Assessing the maturity of oil trapped in fluid inclusions using molecular geochemistry data and visually-determined fluorescence colours

The thermal maturity of oils extracted from inclusions and the fluorescence colours of oil-bearing fluid inclusions have been measured in 36 sandstone samples from Australasian oil fields. The inclusion oils were analysed using an off-line crushing technique followed by GC–MS. A maturity assessment was made for each inclusion oil using 25 molecular maturity ratios, including a newly defined dimethyldibenzothiophene ratio (DMDR). Each inclusion oil was placed in one of 4 maturity brackets, approximately equivalent to early, mid, peak and post oil generation windows. The fluorescence colours of oil inclusions were visually-discriminated into “blue”, “white” and “yellow plus orange” and their proportions estimated using point counting techniques. Sixteen samples have >85% of oil inclusions with blue fluorescence, whilst other samples have more variable fluorescence colours. One sample has 100% of oil inclusions with yellow plus orange fluorescence. The results show that samples containing mainly blue-fluorescing oil inclusions have thermal maturities anywhere within the oil window. In particular, the molecular geochemical data strongly suggests that oil inclusions with blue fluorescence can have relatively low maturities (calculated reflectance <0.65%), contrary to the widely applied assumption that blue fluorescence colours indicate high maturities. Samples containing mainly white-fluorescing oil inclusions have maturities anywhere within the oil window and cannot be distinguished using molecular geochemical parameters from samples containing mainly blue-fluorescing oil inclusions. Though few in number, samples with mainly yellow and orange-fluorescing oil inclusions tend to have maturities in the lower half of the oil window. The data presented strongly suggest that although the relationship between API gravity and the fluorescence properties of crude oils is well established, the extension of this relationship to the use of the fluorescence colours of oil inclusions as a qualitative thermal maturity guide is not justified. Fluorescence colour depends in the first instance on chemical composition, which is controlled not only by maturity but by several other processes. For example, inclusions in samples from below current or residual oil zones in the Timor Sea contain a high proportion of yellow- and orange-fluorescing oil inclusions compared to the overlying oil zones, which are dominated by blue-fluorescing oil inclusions. This observation is interpreted to be due to water washing causing molecular and gross fractionation of oils prior to trapping. Fractionation of the gross composition of oil during the inclusion trapping process may also be a significant controlling process on the fluorescence colours of oil inclusions, due to the preferential adsorption of polar compounds onto charged mineral surfaces. A trapping control is strongly supported by synthetic oil inclusion work. Care should be taken when interpreting the charge history of samples containing oil inclusions with mixed fluorescence colour populations, such as those from the Iagifu-7x well in the Papuan Basin. It is possible that the different colour populations represent a single oil charge, with oil inclusions trapped under slightly different conditions or at slightly different grain surfaces, rather than multiple migration events.     

The application of fluid inclusions to migration of oil and diagenesis in petroleum reservoirs

Fluid inclusions can be used to interpret thermal history and petroleum maturation and migration relative to burial history. Temperature, pressure and composition data collected from fluid inclusions are used to determine the environment of diagenesis and the timing of cementation and migration. Cements in petroleum reservoirs contain both oil and aqueous fluid inclusions. Fluorescence spectroscopy is used to identify oil inclusions and to determine the maturity of entrapped oil. The lifetime of fluorescence induced by a pulsed laser is related to the API gravity of entrapped oil. Interpretation of fluid inclusion data depends on knowing the origin of fluid inclusions and the probability that they survive in the burial environment. Those aspects of fluid inclusion study are investigated by synthesizing oil and aqueous inclusions in calcite crystals in laboratory experiments. Examples of how fluid inclusions are used to determine the physico-chemical environments of diagenesis in petroleum reservoirs and the timing of cementation and migration are given for the Wealden Basin, England, the Mishrif Formation, Dubai, the Smackover Formation, Gulf Coast, U.S.A. and Jurassic sandstones, offshore Norway. In the Wealden Basin, temperature data from fluid inclusions are used to determine that oil migration occurred in the Cretaceous and that the reservoir rocks have been uplifted to varying degrees at a time after migration. Distribution of oil inclusions indicates that generation and migration of oil was principally in the western part of the basin. The geochemistry of oil inclusions in calcite cements from the Mishrif Formation, Dubai, are used to determine the type and maturity of entrapped oil. Temperature data from oil and water inclusions are used to relate reservoir diagenesis to burial history and the migration of oil. In deep Smackover reservoirs oil contains H₂S. The origin of the H₂S is examined by study of fluid inclusions containing H₂S. In Jurassic sandstones, offshore Norway, fluid inclusion studies show that silica cementation is related to burial depth whereas a later calcite cementation originated from invasion of a hot fluid.     

