浅析中国中西部盆地煤系烃源岩成烃研究

烃源岩作为石油、天然气的母源 ,在油气地质研究和油气勘探中占有相当重的位置。伴随着传统生油理论“源控论”的发展 ,煤系烃源岩的发展也得到广泛的关注 ,其研究内容也不断拓展。根据煤系烃源岩的有机质丰度及相关指标 ,指出煤系烃源岩可以成烃 ,只是作为未成熟—低成熟的向油气转化阶段 ,同时也能够在一定条件下成为具有工业性价值的煤系地层油气藏。中国西北部地区广泛存在煤系地层 ,同时也发现煤系有机质转化为烃类 ,对比西北部 ,中国中西部的含煤地层 ,存在构造的复杂因素 ,在转化过程中考虑的因素很多 ,因此在研究煤系地层的成烃作用时 ,必须慎重 ,结合综合指标才能判断     

New insights into marine hydrocarbon geological conditions in the South Yellow Sea Basin: evidence from borehole CSDP-2

The South Yellow Sea Basin(SYSB) has multiple sets of proven source rocks and good hydrocarbon prospects,but no industrial oil and gas has been explored at present.To solve this puzzle for petroleum geologists,we systematically investigated the marine hydrocarbon geological conditions based on cores and testing data from borehole CSDP-2,the first exploration well with continuous coring in SYSB.The qualities of source rocks are evaluated in detail according to organic matter abundance,type,and maturity.The reservoir characterization mainly includes porosity,permeability,and reservoir space.Displacement pressure test and stratum thickness are the main foundations for defining the caprocks.Then,the oil-source rock correlation in the Permian and stratum model are analyzed to determine the favorable source-reservoir-caprock assemblages.The results show that three sets of effective source rocks(the Lower Triassic,Upper Permian,and Lower Permian),two sets of tight sandstone re servoirs(the Upper Permian and Lower Silurian-Upper Devonian),and two sets of caprocks(the Lower Triassic and Carboniferous) combine to constitute the hydrocarbon reservoir-forming as se mblages of "lower-ge neration and upper-accumlation" and "self-generation and self-accumlation",thus laying a solid foundation for promising petroleum prospects.The three sets of marine source rocks are characterized by successive generation and expulsion stages,which guarantees multistage hydrocarbon accumulation.Another three sets of continental source rocks distributed across the Middle Jurassic,Upper Cretaceous,and Paleogene depression areas,especially in the Northern Depression,may supplement some hydrocarbons for the Central Uplift through faults and the Indosinian unconformity.The favorable Permian exploration strata have been identified in the Central Uplift of SYSB.First,the Lower Permian and Upper Permian source rocks with high organic matter abundance and high thermal maturity supply sufficient hydrocarbons.Secondly,the interbedding relationship between the source rocks and sandstones in the Upper Permian strata ensures that hydrocarbons have been migrated into the nearby Upper Permian sandstones,reflecting near-source hydrocarbon accumulation.Finally,the good sealing property of the Lower Triassic Qinglong Formation caprocks plays an indispensable role in hydrocarbon preservation of the Permian reservoirs.This conclusion is supported by direct oil shows,gas logging anomalous layers,and hydrocarbon-bearing fluid inclusions.     

Organic geochemistry and source rock potential assessment of Late Paleocene Patala Formation in Margalla Hill Range,North Pakistan

Black shales of the Paleocene Patala Formation are proven source rocks for conventional hydrocarbons in southern Potwar Basin of Pakistan and are assumed to be effective source rocks towards north in the Margalla Hill Range of Pakistan. In this regard, the current study focuses on source rock geochemistry of the Paleocene Patala Formation to assess its source rock potential, organic matter types and thermal maturity levels in the Mar-galla Hill Range of North Pakistan. Source rock generative potential, kerogen types and thermal maturation of the analysed rock samples were unraveled by using Rock-Eval pyrolysis Tmax, TOC (total organic carbon) and vitrinite reflectance ( R0 ) analyses. TOC analysis coupled with S2 yield revealed poor to fair source rock quality encountered within the formation. The pyrolysis Tmax vs Hydrogen Index ( HI) , showed mostly Type Ⅲ kerogen dominated by thermally immature to mature organic matter. The HI and genetic potential is low and revealed poor hydrocarbon generation potential of the formation. The S1 vs TOC plots confirm the indigenous nature of the hydrocarbons hosted by Patala Formation. The vitrinite reflectance outcomes indicated immature to mature source rock beds lying in dry gas zone. The HI and OI signatures and abundance of Type Ⅲ kerogen are indica-ting dominance of terrestrial organic matter within the formation. Overall, the investigated Patala Formation ex-posed at the studied section of Margalla Hill Range, Pakistan acts as a poor source rock unit for liquid hydrocar-bon generation but holds prospects for dry gas generation in the study area.     

