塔中地区奥陶系储层烃包裹体特征及成藏分析

利用新发明的不同期次烃包裹体组份提取仪器"多功能烃包裹体取样机",分别提取了塔中地区5期烃包裹体组份,并成功地分析出组份生物标志化合物,论证了5期烃包裹体油气的来源:第Ⅰ期烃包裹体来源于满加尔坳陷的寒武系海相碳酸盐岩烃源岩、第Ⅱ期烃包裹体来源于满加尔凹陷的中奥陶系烃源岩、第Ⅲ期烃包裹体来源于塔中下部寒武系海相碳酸盐岩烃源岩、第Ⅳ期烃包裹体是由寒武系海相碳酸盐岩原油分解而成、第Ⅴ期烃包裹体来源于塔中上奥陶统良里塔格组烃源岩。其形成时间分别为:早海西期约383Ma、晚海西期约240~260Ma、燕山-早喜山期早期、23Ma喜山运动二幕、喜山运动晚期到现在。塔中奥陶系储层中不是每一个圈闭都含有以上5期烃包裹体,有的圈闭只含其中的一期或二期或三期。第Ⅰ期主要是油气运移的 "足迹",仅路过奥陶系,未成藏。第II、IV、V期成藏普遍影响塔中奥陶系,是油气成藏的"历史",使奥陶系的原油具有中奥陶统油源(第II期)、上奥陶统油源(第V期)和寒武系油源(第IV期)混源特征,第Ⅱ、Ⅳ期烃包裹体大量存在是塔中Ⅰ号坡折带凝析油气高产的"标志"。 第Ⅲ期包裹体的发育可能预示在塔中东部地区中下奥陶统及寒武系形成大油藏,塔中东部地区是找原生大型油藏的重要靶区。     

利用石油包裹体烃组分信息恢复塔中地区油气成藏过程

为恢复塔中地区油气成藏过程,利用改进的石油包裹体烃组分分析方法进行了详细的研究。结果表明塔中地区储层油和包裹体油的组分差异明显。包裹体油和下奥陶统储层油中伽马蜡烷和C28甾烷相对丰度较高,来源于寒武系-下奥陶统烃源岩,其他储层油中伽马蜡烷和C28甾烷相对丰度较低,来源于中-上奥陶统烃源岩。储层油的成熟度高于对应层位的包裹体油,表明高成熟度的石油再次充注。石炭系和志留系包裹体油和储层油中存在25-降藿烷系列,表明石油成藏后遭受了生物降解作用。恢复了塔中地区3期油气成藏过程,第1期和第2期分别为志留纪末期和二叠纪末期来源于寒武系-下奥陶统烃源岩的油气成藏,第3期为二叠纪末期来源于中-上奥陶统烃源岩的油气成藏。     

塔里木盆地海相油气源与混源成藏模式

塔里木盆地油气源长期争论不休.采用单体烃同位素、包裹体成分与年代指示生物标志物等途径, 对塔里木盆地塔中、轮南典型油气藏进行了油气成因与混源成藏模式的研究.结果表明, 塔中、轮南绝大部分原油生物标志物与中上奥陶统烃源岩相似, 仅少部分原油显现与寒武系—下奥陶统烃源岩相近的特征, 但正构烷烃单体烃碳同位素分析表明, 原油绝大部分实质仍为混源油.塔中包裹烃成分分析进一步证实了原油的混源特性.利用同位素进行的混源定量结果表明, 塔中原油中寒武系—下奥陶统成因原油的混入量约为11%~100%(均值45%); 轮南地区约为11%~70%(均值36%), 表明寒武系—下奥陶统、中上奥陶统均为塔里木盆地的主力烃源岩.油气运移地化指标与地质条件的综合研究认为, 塔中地区断层是油气运移的重要通道, 塔中I号断层与斜交的走滑断层的交汇点是油气的主要注入点; 轮南地区侧向运移特征较明显.研究区存在调整型、多期充注型与原生型多种混源成藏模式.塔里木海相油气的普遍混源表明深层仍有油气勘探潜能.揭示海相混源油气成藏机制是指导塔里木海相油气勘探的关键.      