Origin of oils in the Eastern Papuan Basin,Papua New Guinea

The geochemical characteristics of 16 oils/condensates/seep oil/oil shows (collectively called oils) from the Eastern Papuan Basin (EPB) and one seep oil from the Western Papuan Basin (WPB) are integrated with data from previous studies of oils, fluid inclusion oils and solid bitumens from the EPB and WPB, Papua New Guinea. The combined set of samples can be divided in two major families of hydrocarbons. The Family A oils, mostly occurring in the WPB region, were generated from clay rich marine source rocks, containing predominantly terrigenous higher plant derived organic matter (OM) deposited in a sub-oxic to oxic environment. Source rock(s) for Family A oils are likely to be of Middle to Upper Jurassic, e.g., the Upper Jurassic Imburu Formation. The Family B oils, distributed mainly in the EPB region, were generated from Cretaceous or younger marine carbonate source rock(s) deposited under anoxic to sub-oxic conditions, and containing predominantly prokaryotic OM with some terrigenous higher plant inputs. The EPB natural gases analyzed in this study may be co-genetic to the co-occurring Family B oils in the EPB. Both Family A and B oils were generated at similar thermal maturities of 1.0–1.3% vitrinite reflectance equivalent. Although no source interval to date has been firmly identified in the EPB, post-Jurassic strata are a viable option, because (1) Late Cretaceous and Paleogene carbonate and clastic marine sediments including possible source lithologies are present, and (2) this section of the Papuan Basin sustained rapid sedimentation and tectonic loading, particularly in the Cenozoic.     

含油流体包裹体：地球化学分析与地质应用

利用含油流体包裹体可以获得与原油和源区常规分析同等质量的可靠地球化学数据。细致而又小心谨慎地对待各测试步骤(如样品清洗、背景空白等)是成功进行包裹体油气成分分析的基础。从技术上来说，每一分析步骤都具有挑战性，但如果我们能按步骤循序渐进，就不仅能够分析那些含有大量石油包裹体的样品(如当今或古油藏样品)，而且可以测试含极少量石油包裹体的样品(如迁移路径或极古老岩石样品)。包裹体中可被测试的碳氢化合物多种多样，包括低分子量的碳氢化合物、n-链烷、类异戊二烯、生物标志物、芳香族碳氢化合物等。流体包裹体内石油成分分析在地质上有广泛应用，比如可以更好地重建储集区石油重注史、确定盆地中以前未知的活性源岩。在储集区内由生物降解造成的石油再造和(或)水洗作用经常被抹去，流体包襄体分析则可以解释储集区复杂成油阶段，当然更可以去除钻孔泥浆添加剂或其他污染物的影响。此外，也可以获知地球早期生物圈碳氢化合物的组成及多样性，以及在勘探区或盆地进行二次迁移路径填图。     

