中地区油藏烃类组成的非均质性及其意义

利用岩石热解分析技术，薄层色谱-氢火焰检测技术，气相色谱分析技术，可以有效地表征油藏烃类组成的非均质性，塔中北斜坡石炭系油藏烃类组成东西端表现出共同性质，即总烃含量高，极性化合物丰度相对较低，含油率T值较高，表现出油层的特征。相反，中端各井尽管T值含量高，但羟类组成中，总烃含量低，沥青质含量高，表明该油藏曾遭受破坏。塔中北斜坡志留系油藏地球化学描述表征西端古油藏遭到较严重的生物降解作用，且后期轻质油的注入对此油藏影响较少；而东端古油藏原油没有发生生物降解作用，且后期轻质油的注入比较高，根据储集岩烃类正构烷烃的分布特征，塔中北斜坡石炭系油藏存在着两期充注过程，第一期充注的石油形成现今的沥青砂或油砂，而第二期充注的石油形成现今的主要产层。     

油藏非均质性及聚油史初探

本文利用热解和热蒸发气相色谱分析技术,研究了塔里木轮南油田三叠系油藏剖面上储层的含油性和原油组成变化,发现低孔渗层段油砂的含油性低,原油的成熟度较低,正烷烃呈前峰型分布;高孔渗层段含油性高,原油成熟度较高,正烷烃里后峰型分布;孔渗中等的油砂中含油性和原油组成性质介于两者之间。油藏中不同孔渗层段的这种原油组成非均质性能反映油藏的聚油史。      

苏北盆地盐城凹陷朱家墩气藏凝析油中的金刚烷类及其意义

盐城凹陷朱家墩气藏盐参1井阜一段储层所产凝析油与该井上白垩统泰州组成熟烃源岩在各类生物标志化合物的分布与组成特征上具有较好的相似性,表明它们在成因上存在相关性,但生物标志化合物成熟度参数显示凝析油的成熟度明显高于所研究的烃源岩。烷基单金刚烷类是原油和烃源岩中一类具有高热稳定性的烃类化合物,其中双金刚烷系列的热稳定性高于单金刚烷系列。分析结果表明:凝析油中不但存在烷基单金刚烷系列,同时也存在烷基双金刚烷系列,但在上白垩统泰州组烃源岩中仅检测到烷基单金刚烷系列,烷基双金刚烷系列不但不完整且丰度很低,这一现象表明原油的成熟度明显高于所研究烃源岩,这与生物标志化合物成熟度参数的结果相吻合。依据甲基单金刚烷指数MAI和甲基双金刚烷指数MDI与镜质体反射率间的对应关系,发现该凝析油对应的镜质体反射率RO值介于1.3%~1.6%之间,由此说明它源于盐城凹陷内处于凝析油气阶段的泰州组烃源岩。由此可见,金刚烷类化合物在确定原油和烃源岩中有机质成熟度上具有特殊意义。     

THE MIDDLE CAMBRIAN SUCCESSION IN THE CENTRAL BALTIC BASIN: GEOCHEMISTRY OF OILS AND SANDSTONE RESERVOIR CHARACTERISTICS

Some 36 oilfields, all producing from Middle Cambrian (Deimena Group) sandstones, are located in the central Baltic Basin in an area covering onshore Lithuania and Kaliningrad (Russia) and the adjacent offshore. This paper presents new data on the composition of crude oils from fields in this area and reviews the reservoir properties of the Deimena Group sandstones. Twenty‐one crude oil samples from fields in Lithuania and Kaliningrad were analysed by standard techniques including GC and GC‐MS. The oils had densities of 790.5 to 870.0 kg/m³, and had low asphaltene (<2.2%) and sulphur (<0.44%) contents. The gasoline fraction (b.p. >200°C) ranged from 12–34%. The saturated hydrocarbon content was 35.3 to 77.8%, and the ratio of saturate to aromatic hydrocarbons was 2.1–5.2, indicating long‐distance migration or high thermal maturities. GC analyses of saturate fractions indicated a composition dominated by n‐alkanes with a maximum at C₁₃–C₁₅ and reduced abundance in the C₂₀–C₃₅ range. The analysed crude oil samples are characterized by relatively low concentrations of steranes and triterpanes. Biomarker data indicated an algal origin for the precursor organic matter and a clastic‐dominated source rock. Sterane isomerization ratios imply that the oils are in general relatively mature. Exceptions are samples from the Juzno Olempijskoye and Deiminskoye fields, Kaliningrad, which were early mature. Oil from well Gondinga‐l (Lithuania) was lightly fractionally evaporated and has a relatively higher density, higher viscosity, higher asphaltene content and lower content of saturated fractions. Stable carbon isotope ratios of crude oils and saturated and aromatic fractions were analysed. Whole oils showed little carbon isotope variation, but there were significant differences in δ¹³C ratios for saturated and aromatic fractions. The geochemical data show differences in oil sourcing and indicate the possible existence of different kitchen areas in the Kaliningrad region. Vertical and lateral variations in Deimena Group reservoir properties are controlled by variations in quartz cementation. In fields in western Lithuania, sandstone porosity ranges from 0.7 to 20% and permeability from 20 mD to 300 mD; in fields onshore Kaliningrad, porosity is up to 34% and gas permeability up to 4.8 D. Wide variations in porosity and permeability occur at a field scale.     