中国海相油气田勘探实例之十二 塔里木盆地轮南奥陶系油气田的勘探与发现

轮南奥陶系海相碳酸盐岩油气田位于塔北隆起轮南低凸起中部,是中国第一个海相碳酸盐岩特大型油气田。油气田发现于1988年,至2008年底控制+探明油气地质储量为18.78×108t。塔里木盆地长期构造沉积演化形成了轮南奥陶系碳酸盐岩大型古潜山及内幕背斜,潜山背斜具有古隆起控油,岩溶斜坡油气富集及准层状油气藏等特征。油气田区域性盖层为中—上奥陶统、下石炭统、上三叠统泥岩,主力烃源岩为寒武系—下奥陶统与中—上奥陶统碳酸盐岩及泥灰岩,主要目的层为奥陶系石灰岩顶面之下200m范围内的潜山岩溶缝洞型储集体与内幕层间岩溶缝洞型储集体。通过缝洞系统预测评价、酸压储层改造、稠油掺稀开采等技术攻关,勘探开发一体化管理,创新了复杂碳酸盐岩勘探开发理论与配套技术,实现了轮南奥陶系油气产量储量的快速增长。论述油气田勘探与发现的历程,剖析了取得勘探突破的实践与认识。     

塔中隆起原油特征与成因类型

塔里木盆地塔中隆起油气性质多样、分布与成因复杂, 为揭示油气的特征与成因, 对塔中及外围104个原油样品进行了精细地球化学研究.依据单体烃碳同位素、特征生物标志物分析, 将塔中原油分为4种类型: (1) 寒武系成因原油, 具有较重正构烷烃单体烃碳同位素(-29.6‰~-29.1‰)、甲藻甾烷较发育及C₂₇、C₂₈、C₂₉规则甾烷呈反“L”型或线型分布等特征; (2) 中、上奥陶统成因原油, 具有较轻的正构烷烃单体烃同位素(-34‰~-35.6‰)、甲藻甾烷等不太发育与C₂₇、C₂₈、C₂₉规则甾烷呈“V”型分布等特征; (3) 富含含硫芳烃-二苯并噻吩原油, 主要分布于塔中4井区; (4) 混源油, 单体烃碳同位素特征界于Ⅰ、Ⅱ类原油之间, 是塔中最为主要的原油类型.油-油对比与油气性质分析表明, 塔中地区至少有两套主力烃源岩供烃.塔中部分原油生物标志物显示寒武系-下奥陶统成因特征, 而单体烃碳同位素却与中上奥陶统成因原油更为接近, 这种不同馏分的不一致现象系不同成因原油混源的结果, 反映单一应用生物标志物指标有其局限性.塔中油气性质具有分带、分块、分层特征, 反映叠合盆地多源、多期成藏、储层非均质性等多种特性.      

塔里木盆地原油轻烃单体烃碳同位素组成特征

为探讨塔里木盆地原油类型和油源问题,运用色谱-同位素质谱分析技术,分析了该盆地塔中、塔北、塔东与库车地区的典型原油轻烃单体烃碳同位素组成。结果表明,不同结构轻烃化合物中,支链烷烃与环己烷系列比环戊烷系列更具明显的成因判识意义。2-甲基环戊烷2 mC_5、3-甲基环戊烷3 mC_5、3-甲基环己烷3 mC_6、环己烷CYC6与甲基环己烷mCYC_6等化合物的δ~(13)C在煤成油最高,δ~(13)C大于-21‰;湖相油次之,δ~(13)C位于-25‰~-22‰之间;再次之为寒武系-下奥陶统海相原油,δ~(13)C位于-27‰~-21‰之间,最轻的为上奥陶统海相原油,δ~(13)C小于-28‰。其碳同位素值可以较好的判别该盆地寒武系-下奥陶统海相油、上奥陶统海相油、湖相油与煤成油。优选的8个特征化合物碳同位素可以作为原油成因类型的划分标志,尤其是2-甲基环戊烷2 mC_5、3-甲基环戊烷3 mC_5、3-甲基环己烷3 mC_6、环己烷CYC6与甲基环己烷mCYC_6等化合物。特征轻烃化合物的碳同位素组成可成为不同成因原油的划分标志。     

塔里木盆地塔中隆起志留系油气成藏及分布特点

塔里木盆地塔中隆起志留系油气成藏具有两源三期的成藏特点,"两源"是指油气来源于寒武系、中、上奥陶统两套烃源岩;"三期"是指从沥青到可动油的形成经历了加里东晚期、海西晚期、燕山—喜山期三个成藏期,沥青的形成是早期油气运移聚集过程中遭破坏的结果,目前所发现的可动油是以中、上奥陶统油气源为主的晚期成藏的结果。发育三种油气藏类型,即背斜构造、地层岩性以及火山岩遮挡型。塔中隆起志留系油气聚集受三大因素控制,一是隆起构造背景,围绕古隆起构成多种圈闭类型组合的复合油气聚集区;二是有效盖层,志留系中的油气显示十分活跃,包括沥青、稠油和正常油,沥青和稠油分布在红色泥岩段以下,而可动油集中分布在灰色泥岩段之下;三是优质储层,砂岩储层分布广泛,储层储集空间有次生-原生孔隙型、原生-次生孔隙型、微孔隙型三种类型,孔隙度3.3 %～17.4 %,渗透率(0.1 ～667.97)×10-3μm2。     