Characteristics of Oil Sources from the Chepaizi Swell,Junggar Basin,China

<正>So far there has been no common opinion on oil source of the Chepaizi swell in the Junggar Basin.Therefore,it is difficult to determine the pathway system and trend of hydrocarbon migration, and this resulted in difficulties in study of oil-gas accumulation patterns.In this paper,study of nitrogen compounds distribution in oils from Chepaizi was carried out in order to classify source rocks of oils stored in different reservoirs in the study area.Then,migration characteristics of oils from the same source were investigated by using nitrogen compounds parameters.The results of nitrogen compounds in a group of oil/oil sand samples from the same source indicate that the oils trapped in the Chepaizi swell experienced an obvious vertical migration.With increasing migration distance,amounts and indices of carbazoles have a regular changing pattern(in a fine linear relationship).By using nitrogen compounds techniques,the analyzed oil/oil sand samples of Chepaizi can be classified into two groups.One is the samples stored in reservoir beds of the Cretaceous and Tertiary,and these oils came from mainly Jurassic source rock with a small amount of Cretaceous rock;the other is those stored in the Jurassic,Permian and Carboniferous beds,and they originated from the Permian source.In addition,a sample of oil from an upper Jurassic reservoir(Well Ka 6), which was generated from Jurassic coal source rock,has a totally different nitrogen compound distribution from those of the above-mentioned two groups of samples,which were generated from mudstone sources.Because of influence from fractionation of oil migration,amounts and ratios of nitrogen compounds with different structures and polarities change regularly with increasing migrating distance,and as a result the samples with the same source follow a good linear relationship in content and ratio,while the oil samples of different sources have obviously different nitrogen compound distribution owing to different organic matter types of their source rocks.These conclusions of oil source study are identical with those obtained by other geochemical bio-markers. Therefore,nitrogen compounds are of great significance in oil type classification and oil/source correlation.     

准噶尔盆地四棵树凹陷烃源岩地球化学特征及其对车排子凸起油气聚集的贡献

准噶尔盆地西南缘四棵树凹陷主要分布侏罗系、白垩系和古近系3套潜在烃源岩,其中侏罗系八道湾组烃源岩有机质丰度较高,有机质类型以Ⅲ型为主,部分为Ⅱ2型,生烃潜力较高;三工河组烃源岩有机质丰度、类型明显偏差,生烃潜力较低;西山窑组泥岩有机质丰度较高,但由于受西山窑组沉积末期构造抬升导致地层剥蚀的影响,烃源岩厚度较小,总体上生烃条件较差;白垩系烃源岩在四棵树凹陷最大厚度可达300 m,处于低熟阶段,生烃潜力较小;古近系烃源岩有机质丰度较高、类型好,但成熟度偏低,生烃条件较差。侏罗系八道湾组烃源岩处于主要生油阶段;白垩系烃源岩已达到生烃门限,处于低熟—中等成熟阶段;古近系烃源岩成熟度偏低,目前仍处于未熟到低熟阶段。油源对比表明,四棵树凹陷北部斜坡及车排子凸起带原油主要来源于四棵树凹陷及沙湾凹陷侏罗系烃源灶,后期受到白垩系低熟油源灶的侵染,古近系烃源岩的油源贡献有限。     

焉耆盆地三工河组储层流体包裹体形成期次分析

焉耆盆地三工河组流体包裹体具有丰度低、个体小的特征,并以液态烃相包裹体为主,主要分布在石英颗粒的溶孔或溶缝当中。结合盆地成岩作用和有机质演化历史分析,认为它们形成于侏罗纪晚期的以压溶和溶蚀作用为特征的晚成岩作用阶段。包裹体均一温度呈双峰型分布,具有 10 1~ 110℃和 12 1~ 130℃两个区间,结合焉耆盆地的埋藏史和盆地的热史,这两个温度区间分别对应于晚侏罗世和侏罗纪末期。包裹体组份特征分析也证实该地区存在两期包裹体,并且包裹体组分主要是在烃源岩低成熟阶段形成的。可以认为,焉耆盆地三工河组储层的流体包裹体主要是在晚侏罗世烃源岩的低成熟阶段和侏罗纪末期烃源岩的成熟阶段形成。     

二连盆地侏罗系烃源岩地球化学特征及油源贡献

二连盆地侏罗系烃源岩研究程度较低,但在侏罗系发现有工业油流.本文通过有机岩石学与有机地球化学常规分析,系统研究与评价了此套烃源岩;结合原油与烃源岩的生物标志化合物的对比与分析,探讨其对油源的贡献.结果表明,二连盆地上侏罗统烃源岩有机质丰度低,有机质类型以Ⅲ型为主,成熟度较低,为非或差烃源岩;中下侏罗统有机质丰度较高,有机质类型以Ⅱ2-Ⅲ型为主,成熟度较高,为较好—好烃源岩.侏罗系烃源岩形成于淡水的氧化沉积环境,以陆源高等植物输入为主.此外,阿56井阿尔善组部分原油和图参1井侏罗系原油来源于侏罗系烃源岩.由此推断二连盆地侏罗系烃源岩具有良好的生烃潜力,勘探前景广阔.     