珠江口盆地惠西南地区凝析油轻烃地球化学特征

惠西南地区是珠江口盆地珠一坳陷重要的原油富集区, 但近年来在新近系珠江组上段和古近系恩平组、文昌组以及基岩潜山储层中陆续发现了凝析油气。利用全油气相色谱和饱和烃色谱-质谱分析技术对凝析油样开展了轻烃和生物标志化合物地球化学特征分析, 探讨了惠西南地区凝析油的成因。研究表明: 轻烃组分特征、C₇异构烷烃、环烷烃及正构烷烃和生物标志化合物特征均指示H6-1构造凝析油来源于半深湖-深湖相文昌组烃源岩, 为腐泥型烃源岩在相对高成熟阶段(R_o处于1.2%~1.3%)生成的凝析油; H1-1构造凝析油来源于浅湖沼泽相恩平组烃源岩, 为偏腐殖型烃源岩在相对低成熟阶段(R_o处于0.9%~1.1%)生成的富低碳数烷烃油气; 揭示了惠西南凝析油的形成受到烃源母质类型和热演化阶段的双重控制。研究结果为富油生烃凹陷凝析油气勘探潜力评价分析提供了地球化学依据和支撑。      

西湖凹陷中央反转带中北部天然气高效成藏主控因素及富集规律

西湖凹陷中央反转带中北部大型气田成藏因素及动态匹配关系至今不明。通过针对烃源岩、储层、输导体系及成藏期等成藏关键因素进行系统分析,建立"源-储-圈-输"的动态成藏过程分析中央反转带中北部大气田的成藏主控因素。研究表明始新统宝石组与平湖组煤系烃源岩不仅生气强度大,而且中新世晚期以来的快速生、排气为中央反转带中北部的大中型天然气藏提供了充足油气源;花港组小于4 000 m地层的酸性地层水是形成有利储层的关键;中新世晚期发生的龙井运动强烈挤压作用使中央反转带发生了构造变形和断层开启活动,为圈闭和油气输导通道的形成创造了条件。综合"源-储-圈-输"分析认为成藏主控因素在生烃期的有机耦合造就了始新统煤系烃源岩高效生气及天然气的有效运移聚集成藏的全过程。本次研究为研究区大气田的勘探提供了借鉴。      

东海盆地西湖凹陷平湖组煤系烃源岩条件及成烃模式

西湖凹陷是中国近海最重要的煤成油气凹陷。近年来，油气勘探证实平湖组煤系烃源岩为西湖凹陷提供了丰富的油气资源。与陆上其他中生代煤成油气盆地不同，近海新生代海陆过渡相平湖组煤系烃源岩在母质来源、生烃条件和演化特征上都有其独特性。研究表明，平湖组煤和炭质泥岩具有富含树脂体、高I_H指数、Ⅱ₁-Ⅱ₂型干酪根、广覆式分布特点；煤系烃源岩富含三环二萜异海松烷、四环二萜β-扁植烷和五环三萜奥利烷，指示了针叶类裸子植物、蕨类植物和被子植物多植被母质来源；有机质组成差异、"内热外冷"地温和差异的沉积沉降速率造成了煤和泥岩在不同构造带成烃演化具有明显不同。这种差异决定了煤成油气资源具有"油气并举、东气西油"的分布格局，烃源岩成烃演化表现为"早期有利生油，晚期持续生气"模式。      

Accumulation model and prediction of Miocene heavy oil distribution in Gulf of Suez Basin,Egypt