塔里木盆地塔北地区具有寒武系特征原油的分布及其成因

塔里木盆地塔北地区油气资源十分丰富,油气成因复杂。海相原油主要来自于寒武系或奥陶系烃源岩,或者二者混源。其中,对混源油定性研究多、定量研究少。随着勘探的深入和精细,需要定量回答油气的混源比例。本文根据不同端元油的人工混源配比实验,发现生物标志化合物具有随混源比例变化的特征,建立了混源比例与生标参数之间的关系式,并对塔北地区混源油中寒武系原油比例做了定量计算,进而研究了其分布规律与成因机制。研究认为,塔北地区原油主要来自于中、上奥陶统烃源岩,寒武系烃源岩有少量贡献。从空间分布上来看,具有从西到东、从浅至深,混源油中寒武系烃源岩来源的原油比例具有逐渐增高的特点,高比例寒武系来源原油的混源油主要分布在轮南低凸起的桑塔木断垒带东侧和轮东断裂周围,明显受烃源岩分布、输导体系和成藏过程等因素控制,该研究对进一步认识塔北地区油气生成、运移、聚集规律,以及指导油气勘探都具有重要意义。     

塔里木盆地原油中二苯并噻吩的分布及主力油源岩类型判识

在塔北隆起大部分地区和塔中隆起发现的工业油气流具有与海相下古生界（奥陶系）油源岩相同的地球化学特征，且含有十分丰富的二苯并噻吩类有机硫化物。本文详细研究了世界各地若干典型海相碳酸盐岩和泥页岩来源油中二苯并噻吩（ＤＢＴｓ）的分布。发现新参数二苯并噻吩脱甲基指数（ＤＤＩ）和甲基重排指数（ＤＭＩ）受成熟度影响小，能有效地区分油源岩岩性。根据ＤＢＴｓ的相对含量和ＤＤＩ及ＤＭＩ指标判识，表明塔里木盆地下古生界原油主要来自碳酸盐岩，奥陶系广海陆棚台地相喑色泥晶灰岩是主力油源岩。这一认识将有助于确认主力油源区的分布，具有较大的勘探意义。     

塔里木盆地原油噻吩类化合物的组成特征及地球化学意义

对塔里木盆地典型原油噻吩类化合物含量和组成特征研究,发现不同类型原油苯并萘噻吩和二苯并噻吩系列化合物占芳烃化合物的百分含量相差明显,海相油含量最高,湖相油次之,而煤成油最低。本文提出了４－甲基二苯并噻吩／二苯并噻吩、（２＋３）－甲基二苯并噻吩／二苯并噻吩比值是区分海相油和湖相油新的有机地球化学参数。二苯并噻吩系列化合物最大烷化度表明海相油呈现出高烷化度,而陆相油则表现为低烷化度,即从海相泥灰岩原油、海相碳酸盐岩原油到湖相油和煤成油依次减少。这是因为富硫与贫硫干酪根在生烃过程中的环化作用或支链化作用程度差异所造成的。     

Correlation of crude oils and oil components from reservoirs and source rocks using carbon isotopic compositions of individual n-alkanes in the Tazhong and Tabei Uplift of the Tarim Basin,China