羌塘盆地中生代古油藏油源问题探讨

对羌塘盆地中生界共242个露头烃源岩样品以及6个油苗样品进行了正构烷烃碳数分布模式,多环芳烃系列相对含量组成,甾烷组成,甾、萜系列相对含量等多项测试对比研究。岩样分布于侏罗系索瓦组、夏里组、布曲组、色哇组、曲色组以及上三叠统肖查卡组这六套主要烃源岩层系,油样分布于雪山组、索瓦组、夏里组以及布曲组。布曲组烃源岩是多个不同地层古油藏的主要贡献者,是羌塘盆地的主力烃源岩层系之一;雪山组古油藏很可能另有主力油源层,它与所述的六套烃源岩均无可比性。     

Preservation of hydrocarbons and biomarkers in oil trapped inside fluid inclusions for >2 billion years

Oil-bearing fluid inclusions occur in a ca. 2.45 Ga fluvial metaconglomerate of the Matinenda Formation at Elliot Lake, Canada. The oil, most likely derived from the conformably overlying deltaic McKim Formation, was trapped in quartz and feldspar during diagenesis and early metamorphism of the host rock, probably before ca. 2.2 Ga. Molecular geochemical analyses of the oil reveal a wide range of compounds, including CH₄, CO₂, n-alkanes, isoprenoids, monomethylalkanes, aromatic hydrocarbons, low molecular weight cyclic hydrocarbons, and trace amounts of complex multi-ring biomarkers. Maturity ratios show that the oil was generated in the oil window, with no evidence of extensive thermal cracking. This is remarkable, given that the oils were exposed to upper prehnite-pumpellyite facies metamorphism (280-350 °C) either during migration or after entrapment. The fluid inclusions are closed systems, with high fluid pressures, and contain no clays or other minerals or metals that might catalyse oil-to-gas cracking. These three attributes may all contribute to the thermal stability of the included oil and enable survival of biomarkers and molecular ratios over billions of years. The biomarker geochemistry of the oil in the Matinenda Formation fluid inclusions enables inferences about the organisms that contributed to the organic matter deposited in the Palaeoproterozoic source rocks from which the analysed oil was generated and expelled. The presence of biomarkers produced by cyanobacteria and eukaryotes that are derived from and trapped in rocks deposited before ca. 2.2 Ga is consistent with an earlier evolution of oxygenic photosynthesis and suggests that some aquatic settings had become sufficiently oxygenated for sterol biosynthesis by this time. The extraction of biomarker molecules from Palaeoproterozoic oil-bearing fluid inclusions thus establishes a new method, using low detection limits and system blank levels, to trace evolution through Earth’s early history that avoids the potential contamination problems affecting shale-hosted hydrocarbons.     

海拉尔盆地乌尔逊凹陷石油运移模式与成藏期

海拉尔盆地由多个凹陷构成, 油气潜在资源丰富.研究含油凹陷油气的来源、油气充注方向及成藏时间对指导盆地油气勘探具有理论和现实意义.以乌尔逊凹陷为例, 采用生物标志化合物及含氮化合物定量分析技术, 研究了石油的来源及运移方向; 利用自生伊利石K-Ar同位素测年法、源岩生排烃史法及储层流体包裹体测温法, 探讨了石油成藏期.结果表明, 原油主要来源于凹陷南部“烃源灶”内的南屯组生油岩, 油气成藏中发生了侧向运移.通源大断裂是油气运移的主要通道, 断层两盘的构造圈闭是油气聚集成藏的有利部位.苏仁诺尔构造带石油沿断裂向北东方向运移, 最大距离可达20 km.乌尔逊凹陷有3次成藏期, 其中距今100 Ma左右的伊敏组沉积末期是该区的主要成藏期.凹陷中随油藏与“烃源灶”距离的减小, 成藏期呈现逐渐变晚的趋势.      

