库车前陆坳陷形成大气区的烃源岩条件

随着勘探的深入,库车前陆坳陷逐渐成为我国重要的大气区.本文对其形成大气区的关键条件之一的烃源岩特征进行了深入研究.库车坳陷主要分布中-上三叠统浅湖-半深湖相泥质烃源岩和中-下侏罗统煤系烃源岩,具有厚度大、丰度高、类型差和成熟度高的特点.三叠-侏罗系烃源岩具有十分丰富的天然气生成量,天然气来源不是制约库车坳陷天然气勘探的因素;根据三叠-侏罗系烃源岩的类型特征和成熟度特征认为库车坳陷资源丰富、以气为主,在天然气的生成上侏罗系烃源岩的贡献要大于三叠系.     

库车南斜坡中—新生界油气运移地球化学示踪

库车南部斜坡中—新生界属于库车陆相油气系统,油气主要来源于库车坳陷的三叠系和侏罗系烃源岩。本文利用色谱、色谱- 质谱及碳同位素分析手段, 对库车南部斜坡带已发现的白垩系和古近系油气地球化学组成特征进行了详细研究,在明确油气来源基础上,根据典型油气藏解剖,分析油气运移输导路径,优选油气地球化学运移参数示踪油气运移充注路径。研究表明：库车南斜坡中—新生界原油呈现低密度、低黏度、低凝固点、低含硫及高含蜡的陆相原油特征。原油总体以藻类和水生浮游生物母源为主,反映生烃母质弱还原- 弱氧化的沉积环境,体现混合型干酪根母源特征,其中白垩系原油母源以湖相水生生物为主,主要来自三叠系湖相烃源岩;古近系原油除了三叠系湖相烃源岩的贡献外,伴随有以陆生高等植物输入为主的侏罗系煤系烃源岩。天然气具有中等甲烷含量、重烃含量高、氮气含量高和无硫化氢的特点,白垩系天然气主要是三叠系湖相原油伴生油型气;古近系天然气主体属于煤成气,主要来源于中下侏罗统煤系烃源岩,部分混有早期三叠系湖相烃源岩的原油伴生油型气。区内中—新生界发育由砂体、不整合、断裂构成的复杂油气输导体系,三叠系烃源岩生成的大量原油主要是沿白垩系底部不整合或下伏连接砂体运移到白垩系下部的圈闭中,侏罗系烃源岩生成天然气主要是沿古近系底部不整合面及下伏巨厚砂体运移到古近系底砂岩段圈闭中。综合油气藿烷参数Tm/(Ts+Tm)、重排藿烷参数C30DH/C30H、甲基二苯并噻吩(MDBT)参数4- /1- 甲基二苯并噻吩、C1/C2值、iC4/nC4值、天然气烷烃碳同位素组成,认为库车南部斜坡带存在却勒到玉东构造带由北向南和英买力、红旗构造带由北东向南西方向的2个主运移充注路径和却勒到羊塔克构造带由西向东的1个次级充注运移路径,下一步油气勘探应针对不同的油气运移路径方向,优先选择主运移通道上的岩性尖灭砂体实施部署。     

煤型气中丁烷的地球化学特征及意义——以塔里木盆地库车坳陷为例

为研究母质类型、热演化程度和运移方向等对煤型气中丁烷地球化学特征的影响,统计分析了塔里木盆地库车坳陷天然气中丁烷组分和碳同位素的变化特征。结果表明,母质类型、烃源岩热演化程度及成藏过程、天然气成熟度共同控制了库车坳陷煤型气i C4/n C4值;库车坳陷煤型气正、异丁烷的碳同位素比值与δ13C1均具有明显的正相关性,即随着天然气成熟度增加,正、异丁烷均变重,且异丁烷相对更富集重碳同位素;在砂岩疏导层中,煤型气i C4/n C4值沿天然气渗滤运移方向有减小的趋势,大北气田天然气总体上来讲由南向北运移。天然气中的丁烷组分和碳同位素特征研究具有重要的理论意义,与甲烷、乙烷等常规研究组分类似,丁烷组分和同位素特征也可成为天然气成熟度的替代指标。     