Carbon isotopic compositions were determined by GC–IRMS for individual n-alkanes in crude oils and the free, adsorbed and inclusion oils recovered by sequential extraction from reservoir rocks in the Tazhong Uplift and Tahe oilfield in the Tabei Uplift of Tarim Basin as well as extracts of the Cambrian–Ordovician source rocks in the basin. The variations of the δ¹³C values of individual n-alkanes among the 15 oils from the Tazhong Uplift and among the 15 oils from the Triassic and Carboniferous sandstone reservoirs and the 21 oils from the Ordovician carbonate reservoirs in the Tahe oilfield demonstrate that these marine oils are derived from two end member source rocks. The major proportion of these marine oils is derived from the type A source rocks with low δ¹³C values while a minor proportion is derived from the type B source rocks with high δ¹³C values. Type A source rocks are within either the Cambrian–Lower Ordovician or the Middle–Upper Ordovician strata (not drilled so far) while type B source rocks are within the Cambrian–Lower Ordovician strata, as found in boreholes TD2 and Fang 1. In addition, the three oils from the Cretaceous sandstone reservoirs in the Tahe oilfield with exceptionally high Pr/Ph ratio and δ¹³C values of individual n-alkanes are derived, or mainly derived, from the Triassic–Jurassic terrigenous source rocks located in Quka Depression.The difference of the δ¹³C values of individual n-alkanes among the free, adsorbed and inclusion oils in the reservoir rocks and corresponding crude oils reflects source variation during the reservoir filling process. In general, the initial oil charge is derived from the type B source rocks with high δ¹³C values while the later oil charge is derived from the type A source rocks with low δ¹³C values.The δ¹³C values of individual n-alkanes do not simply correlate with the biomarker parameters for the marine oils in the Tazhong Uplift and Tahe oilfield, suggesting that molecular parameters alone are not adequate for reliable oil-source correlation for high maturity oils with complex mixing.     

塔中隆起海相碳酸盐岩大型凝析气田成藏特征与勘探

多次资评与勘探实践表明塔中隆起成藏条件优越,海相碳酸盐岩油气资源丰富,奥陶系油气藏集中赋存于上奥陶统礁滩体与下奥陶统风化壳储层中,缝洞系统控制了大型凝析气藏纵向多套叠置-横向准层状分布规律。多学科、动静态一体化研究表明,形成塔中海相碳酸盐岩大型凝析气田主力烃源岩为寒武-奥陶系两套碳酸盐岩,原油具有明显的混源特征,天然气主要来源于中-下寒武统高成熟度原油裂解气。奥陶系海相碳酸盐岩凝析气藏是古油藏在喜山期被寒武系来源的原油裂解气气侵的结果,经历了三期成藏过程,即中晚加里东期、晚海西期原油充注,喜山期注气。两套烃源岩长期供烃是形成塔中奥陶系海相碳酸盐岩大型凝析气田的物质基础,构造作用、岩溶作用是形成了塔中奥陶系多套优质碳酸盐岩储集体的主控因素,断裂、不整合面、缝洞发育带构建的网状油气输导体系是塔中海相碳酸盐岩复式聚集混源成藏的重要保障。塔中奥陶系海相碳酸盐岩具备10亿吨当量的油气资源潜力。     

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.     

The Formation and Distribution of the Marine Hydrocarbon Source Rock in the Tarim Basin, NW China

There are significant differences in type and distribution between marine source rock and continental source rock. According to the iithology, the Cambrian-Ordovician source rock in the Tarim basin is divided into two types： the carbonate source rock and the mud source rock. The two sets of source rocks are developed mainly in three sets of formations, Lower-Middle Cambrian carbonate source rock and mud source rock, Lower-Middle Ordovician mud source rock and Upper Ordovician lime mud source rock. The stratigraphic and areal distributions of the source rocks are controlled by the altitude and the sedimentary facies respectively. The mud source rock is developed in slope-semi deep sea environment. The source rock developed in the slope sedimentary environment is related with the anoxic environment and the one developed in semi deep sea has a close relationship with the up-flowing sea water. The carbonate source rock is developed mainly in platform slope of highstand systems tract and it is usually intimately associated with the salt rock. The Lower-Middle Cambrian carbonate source rock is developed mainly in the Bachu, Tazhong, Tangguzibasi and Yingmaili areas. The Lower-Middle Cambrian mud source rock is mainly developed in the areas east of the line of Kunan 1-Tadong 1. The Lower-Middle Ordovician mud source rock is developed mainly in the east slope of the Manjiaer depression. The carbonate source rock of Early Ordovician is developed mainly in the platform slope of highstand systems tract, such as the south margin of Tabei, the north slope of Tazhong, the Bachu area and Keping area.     

Distribution and Significance of Carbazole Compounds in Palaeozoic Oils from the Tazhong Uplift, Tarim

Carbazole compounds in crude oils from the Tazhong uplift of the Tarim basin have been fractionated and detected and successfully used to study petroleum migration and trace source rocks in the study area. Alkylcarbazoles have been found in large amounts in the oil samples analyzed and alkylbenzocarbazoles detected in a small concentration only in part of the samples, but alkyldibenzocarbazoles have not been found in oils. Based on the distribution of G1, G2 and G3 of C2-alkylcarbazoles, the ratio of C3-carbazoles to C2-carbazoles and the relative amounts of alkylcarbazoles and alkylbenzocarbazoles, one can know that the vertical oil migration in the Tazhong uplift is generally from below upward, i.e. from the Ordovician through the Silurian to the Carboniferous. Evidently, source rocks in the uplift should be lower Palaeozoic strata (Ordovician and Cambrian). This study shows that carbazoles are of great importance in the study of petroleum migration and source rocks.     