马朗凹陷断裂-烃源岩空间配置关系与石油垂向运移特征

马朗凹陷的原油类型可以划分为3大类,Ⅰ类原油来自二叠系芦草沟组,Ⅱ类原油来自石炭系哈尔加乌组,Ⅲ类原油为Ⅰ与Ⅱ类原油的混源油。通过断裂活动强度、垂向输导断裂与烃源岩的匹配关系的研究,结合原油含氮化合物的分析资料,分析了马朗凹陷油气的垂向运移特征。研究表明,断层的断裂活动强度控制着油气的垂向运移能力,垂向输导断裂与烃源岩相匹配时,烃源岩生成的油气才能向上运移至上覆地层聚集成藏。二叠系芦草沟组烃源岩厚度中心附近的垂向输导断裂断穿侏罗系,所以,芦草沟组烃源岩生成的Ⅰ类原油可以运移至侏罗系聚集成藏,而石炭系哈尔加乌组烃源岩附近的断裂大都未断至二叠系和侏罗系,所以哈尔加乌组烃源岩生成的Ⅱ类原油未能运移到侏罗系聚集成藏,而主要在石炭系成藏。与断裂输导分析相配合,含氮化合物可以很好示踪油气的垂向运移方向,沿断裂从深层到浅层,原油含氮化合物总浓度逐渐降低,1,8DMC/1,3 DMC或1,8DMC/2,4 DMC值增大。     

渤海湾盆地南堡凹陷油气运移路径模拟及示踪

在油气成藏期分析的基础上, 采用盆地流线模拟技术对渤海湾盆地南堡凹陷成藏关键时刻油气运移过程进行了恢复, 根据原油含氮化合物和成熟度指标对典型油气富集区的油气运移路径进行了示踪.油气运移路径模拟结果表明, 研究区南部凹槽源内和源下油气藏在东营末期(距今24.6 Ma)有一期较小规模运移, 油气大规模运移时期为明化镇中期(距今9 Ma).南部凹槽源上油气藏和北部凹槽源内油气藏在明化镇中期有少量油气运移, 大规模运移时期为明化镇末期(距今2 Ma).目前南部凹槽勘探程度较低, 模拟结果表明其具有较大的勘探潜力.原油地球化学指标揭示在源上油气藏富集区, 对于伸入洼陷中心的油源断层, 油气主要沿断层走向, 向构造高部位及断层面两侧砂体运移; 对于平行洼陷中心的油源断层, 油气主要沿断层倾向向构造高部位运移.在源内油气藏富集区, 油气主要通过有效烃源岩层系内发育的砂体向构造高部位运移.      

Hydrocarbon potential of the Sargelu Formation,North Iraq

Microscopic and chemical analysis of 85 rock samples from exploratory wells and outcrops in northern Iraq indicate that limestone, black shale and marl within the Middle Jurassic Sargelu Formation contain abundant oil-prone organic matter. For example, one 7-m (23-ft.)-thick section averages 442 mg?HC/g S2 and 439 °C Tmax (Rock-Eval pyrolysis analyses) and 16 wt.% TOC. The organic matter, comprised principally of brazinophyte algae, dinoflagellate cysts, spores, pollen, foraminiferal test linings and phytoclasts, was deposited in a distal, suboxic to anoxic basin and can be correlated with kerogens classified as type A and type B or, alternatively, as type II. The level of thermal maturity is within the oil window with TAI?=?3^? to 3⁺, based on microspore colour of light yellowish brown to brown. Accordingly, good hydrocarbon generation potential is predicted for this formation. Terpane and sterane biomarker distributions, as well as stable isotope values, were determined for oils and potential source rock extracts to determine valid oil-to-source rock correlations. Two subfamily carbonate oil types—one of Middle Jurassic age (Sargelu) carbonate rock and the other of Upper Jurassic/Cretaceous age—as well as a different oil family related to Triassic marls, were identified based on multivariate statistical analysis (HCA and PCA). Middle Jurassic subfamily A oils from Demir Dagh oil field correlate well with rich, marginally mature, Sargelu source rocks in well MK-2 near the city of Baiji. In contrast, subfamily B oils have a greater proportion of R₂₈ steranes, indicating they were generated from Upper Jurassic/Lower Cretaceous carbonates such as those at Gillabat oil field north of Mansuriyah Lake. Oils from Gillabat field thus indicate a lower degree of correlation with the Sargelu source rocks than do oils from Demir Dagh field. One-dimension petroleum system models of key wells were developed using IES PetroMod Software to evaluate burial-thermal history, source-rock maturity and the timing and extent of petroleum generation; interpreted well logs served as input to the models. The oil-generation potential of sulphur-rich Sargelu source rocks was simulated using closed system type II-S kerogen kinetics. Model results indicate that throughout northern Iraq, generation and expulsion of oil from the Sargelu began and ended in the late Miocene. At present, Jurassic source rocks might have generated and expelled between 70 % and 100 % of their total oil.     