The Gulf of Suez Basin is a very mature and extremely prospective petroleum province.Many heavy oil fields have been found in the Basin, and such reserves are abundant.Characteristics and models of heavy oil are analyzed in this study based on tectonic, basin evolution, stratigraphic distribution and geochemical data. The best reservoirs of heavy oil are Miocene sandstone and limestone formations.Source rocks of hydrocarbon include deep limestone and shale of the Brown Limestone, the Thebes Formation and the Rudeis Formation. Thick evaporite rocks with rock salts and anhydrites deposited broadly throughout the basin are the most impor-tant regional seals, whereas Miocene shales are intraformational and regional seals that cover small areas.Heavy oil could be directly generated or densified during vertical migration along faults and reservoir accumulation. The heavy oil accumulation model is a mixed model that includes three mechanisms:fault dispersal, sulfocom-pound reactions and hydrocarbons generated from immature source rock.After analyzing the model and the dis-tribution of source rocks, reservoirs, heavy oil fields and structures, it is concluded that the potential heavy oil area is at the center of the basin.     

煤系烃源岩与石英次生加大边的形成机理探讨:以鄂尔多斯盆地东部山西组为例

借助有机酸热模拟、岩石薄片及阴极发光实验资料,分析了鄂尔多斯东部地区山西组煤系烃源岩与石英次生加大边的关系。研究表明:煤系烃源岩以Ⅲ型干酪根为主,在热演化生烃的过程中由于含氧基团逐步断裂产生了大量的有机酸;在酸性微孔隙环境下,石英砂岩及其岩屑石英砂岩中的火山喷出岩屑、长石等不稳定矿物易遭受溶蚀,形成的SiO₂提供了石英次生加大的硅质来源,薄片及阴极发光下均可观察到石英发育多期次生加大,尤以二期次生加大为主;证实煤系烃源岩中的有机酸是导致石英发生多期次生加大的直接原因,最终形成致密砂岩。      

甘蒙地区北山盆地群中口子盆地侏罗系烃源岩特征及评价

北山盆地群侏罗系是我国西北地区潜在的油气勘探新领域,为深化其石油地质认识,进一步明确资源潜力,优选北山盆地群中勘探程度相对较高的中口子盆地侏罗系为研究对象,以有机质丰度、类型及成熟度等有机地球化学分析数据为基础,分析了侏罗系烃源岩基础特征,并基于生物标志化合物资料,探讨了该区侏罗系烃源岩的有机质来源及沉积环境。结果表明,中口子盆地侏罗系烃源岩有机质丰度较高,生烃潜力较好,主要为中等-好烃源岩,干酪根类型以Ⅱ2型为主,生烃母质主要是陆源高等植物,主要形成于氧气量适中的弱氧化-弱还原古环境,靠近或位于凹陷中心的烃源岩形成环境还原性稍强,较有利于有机质保存。区内黑帐房凹陷烃源岩已经成熟,而南泉凹陷烃源岩主要为低熟。因此建议黑帐房凹陷中心或者临近中心区域,寻找保存条件好的油藏是取得下步油气勘探突破的重点。这些认识可供西北地区侏罗系沉积古环境和资源潜力研究时对比参考。     

Gas accumulation mechanism in Denglouku Formation of Changling fault depression,southern Songliao Basin,China

The Changling gas field is occurs in tight sandstone reservoirs of the Lower Cretaceous Denglouku Formation in the Changling fault depression , southern Songliao Basin , China, which constitutes a new gas-pro-ducing area in the depression .Using information on the source-reservoir-cap rock assemblage of the Denglouku Formation, fault activity, and single well burial history of well CS 1, together with data on reservoir fluid inclu-sion and laser Raman spectroscopy , we described the formation of the Changling gas field and determine that this fault depression did not possess suitable conditions for hydrocarbon generation .Coal-derived methane gen-erated from underlying hydrocarbon source rock accumulated in the Lower Cretaceous Yingcheng Formation .At the end of the Late Cretaceous Qingshankou Stage , underwater volcanic eruptions occurred in the northern part of the Changling gas field near Qian'an, resulting in the reactivation of deep faults .Mantle-sourced inorganic CO2 migrated along faults to hydrocarbon gas reservoirs in volcanic rocks of the Yingcheng Formation ;Mean-while, displaced methane ( hydrocarbon gas ) migrated upward to sand reservoirs of the Denglouku Formation . The methane accumulated and formed secondary gas reservoirs ,Therefore fault activity was the main factor con-trolling the generation of gas reservoirs in the Denglouku Formation .The main accumulation period of the Yingcheng hydrocarbon gas reservoirs was 82 Ma.Whereas gas reservoir formation in the overlying Denglongku Formation was 79 Ma, slightly later than the time of formation of the Yingcheng gas reservoir in CS 1 well area. At 79 Ma, the burial depth of the Denglouku Formation was 1800-2000 m, the diagenesis is relatively weak and the physical properties of the reservoir are relatively favorable for accumulation .This period is not only at gas generation peak time of three sets of source rock but also at the reactivation of deep faults during the forma -tion of fault-bound depressions , thereby providing favorable conditions for the migration and accumulation of methane .     