东海盆地西湖凹陷天然气及原油地化特征分析

对西湖凹陷天然气组分、轻烃、碳同位素等特征进行了系统地分析,结果表明天然气类型以煤型气与油型气的混源气为主且偏煤型气,其演化成熟度较高,属于Ⅱ型偏煤型母质成熟—过熟阶段的产物,主要来源为平湖组及其下部的烃源岩。通过对原油的物性、饱和烃、碳同位素、轻烃等特征的研究表明,西湖凹陷原油可分为轻质原油与凝析油2种类型。这2种类型原油物性一致,母质来源均有煤的贡献,形成于弱还原的淡水湖沼环境;原油可以分为成熟(Ro1.0%)和高熟—过熟(Ro=1.3%~2.0%)2种类型。     

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。      

典型海相油和典型煤成油轻烃组成特征及地球化学意义

通过对塔里木盆地塔中隆起典型海相原油和吐哈盆地典型煤成油的轻烃组分、Mango参数和成熟度等分析后发现:2类原油轻烃组分含量差异明显，塔中隆起海相油富含正庚烷,吐哈盆地煤成油则富含甲基环己烷;塔中隆起海相油Mango参数K₁值分布在0.97~1.19之间，与Mango所报道的结果相一致，而吐哈盆地煤成油的K₁值却异常高（1.35~1.66）；塔中隆起海相油成熟度参数庚烷值(32.3%~45.4%)和异庚烷值(1.9~3.7)高于煤成油，已处于高成熟阶段，塔中隆起典型海相油的形成温度要明显高于吐哈盆地煤成油。     

东濮凹陷西斜坡地区原油成熟度

胡状集和庆祖集油田是东濮凹陷西斜坡地区的两个主要油田,原油主要分布在长垣断层与石家集断层之间二台阶构造带上,该区原油具有饱和烃含量低、含蜡量高、碳同位素较重的特征。利用GC-MS技术对原油分析结果显示,饱和烃馏分中Cg甾烷立体异构体比值、三降藿烷w(Ts)/w(Tm)比值普遍较低,这些参数值与我国不同盆地典型低熟原油分布范围十分相似。芳烃馏分中检出了反映低成熟阶段生物标志物一-烷基噻吩、四氢噻吩等含硫化合物及多羟基维生素E系列。综合分析认为,胡状集和庆祖集油田的原油为低成熟原油,而非成熟原油。     

孤南洼陷低熟油成因分析

济阳坳陷孤南洼陷低熟油的地质储量可达数千万吨，类似的由沙一段和沙四段烃源岩形成的低熟油在渤海湾盆地普遍可见。以孤南洼陷为例，讨论了低熟油勘探中的有关问题。明确提出判别低熟原油的指标是其Ｃ２９甾烷的异构化系数（其值０．３０～０．３５可作为上限值），ＯＥＰ及Ｐｒ／ｎＣ１７和Ｐｒ／ｎＣ１８可作为辅助指标。低熟原油可以是中等密度的高蜡油，其组分特征是高饱芳比和高非沥比。孤南洼陷生成低熟油的沙一段烃源岩为富含藻类有机质的油页岩，形成于半咸水—咸水、强还原的沉积环境。孤南洼陷低熟油形成阶段的Ｒｏ值上限为０．４０％～０．４５％，相应的深度为２３００～２５００ｍ；Ｒｏ值下限为０．６０％～０．６５％，相应的深度为３０００～３２００ｍ。咸水环境由富含藻类的有机质早期生烃，可能是最主要的低熟油形成机制。图２表４参８（邓春萍摘）     