应用烃类流体包裹体GOI和成分研究凝析气藏成藏过程：以准噶尔盆地莫索湾地区为例

The Grains containing Oil Inclusions(GOI)data in currently gas/condensate-beating Jurassic and Cretaceous reservoir sandstones of Well Pen 5(the Mosuowan area of central Junggar Basin,NW China)are generally greater than the empirical threshold line of 5%.This is consistent with the gas-condensate section originally containing a palaeo-oil column.In order to assess the origin of the oil trapped in the oil inclusion and its relationship to the free oil/gas-condensate,a detailed molecular geochemical study was carried out for correlation between the free and inclusion oils.The paleo oil is most likely sourced from the Lower Permian Fengeheng Formation,which generated hydrocarbons primarily during Late Triassic and the oils were later secondarily altered and dysmigrated along faults likely during Late Jurassic-Early Cretaceous.In contrast,the current reservoired oil/gas-condensate mainly derived from the Middle Permian Lower Wuerhe Formation,whose peak generation time last from Late Cretaceous even to the present.This paper showed that integrated oil-bearing fluid inclusion analyses have likely allowed a complex multi-phase charge history to be recognized and resolved with a high degree of confidence.     

Geochemistry of spinel-hosted amphibole inclusions in abyssal peridotite: insight into secondary melt formation in melt–peridotite reaction

Spinel-hosted hydrous silicate mineral inclusions are often observed in dunite and troctolite as well as chromitite. Their origin has been expected as products associated with melt–peridotite reaction, based on the host rock origin. However, the systematics in mineralogical and geochemical features are not yet investigated totally. In this study, we report geochemical variations of the spinel-hosted pargasite inclusions in reacted harzburgite and olivine-rich troctolite collected from Atlantis Massif, an oceanic core complex, in the Mid-Atlantic Ridge. The studied samples are a good example to examine geochemical variations in the inclusions because the origin and geological background of the host rocks have been well constrained, such as the reaction between MORB melt and depleted residual harzburgite beneath the mid-ocean ridge spreading center. The trace-element compositions of the pargasite inclusions are characterized by not only high abundance of incompatible elements but also the LREE and HFSE enrichments. Distinctive trace-element partitioning between the pargasite inclusion and the host-rock clinopyroxene supports that the secondary melt instantaneously formed by the reaction is trapped in spinel and produces inclusion minerals. While the pargasite geochemical features can be interpreted by modal change reaction of residual harzburgite, such as combination of orthopyroxene decomposition and olivine precipitation, degree of the LREE enrichment as well as variation of HREE abundance is controlled by melt/rock ratio in the reaction. The spinel-hosted hydrous inclusion could be embedded evidence indicating melt–peridotite reaction even if reaction signatures in the host rock were hidden by other consequent reactions.     

准噶尔盆地永进地区油源研究

在分析和归纳可能烃源岩的有机地化特征并对原油样品进行分析测试的基础上,主要运用生物标志物和稳定碳同位素指标或参数,首次对准噶尔盆地永进地区原油的来源进行了系统研究,认为中二叠统和中下侏罗统烃源岩是为该地区提供油源的主要烃源岩,其次为下二叠统烃源岩,并可能有白垩系烃源岩的贡献。其中,中侏罗统西山窑组煤层之上及大部分白垩系储层中的正常原油主要来自中二叠统烃源岩;煤层之下及下侏罗统三工河组储层中的正常原油主要来自中下侏罗统烃源岩;在现今油藏中所占比例较小并已发生强烈生物降解的原油来自下二叠统烃源岩;永6井白垩系储层中的原油可能来自下白垩统烃源岩,但该套烃源岩的供烃规模可能较小。     