库车坳陷东部吐格尔明地区天然气地球化学特征及油气充注史

库车坳陷东部油气地质条件复杂,天然气成因与油气充注时间存在争议,油气充注史不明,制约其油气勘探进程。利用天然气组分、碳同位素组成、流体包裹体岩相学与均一温度等分析测试数据,结合沉积埋藏史及构造演化史,研究了库车坳陷东部吐格尔明地区天然气地球化学特征、天然气成因类型及油气充注时间,分析了油气充注成藏过程。结果表明:吐格尔明地区天然气组分以甲烷为主,甲烷含量为75.56%~90.11%,干燥系数为0.79~0.93;δ¹³C₁和δ¹³C₂值为-35.73‰~-33.80‰和-26.41‰~-25.30‰,天然气成因类型属于成熟阶段的煤成气。吐格尔明地区侏罗系砂岩储层发育两类流体包裹体,分别为黄色液态烃包裹体和蓝白色荧光的气液烃包裹体、灰色的气烃包裹体,表明该区存在两期油气充注,第一期为13~7 Ma的原油充注,第二期为2.6 Ma以来的天然气充注。康村组早中期,吐格尔明地区烃源岩形成的原油充注至宽缓背斜圈闭中保存;库车组晚期,侏罗系克孜勒努尔组与阳霞组发育良好的源储组合,天然气近距离充注成藏。     

塔里木盆地库车坳陷中生界烃源岩生烃动力学参数研究

根据封闭体系黄金管热模拟实验结果,应用Kinetics专用软件,研究了塔里木盆地库车坳陷中生界不同类型烃源岩的生烃特征与动力学参数。库车坳陷侏罗系煤、碳质泥岩、泥岩及三叠系湖相泥岩具有各自的活化能分布和频率因子,揭示出其生烃行为的差异性。利用GOR-IsotopeKinetics软件,推导了库车坳陷侏罗系煤、泥岩和三叠系湖相泥岩3类烃源岩的碳同位素动力学参数。上述参数的获取,为盆地模拟、烃源岩评价、生烃量计算及资源量预测提供了重要的基础地球化学数据。      

库车坳陷克拉苏冲断带轻质原油地球化学特征及成因

库车坳陷克拉苏冲断带以产气为主,并伴生一定量的轻质油。基于库车坳陷克拉苏冲断带18个轻质原油样品有机地球化学分析,总结了轻质原油生物标志化合物特征,对轻质原油进行了成因分类,并确定了其母质来源。研究结果表明,克拉苏冲断带克拉、大宛和大北地区轻质原油具有低Pr/Ph比值、高伽马蜡烷含量的特征,具有明显的湖相烃源岩特征。克拉地区原油母质以藻类输入为主,沉积于还原咸化环境。大宛和大北地区原油母质以高等植物输入为主,沉积于弱还原咸化环境。在克拉和大北地区部分原油母质还存在混合来源特征。按照生物标志化合物特征可以将库车坳陷克拉苏冲断带轻质原油划分为3种类型:第一类原油主要分布在大宛和大北地区,推测主要来源于中侏罗统恰克马克组下段湖相泥岩;第2类原油分布在克拉地区,推测主要来源于三叠系湖相烃源岩;第3类原油分布在克拉和大北地区,推测主要来源于三叠系湖相烃源岩,但侏罗系煤系烃源岩也具有一定贡献。     

塔里木盆地北部志留系顶面不整合中陆相原油的成藏历史与油气富集机制

塔里木盆地志留系发育厚层沥青砂,显示优越的含油气性.继塔中地区志留系原油勘探取得突破之后,塔北地区志留系砂岩风化壳型储层也发现了工业油藏.根据原油的甾、萜烷和噻吩类生物标记化合物的分布特征,结合原油的物理化学性质以及族组分稳定碳同位素特征分析,明确了塔北西部英买35井区志留系风化壳原油来源于库车凹陷三叠系黄山街组湖相烃源岩,与塔北东部同发育在志留系风化壳剥蚀尖灭线附近的哈得18C井海相原油形成鲜明对比.通过志留系砂岩流体包裹体均一温度测试,结合地层埋藏史研究成果,推断英买35井区志留系砂岩主要成藏时间为距今5 ～ 8Ma的晚喜山期.结合库车凹陷两套陆相烃源岩的生烃演化重构了该区域湖相原油的成藏过程,表明康村组沉积后白垩系卡普沙良群与志留系风化壳是湖相油气向台盆区输导的重要通道,预示着湖相原油运移充注的范围十分广泛.成藏机理分析表明,志留系风化壳的构造幅度和面积控制了油气的充注范围,直接盖层的封盖条件控制了风化壳储层的含油气性.塔北地区东、西部志留系风化壳的暴露时间和地层组合关系的差异,是东部形成海相含油气系统,而西部发育海、陆相油藏垂向上叠置,互不交叉的复式含油气系统的重要原因.     