东非裂谷Albertine盆地上中新统—下上新统烃源岩地球化学特征与沉积环境

Albertine盆地是东非裂谷系重要的裂谷盆地, 油气资源丰富, 上中新统-下上新统烃源岩是盆地重要的生烃岩系, 目前研究相对薄弱。综合利用地质学、岩石热解、元素地球化学等资料, 对Albertine盆地上中新统和下上新统的烃源岩进行了评价, 并分析了晚中新世-早上新世时期的古环境特征。研究表明, 两套烃源岩处于成熟阶段, 但有机质丰度和类型存在差异, 下上新统烃源岩有机质丰度更高, 属于中等-好烃源岩, 干酪根类型主要是Ⅱ₁~Ⅱ₂型; 上中新统烃源岩有机质丰度略低, 属于差烃源岩, 干酪根主要是Ⅱ₂~Ⅲ型。沉积环境是造成烃源岩差异的重要原因。晚中新世-早上新世时期, 研究区属于还原性较强的淡水湖盆, 水体逐渐加深, 气候越来越温暖, 细菌及微生物繁盛, 有机质类型变好, 同时, 湖泊生产力提高, 沉积速率有所加快, 有机质能够更有效地保存, 烃源岩的有机质丰度更高。研究结果对于Albertine盆地的油气勘探与开发具有重要的理论意义和实际意义。      

鄂尔多斯盆地东胜地区侏罗系煤与铀矿关系

鄂尔多斯盆地东胜地区侏罗系煤与砂岩型铀矿在空间上密切共存,为探讨煤与铀矿的关系,进行了广泛的野外调研和系统的室内分析。在煤岩特征、煤的成岩演化和煤地球化学特征研究的基础上,发现从泥炭至褐煤的煤化过程中,铀的含量不断增加;铀含量与煤岩显微组分中的镜质组含量成正比;砂岩成岩矿物与煤化作用有关;煤的微量元素和稀土元素的含量特征与含矿砂岩具一致性。研究认为,在同生成岩阶段和早成岩阶段,煤对铀的作用主要包括吸附作用、络合作用及还原作用;表生成岩阶段,煤对铀的再分配和“保矿”起到积极作用。     

Geochemical characteristics of Early Cretaceous source rocks in Boli Basin

The Early Cretaceous deposits are composed of important source rocks in Boli Basin. The types of the source rocks include black mudstones and coal (with carbonaceous mudstone). By the organic geochemical analysis methods, the authors discussed the organic petrological characters, abundance of organic matter, degree of maturity and the type of source rocks. The main micro-component of black mudstone is exinite or vitrinite, and the content of vitrinite is high in coal. The weathering of the outcrop is very serious. The abundance of organic matter in source rock reaches the poor to better rank. The major kerogens in mudstone are type-Ⅲ, type-Ⅱ2 and some type-Ⅱ1; the organic type of coal is type-Ⅲ. The thermal evolution of the source rocks in every structural unit is very different, from low-maturity to over-maturity. The depositional environment is reductive, which is good for the preservation of organic matter. The organic matter in source rocks is mainly from aquatic organisms and terrigenous input.     