准噶尔盆地腹部非均一捕获包裹体研究

不少学者在准噶尔盆地腹部储层砂岩样品中检测到大量的明显高于样品所处地层经历的最高温度的包裹体均一温度数据。经作者研究发现,具有异常高均一温度的包裹体多为捕获自油水非均一体系的三相包裹体,显微镜下即可观察到包裹体内含有气相、液相油和液相水三相,油相在紫外光下发黄色荧光,气相和水相不发荧光,在不同井J₁s、J₁b样品中均有分布,且丰度极高,主要赋存于颗粒愈合裂隙及溶蚀成因的愈合微溶孔和颗粒次生加大边中,多与气态烃包裹体、含气态烃盐水包裹体、盐水包裹体以及纯液体包裹体等不同类型的包裹体共生,均一温度主要分布在130~200℃之间,无明显规律性。综合分析表明,这类包裹体形成于始新世-中新世时研究区内油气调整过程中迁移的油水过渡带中。根据共生的含气态烃盐水包 裹体均一温度,结合埋藏史和热演化史,恢复了包裹体捕获时,为38~17Ma,且浅 部比深部地层中包裹体形成时间较晚,代表了古油水界面到达某一深度的不同时间。     

致密储层石油充注成藏过程分析:以准噶尔盆地吉木萨尔凹陷二叠系芦草沟组为例

作为油气地质领域研究的热点和难点,单一研究手段很难理清致密油充注成藏机理和运聚成藏过程.以准噶尔盆地吉木萨尔凹陷二叠系芦草沟组致密油层为例,通过充注物理模拟实验与成岩-成储-成藏过程分析相结合,分析研究致密油运聚成藏过程.芦草沟组烃源岩自晚三叠世（对应的地层中Ro=0.5%）开始进入生油窗,在中侏罗世（对应的地层中Ro=0.7%）进入大量生烃阶段,至今仍处于生油阶段.烃类包裹体研究表明,吉木萨尔凹陷主要有两期成藏,一期在侏罗纪,包裹体均一温度在50~70 ℃;第二期是在白垩纪-古近纪,包裹体均一温度在120 ℃左右.吉木萨尔凹陷芦草沟组致密储层成岩阶段可划分为三个阶段:①早成岩A期:晚二叠世早期（260 Ma）及之前;②早成岩B期:晚二叠世早期至晚三叠世时期（距今260~220 Ma）;③中成岩A期:晚三叠世至今（220~0 Ma）.根据成岩演化阶段与生烃成藏过程分析,结合致密储层充注模拟实验结论,认为芦草沟组致密油成岩-成储-成藏过程可分为3个阶段:（1）早期储层中-高孔渗条件下低熟油气的充注阶段（晚三叠世之前）;（2）边致密边成藏及改变岩石表面为油润湿性阶段（晚三叠世至早白垩世末期）;（3）芦草沟组致密层中成熟油的持续充注阶段（早白垩世末期至今）.吉木萨尔凹陷芦草沟组致密油资源潜力大,上甜点体（B段）致密油地质资源量约为4.45×108 t,下甜点体（E段）致密油地质资源量约为7.95×108 t.      

准噶尔盆地侏罗系层序地层格架中的烃源岩评价

对准噶尔盆地侏罗系层序地层格架中的烃源岩进行了详细的评价。侏罗系大多数属差-中等的烃源岩,八道湾组比三工河组的生烃条件要好些。在一个层序中,凝缩段的有机碳丰度明显高于湖进体系域段和高位体系域段,即凝缩段有利于烃类的生成。侏罗系的干酪根类型主要为Ⅲ和Ⅱ2,少数为Ⅱ1。侏罗纪并非是典型的成煤沼泽环境,而主要是淡水的滨浅湖-半深湖-深湖环境,主要形成于弱还原-强氧化的地球化学环境中,具有明显的姥鲛烷优势。侏罗系成熟度很低,且不同地区也有所差异,大多数样品处于低成熟阶段 (R_o=0.5 0 %～ 0.80 % ),意味着盆地的侏罗系没有大量生成常规的液态烃类,寻找由侏罗系生成的未熟-低熟油和天然气可能更为现实