库车前陆盆地天然气成藏过程及聚集特征

天然气的组分和碳同位素主要受母质类型和成熟度双重因素的控制,这是我们研究天然气的基础。但是越来越多的证据显示成藏过程对天然气组分和碳同位素也具有明显的控制作用。尽管库车前陆盆地不同构造单元的天然气来源一致,即主要来源于侏罗系烃源岩、其次为三叠系烃源岩,但是库车前陆盆地冲断构造带、斜坡区和前缘隆起区在天然气组分、干湿程度和碳同位素组成上具有明显的差异。库车前陆盆地经历了早期油气的聚集、破坏和晚期天然气聚集、调整的过程,研究认为成藏过程对库车前陆盆地不同构造单元的天然气组分和碳同位素特征具有明显的控制作用。     

塔里木盆地迪那2大型凝析气田的地质特征及其成藏机制

塔里木盆地库车坳陷迪那2凝析气田是中国目前发现的储量规模最大的凝析气田,含气层位为古近系苏维依组与库姆格列木群;储集岩以粉砂岩、细砂岩为主,属于低孔低渗储层,近似于致密砂岩气.气藏储量丰度大于15亿方/km2,气油比为8100～12948m3/m3,凝析油含量60～80g/m3;储层温度129 ～ 138℃,地温梯度为2.224℃/1OOm;地层压力为105 ～106MPa,压力梯度为0.39MPa/1OOm,压力系数为2.06～2.29,属于常温超高压凝析气藏.天然气以湿气为主,碳同位素较重,属于典型的煤成气;原油碳同位素较重,生物标志化合物体显出陆相油特征.研究认为,油气主要来自阳霞凹陷侏罗系煤系烃源岩;圈闭形成时间较晚,根据热史、埋藏史、烃源岩热演化史、流体包裹体等资料以及天然气碳同位素动力学拟合的油气充注成藏时间都表明,迪那2凝析气田的成藏时间是在2.5Ma以来,是一个典型的晚期快速充注成藏的大型凝析气田.晚期前陆逆冲挤压作用在形成超压的同时,发生了储层的致密化和烃类的充注,储层致密化过程与烃类充注同步.     

鄂尔多斯盆地天环坳陷南段侏罗系原油油源分析

天环坳陷南段位于鄂尔多斯盆地西南部,跨西缘冲断带和天环坳陷两个构造单元,地质条件复杂。近年来针对该区侏罗系低幅度构造岩性油藏的勘探取得了重大突破,钻遇多口工业高产油流,但目前对侏罗系油气的来源问题仍存在不同的认识,制约了勘探的进一步深入。应用色谱/质谱和碳同位素等分析方法和手段,对侏罗系原油与三叠系延长组长4+5段、长6段和长7段3套烃源岩从生物标志化合物、碳同位素等方面进行对比研究,并结合侏罗系油气成藏特征,探讨了侏罗系原油的油源。结果表明:天环坳陷南段侏罗系原油和长6段、长7段烃源岩在母源性质、沉积环境、成熟度等方面具有相近似的特征,二者具有较好的亲缘关系;区域性不整合面、裂缝成为沟通侏罗系储层与长6段、长7段油源的运移通道;侏罗系原油主要来源于长6段和长7段烃源岩。     