冀中坳陷苏桥-文安油气田混源油定量识别模式研究(一):原油成因分类及地球化学特征

通过对原油的族组成、碳同位素、饱和烃和芳烃地球化学特征的剖析,查明苏桥-文安地区原油中不仅存在煤成油,而且存在由煤成油与下第三系原油混合而成的混源油。煤成油表现出饱和烃含量极其丰富、Pr/Ph值高(大于2)、三环萜烷以低碳数(C19～C21)化合物占优势并有递减变化趋势、C24四环萜烷丰富和伽马蜡烷含量低等地球化学特征。下第三系原油与煤成油的地球化学特征恰恰相反,Pr/Ph值低(小于1)、低碳数三环萜烷含量低并有递增变化趋势、C24四环萜烷的含量不高和伽马蜡烷含量相对丰富。混源油的地球化学特征介于煤成油与下第三系原油之间,但参数值受控于端元油混入的绝对含量。在以上地球化学特征基础上提出了冀中坳陷煤成油、下第三系油和混源油的识别指标。     

辽河盆地东部凹陷欧利坨子地区原油性质与成因

油—油精细对比揭示辽河盆地欧利坨子地区低熟油和成熟油共存,与东部凹陷其它地区原油相比总体上成熟度较低.表现在原油族组成中饱和烃和饱芳比值低(饱/芳值小于3.0)、生物标志物中反映成熟度的参数明显偏低、饱和烃和芳烃碳同位素值(分别为-26.00‰~-27.50‰和-25.00‰~-26.50‰)也明显低于东部凹陷其它地区,单体烃碳同位素类型曲线特征也揭示其原油成熟度较低.油—源对比揭示欧利坨子地区原油来自沙三中下段的暗色泥岩,生物标志物资料揭示源岩热演化程度明显低于东部凹陷其它地区,因而造成该区原油成熟度较低.      

IN‐RESERVOIR FRACTIONATION AND THE ACCUMULATION OF OIL AND CONDENSATES IN THE SURMA BASIN,NE BANGLADESH

Petroleum in the Surma basin, NE Bangladesh (part of the Bengal Basin) ranges from waxy crude oils to condensates. The origin and source rocks of these hydrocarbons were investigated based on the distributions of saturated and aromatic hydrocarbons in 20 oil samples from seven oil and gas fields. The relative compositions of pristane, phytane and adjacent n‐alkanes suggest that the source rock was deposited in a non‐marine setting. The abundance and similar distribution of biphenyls, cadalene and bicadinanes in most of the crude oils and condensates indicates a significant supply of higher‐plant derived organic matter to the source rocks. Maturity levels of the crude oils and condensates from the Surma basin correspond to calculated vitrinite reflectance (R_c) values of 1.0–1.3%, indicating hydrocarbon expulsion from the source rock at a comparatively high maturity level. The R_c values of oils from the Titas field in the southern margin of the Surma basin are relatively low (0.8–1.0%). Some oils were severely biodegraded. The similar distribution of diamondoid hydrocarbons in both biodegraded and non‐biodegraded oils indicated similar types of source rocks and similar maturity levels to those of oils from the Surma basin. The Oligocene Jenam Shale and/or underlying non‐marine deposits located at greater depths may be potential source rocks. The diversity of the petroleum in the Surma basin was likely due to evaporative fractionation, resulting in residual waxy oils and lighter condensates which subsequently underwent tertiary migration and re‐accumulation. Evaporative fractionation due to modification of the reservoir structure occurred during and after the Pliocene, when large‐scale tectonic deformation occurred in and around the Bengal Basin.     

Organic geochemistry investigations of crude oils from Bayoot oilfield in the Masila Basin,east Yemen and their implication for origin of organic matter and source-related type

Thirteen crude oil samples from fractured basement reservoir rocks in the Bayoot oilfield, Masila Basin were studied to describe oil characteristics and to provide information on the source of organic matter input and the genetic link between oils and their potential source rock in the basin. The bulk geochemical results of whole oil and gasoline hydrocarbons indicate that the Bayoot oils are normal crude oil, with high hydrocarbons of more than 60%. The hydrocarbons are dominated by normal, branched and cyclic alkanes a substantial of the light aromatic compounds, suggesting aliphatic oil-prone kerogen. The high abundant of normal, branched and cyclic alkanes also indicate that the Bayoot oils are not biodegradation oils.The biomarker distributions of isoprenoid, hopane, aromatic and sterane and their cross and triangular plots suggest that the Bayoot oils are grouped into one genetic family and were generated from marine clay-rich source rock that received mixed organic matter and deposited under suboxic conditions. The biomarker distributions of the Bayoot oils are consistent with those of the Late Jurassic Madbi source rock in the basin. Biomarker maturity and oil compositions data also indicate that the Bayoot oils were generated from mature source rock with peak oil-window maturity.