Tectonic Evolution and Geological Characteristics of Hydrocarbon Reservoirs in Marine Mesozoic–Paleozoic Strata in the South Yellow Sea Basin

The South Yellow Sea Basin is the main body of the lower Yangtze area in which marine Mesozoic–Paleozoic strata are widely distributed.The latest geophysical data were used to overcome the limitation of previous poor-quality deep data.Meanwhile,the geological characteristics of hydrocarbon reservoirs in the marine Mesozoic–Paleozoic strata in the South Yellow Sea Basin were analyzed by comparing the source rocks and the reservoir and utilizing drilling and outcrop data.It is believed that the South Yellow Sea Basin roughly underwent six evolutionary stages:plate spreading,plate convergence,stable platform development,foreland basin development,faulted basin development,and depression basin development.The South Yellow Sea Basin has characteristics of a composite platform-fault depression geological structure,with a half-graben geological structure and with a ‘sandwich structure' in the vertical direction.Four sets of hydrocarbon source rocks developed – the upper Permian Longtan–Dalong formation,the lower Permian Qixia formation,the lower Silurian Gaojiabian formation,and the lower Cambrian Hetang formation/Mufushan formation,giving the South Yellow Sea Basin relatively good hydrocarbon potential.The carbonate is the main reservoir rock type in the South Yellow Sea area,and there are four carbonate reservoir types:porous dolomitic,reef-bank,weathered crust,and fractured.There are reservoir-forming horizons similar to the typical hydrocarbon reservoirs in the Yangtze land area developed in the South Yellow Sea,and there are three sets of complete source-reservoir-cap rock assemblages developed in the marine strata,with very good hydrocarbon potential.     

塔里木盆地东北部侏罗系烃源岩特征及初步评价

塔里木盆地是中国最大的含油气盆地,其东北部的侏罗系分布面积广、厚度大,主要发育一套煤系烃源岩.根据钻井及大量的实验测试等资料,研究了侏罗系煤系烃源岩的发育特征及其有机地球化学、有机岩石学特征,表明其有机质丰度较高,达到中等-好级别;有机质类型以Ⅲ型为主、Ⅱ型为辅;有机质热演化程度处于未成熟-低成熟阶段,部分地区可能达成熟阶段;烃源岩主要生烃显微组分为基质镜质体,少量孢子体、角质体和碎屑壳质体.综合分析表明,塔里木盆地侏罗系烃源岩具备一定的生烃条件和油气勘探前景.     

泌阳凹陷下二门地区核桃园组油气成藏再认识

泌阳凹陷下二门地区位于泌阳凹陷东部,区内已发现下二门油田。该油田在核三上段至核二段下部为纯油藏,核二段上部为具气顶的油藏,核一段和廖庄组为纯气藏。经过40多年勘探开发,在下二门地区油气藏的发现难度越来越大,油气勘探陷入瓶颈期。为了进一步扩大该区勘探规模,取得新的油气发现,需要对该地区油气成藏机制再认识进而决定其下一步勘探方向。利用最新勘探和油藏资料,通过烃源条件分析、油源对比、天然气成分分析及油藏精细解剖,重新认识了该地区油气成藏机制。研究结果表明:泌阳凹陷深凹区的核二段泥页岩发育广,生烃指标较好,已进入低成熟阶段,具备较好的生油条件;下二门地区各层系油气与深凹区的源岩关系明确,表明油气以顺层运移为主,即核二段低熟油应该来自深凹区核二段低熟烃源岩,核三上段和核三下段原油分别来自深凹区核三上段和核三下段的成熟烃源岩;下二门地区核二段产出的天然气为低成熟伴生气,明显不同于深层凝析气,并非深层油气沿断层调整而来;下二门地区深层油气资源量大,但目前已发现储量规模有限,这预示着该区仍有较大的勘探潜力。因此,总结下二门地区的油气成藏特点及成藏模式,不仅可为该区油气勘探提供指导,而且可为我国东部类似断陷湖盆含油构造的进一步勘探提供借鉴。      