东海陆架盆地丽水西凹陷油气地球化学特征及其成因和来源

东海陆架盆地西部丽水西凹陷油气成因和来源争议较大。根据钻井地球化学分析测试结果、地震勘探资料,运用天然气地球化学、油气成藏过程研究思路,重新认识丽水西凹陷L36气田油气成因和来源,提出下一步油气勘探方向。L36气田天然气组分、干燥系数分析表明,天然气为“凝析油-湿气带”演化阶段产物,天然气成熟度R_o不小于1.1%。通过天然气碳同位素组成与中国近海典型油型气碳同位素特征的对比分析,认为L36气田天然气为油型气,估算天然气成熟度R_o在1.12%~1.14%之间,天然气来源于丽水西凹陷下古新统月桂峰组湖相烃源岩。L36气田产出的凝析油C₇轻烃具有甲基环己烷含量占优特征,与湖相烃源岩来源的凝析油C₇轻烃组成特征存在显著差异;中古新统灵峰组浅海相烃源岩具有甾烷C₂₇20R/C₂₉20R小于1、不含C₃₀4-甲基甾烷、伽马蜡烷含量低的特征,指示L36气田凝析油来源于下古新统灵峰组浅海相烃源岩,证实了丽水西凹陷除发育下古新统月桂峰组湖相烃源岩外,还发育有中古新统灵峰组浅海相烃源岩。基于以上对烃源岩的分析,提出了丽水西凹陷下一步的油气勘探目标,即凹中断背斜构造背景上的岩性圈闭、凹中断鼻及其构造背景上的岩性圈闭和仙桥构造带,为寻找丽水西凹陷新的油气储量阵地提供新的认识。     

Control Factors and Diversities of Phase State of Oil and Gas Pools in the Kuqa Petroleum System

Based on the analysis of the hydrocarbon geochemical characteristics in the Kuqa petroleum system of the Tarim Basin, this study discusses the causes and controlling factors of the phase diversities and their differences in geochemical features. According to the characteristics and differences in oil and gas phase, the petroleum system can be divided into five categories: oil reservoir, wet gas reservoir, condensate gas-rich reservoir, condensate gas-poor reservoir and dry gas reservoir. The causes for the diversities in oil and gas phases include diversities of the sources of parent material, maturity of natural gas and the process of hydrocarbon accumulation of different hydrocarbon phases. On the whole, the Jurassic and Triassic terrestrial source rocks are the main sources for the hydrocarbon in the Kuqa Depression. The small differences in parent material may cause diversities in oil and gas amount, but the impact is small. The differences in oil and gas phase are mainly affected by maturity and the accumulation process, which closely relates with each other. Oil and gas at different thermal evolution stage can be captured in different accumulation process.     

Analysis of Reservoir Forming Conditions and Prediction of Continuous Tight Gas Reservoirs for the Deep Jurassic in the Eastern Kuqa Depression, Tarim Basin

The exploration targets in the Kuqa Depression at present are mainly structure traps in Cretaceous-Tertiary. Due to the complexity of mountain distribution and reservoir forming conditions, the exploration of Jurassic in the eastern Kuqa Depression has been in a state of semi-stagnation since the discovery of the Yinan-2 gas reservoir. According to the concept and theory of “continuous petroleum reservoirs” and the re-analysis of the forming conditions of the Yinan-2 gas reservoir and regional natural gas in the eastern Kuqa Depression, it is believed that the deep Jurassic has good natural gas accumulation conditions as well as geological conditions for forming continuous tight gas reservoirs. The boundary of the Yinan-2 gas reservoir is not controlled by a structural spillpoint. The downdip part of the structure is dominated by gas, while the hanging wall of the fault is filled by water and forming obvious inverted gas and water. The gas reservoir has the normal temperature and ultra-high pressure which formed in the near source or inner-source. All of these characteristics indicate that the Yinan-2 gas reservoir is different from conventional gas reservoirs. The deep Jurassic in the eastern Kuqa Depression has multisets of source-reservoir-cap assemblages, which comprise interbedded sandstones and mudstones. These assemblages are characterized by a self-generation, self-preserving and self-coverage model. Reservoir sandstones and coal measure mudstones are interbedded with each other at a large scale. As the source rocks, Triassic-Jurassic coal measure mudstones distribute continuously at a large scale and can generate and expel hydrocarbon. Source rocks contact intimately with the overlying sandstone reservoirs. During the late stage of hydrocarbon expulsion, natural gas charged continuously and directly into the neighboring reservoirs. Petroleum migrated mainly in a vertical direction over short distances. With ultra-high pressure and strong charging intensity, natural gas accumulated continuously. Reservoirs are dominated by sandstones of braided delta facies. The sand bodies distribute continuously horizontal. With low porosity and low permeability, the reservoirs are featured by strong heterogeneity. It is hypothesized that the sandstones of the interior depression tend to be relatively tight with increasing depth and structure stress weakness. Thus, it is predicted that continuous tight gas reservoirs of ultra-high pressure may exist in the deep formations of the eastern and even the whole Kuqa Depression. So, it is worth evaluating the exploration potential.     