塔中奥陶系原油的地球化学特征及其来源

塔中奥陶系的油气资源十分丰富,是塔里木盆地油气勘探的重点层系之一,但油源仍是困扰地质勘探家的重要问题。通过系统分析塔中奥陶系原油的地球化学特征,进行了原油族群划分和油源判识。原油以轻质油为主,轻烃分析表明,原油没有发生大量裂解,原油的生成温度介于115～129℃,表明其主体成分形成于生油窗阶段。运用特征性生物标志物系统分析表明,原油可分为三个族群,分别来源于中—上奥陶统源岩、寒武系源岩及混合来源。在“三芴”组成上,原油均以较低的氧芴含量和较高的硫芴含量为特征。原油中饱和烃的碳同位素比值均轻于-31.2‰,平均值为-32.8‰,芳烃的碳同位素比值均轻于-30.4‰,平均值为-31.7‰,这些特征明显与塔东2井和塔深1井的寒武系原油不同。分析认为,碳同位素明显偏重的原油应来源于寒武系源岩,但碳同位素较轻的原油可能来源于中—上奥陶统源岩,也可能来源于寒武系源岩。     

塔里木盆地塔中、塔北地区志留系古油藏的油气运移

运用含氮化合物咔唑类探讨塔中、塔北地区在第一期成藏时志留系油气藏的烃类的运移方向, 为建立古油藏成藏模式, 预测原生油气藏分布提供依据.研究表明, 塔中志留系古油藏的油气主要来源于满加尔凹陷的中、下寒武统烃源岩, 向西南—南的方向首先进入塔中志留系, 然后沿不整合面或顺储层从北西向南东和从北东向南西2个方向向志留系在塔中地区的尖灭线附近运移.塔北志留系古油藏的油气也主要来自满加尔凹陷的中、下寒武统烃源岩, 首先向北西方向进入塔北隆起的志留系, 然后在志留系储层内或不整合面沿上倾方向继续向北西方向运移进入圈闭.      

Accumulation and Reformation of Silurian Reservoir in the Northern Tarim Basin

Silurian sandstone in Tarim Basin has good reservoir properties and active oil and gas shows, especially thick widely-distributed bituminous sandstone. Currently, the Silurian was found containing both bitumen and conventional reservoirs, with petroleum originating from terrestrial and marine source rocks. The diversity of their distribution was the result of "three sources, three stages" accumulation and adjustment processes. "Three sources" refers to two sets of marine rocks in Cambrian and Middle-Upper Ordovician, and a set of terrestrial rock formed in Triassic in the Kuqa depression. "Three stages" represents three stages of accumulation, adjustment and reformation occurring in Late Caledonian, Late Hercynian and Late Himalayan, respectively. The study suggests that the Silurian bitumen is remnants of oil generated from Cambrian and Ordovician source rocks and accumulated in the sandstone reservoir during Late Caledonian-Early Hercynian and Late Hercynian stages, and then damaged by the subsequent two stages of tectonic uplift movements in Early Hercynian and Pre-Triassic. The authors presumed that the primary paleo-reservoirs formed during these two stages might be preserved in the Silurian in the southern deep part of the Tabei area. Except for the Yingmaili area where the Triassic terrestrial oil was from the Kuqa Depression during Late Himalayan Stage, all movable oil reservoirs originated from marine sources. They were secondary accumulations from underlying Ordovician after structure reverse during the Yanshan-Himalayan stage. Oil/gas shows mixed-source characteristics, and was mainly from Middle-Upper Ordovician. The complexity and diversity of the Silurian marine primary properties were just defined by these three stages of oil-gas charging and tectonic movements in the Tabei area.     

塔里木盆地原油的成因研究

对塔里木盆地原油和生油岩饱和烃进行ＧＣ－Ｃ－ＭＳ和ＧＣ－ＭＳ分析，利用单个正构烷烃碳同位素组成和三环萜烷分布特征进行油源对比，研究了塔里木盆地原油的油源问题；根据寒武—奥陶系富含菌藻有机质生油岩饱和烃色谱分析结果，对塔里木盆地海相原油含蜡较高的成因进行了探讨