塔里木盆地柯克亚地区天然气和凝析油的地球化学特征与成区

柯克亚气田的油气成因复杂，对原油和可能烃源岩的分子标志物特征进行了剖析，在凝析油中检测到3-甲基甾烷，不含4-甲基甾烷，富含重排藿烷和C30^-未知萜烷．表明油源主要来自于二叠系源岩。柯克亚的天然气重烃含量高，属湿气，乙烷碳同位素偏重；天然气氩同位素和成熟度特征均指示混源气特征，通过气源判识天然气主要来源于石炭系一二叠系源岩，部分来源于侏罗系源岩。天然气的乙烷δ^13C值明显重于凝析油全油δ^13C值，揭示柯克亚地区凝析油和天然气分属不同来源。     

塔里木盆地柯克亚地区天然气和凝析油的地球化学特征与成因

柯克亚气田的油气成因复杂,对原油和可能烃源岩的分子标志物特征进行了剖析,在凝析油中检测到3-甲基甾烷,不含4-甲基甾烷,富含重排藿烷和C30-未知萜烷,表明油源主要来自于二叠系源岩。柯克亚的天然气重烃含量高,属湿气,乙烷碳同位素偏重;天然气氩同位素和成熟度特征均指示混源气特征,通过气源判识天然气主要来源于石炭系—二叠系源岩,部分来源于侏罗系源岩。天然气的乙烷δ13C值明显重于凝析油全油δ13C值,揭示柯克亚地区凝析油和天然气分属不同来源。     

Different Hydrocarbon Accumulation Histories in the Kelasu-Yiqikelike Structural Belt of the Kuqa Foreland Basin

<正>The Kuqa foreland basin is an important petroliferous basin where gas predominates.The Kela-2 large natural gas reservoir and the Yinan-2,Dabei-1,Tuzi and Dina-11 gas reservoirs have been discovered in the basin up to the present.Natural gases in the Kelasu district and the Yinan district are generated from different source rocks indicated by methane and ethane carbon isotopes.The former is derived from both Jurassic and Triassic source rocks,while the latter is mainly from the Jurassic. Based on its multistage evolution and superposition and the intense tectonic transformation in the basin,the hydrocarbon charging history can be divided into the early and middle Himalayan hydrocarbon accumulation and the late Himalayan redistribution and re-enrichment.The heavier carbon isotope composition and the high natural gas ratio of C_1/C_(1-4) indicate that the accumulated natural gas in the early Himalayan stage is destroyed and the present trapped natural gas was charged mainly in the middle and late Himalayan stages.Comparison and contrast of the oils produced in the Kelasu and Yinan regions indicate the hydrocarbon charging histories in the above two regions are complex and should be characterized by multistage hydrocarbon migration and accumulation.     

应用生烃动力学方法研究库车坳陷烃源岩生烃史

根据烃源岩生烃动力学参数,结合沉积埋藏史和古热史资料,本文应用生烃动力学方法研究了塔里木盆地库车坳陷三叠-侏罗纪烃源岩生烃史。研究表明,无论是煤,还是泥岩,库车坳陷三叠-侏罗纪烃源岩生气时间发生得晚,主生气期出现在10 Ma以来的喜山期晚期,生气高峰期出现在5 Ma之后。中上三叠世烃源岩生气时间和主生气期均早于中下侏罗世烃源岩。烃源岩这种晚期生气特征,为库车坳陷天然气的晚期聚集成藏提供了非常有利的烃源条件。