渤海湾盆地渤中凹陷古近系烃源岩生物标志物特征及其地质意义

渤中凹陷位于渤海湾盆地中东部, 主要发育沙三、沙一和东三段烃源岩层, 具有良好的油气勘探前景, 前期对渤中凹陷有机地球化学特征的研究主要基于岩屑样品, 对岩心样品生物标志物特征的研究比较薄弱。本次研究综合利用岩心和岩屑样品, 通过有机碳、岩石热解、氯仿沥青"A"、族组分饱和烃色谱-质谱等有机地球化学分析测试, 重点对渤中凹陷古近系东营组三段和沙河街组一段、三段烃源岩的有机质丰度、类型、成熟度及母质来源与沉积环境进行研究, 明确了渤中凹陷三套泥页岩的地球化学特征及发育控制因素, 并建立了区分3套烃源岩的典型生物标志化合物组合特征, 以期望为进一步厘清该区域优质烃源岩发育模式及时空分布提供一定的理论依据, 进而有利于该区油气的勘探。研究结果表明: 3套烃源岩的生烃潜力具有显著差异, 沙三段>沙一段>东三段。沙三段烃源岩有机质丰度最高, 为好-极好烃源岩, 有机质类型为Ⅰ-Ⅱ₁型, 处于成熟阶段; 沙一段次之, 为中等-好烃源岩, 有机质类型为Ⅱ₁-Ⅱ₂型, 整体处于成熟阶段; 东三段稍差, 为中等烃源岩, 有机质类型以Ⅱ₁-Ⅱ₂型为主, 处于低熟-成熟阶段。岩心样品的生物标志化合物中姥植比(Pr/Ph)、伽马蜡烷指数(Ga/C₃₀H)、C₂₇-C₂₈-C₂₉规则甾烷含量、4-甲基甾烷指数(4-MS/C₂₉甾烷)等参数表明母质输入和沉积环境是控制3套湖相烃源岩差异的主控因素, 淡水藻源输入和良好的保存条件是沙三段优质烃源岩发育的关键, 低等水生生物输入和强还原的保存条件是沙一段优质烃源岩发育的关键, 混源输入和良好的保存条件是东三段优质烃源岩发育的关键。      

陆相成熟烃源岩区连通砂体对油气运移的控制作用

基于成熟烃源岩稳态连续排烃机制,分析陆相成熟烃源岩区内连通砂体对油气运移的控制作用,并深入探讨烃源岩内砂体与烃源岩的接触面积、砂泥互层烃源岩层系中砂岩含量、砂体物性、砂体分布及其连续性对排烃效率的影响。结果表明:将连通砂体与烃源岩的接触类型分为垂向沉积相变接触型、侧向沉积相变接触型及交错复合接触型,其中前两者是烃源岩-连通砂体的主要接触类型;烃源岩-连通砂体配置组合以在异常压力驱动下的稳态连续排烃为主;烃源岩内砂体与烃源岩的接触面积越大、砂岩含量越大、砂岩物性越好、砂体分布稳定及连续性好有利于成熟烃源岩排烃,则排烃效率越大,进而控制主要排烃方向和资源量。烃源岩内连通砂体对油气二次运移的作用主要取决于其与烃源岩外连通砂体的分布连续性与物性连通性。如果烃源岩内砂体是孤立的,油气无法运移出烃源岩区,则形成烃源岩内油气藏;如果烃源岩内砂体与烃源岩外砂体分布连续且物性连通,则油气运移距离大,可在更为有利的圈闭分布区成藏。     

西湖凹陷古近系地层水中烃类的地球化学特征

作为油气中有机组分残留在地层水中的直接显示，研究地层水中烃类的地球化学特征对分析油气的沉积环境、生源母质、成熟度等具有重要参考意义。通过对西湖凹陷古近系平湖组和花港组地层水萃取烃类分析后发现:烃类来源于氧化环境下的陆源有机质输入，现均已达到成熟-高成熟阶段。其中黄岩构造带、天台构造带和西次凹的烃类以来自黏土矿物含量颇为丰富的泥岩为主，而平湖斜坡带的源岩缺乏黏土矿物，更可能以煤为主。天台构造带的地层水中烃类很特殊，其姥植比异常高，二萜类具有蕨类植物和裸子植物双重贡献的特征，不同于其他构造带的二萜类以裸子植物来源的特点。进一步研究发现天台构造带原油的姥植比和二萜类特征与其地层水一致，同样具有特殊性，且多种芳烃地球化学参数也均不同于其他构造带，因此推断天台构造带的原油是不同于其他构造带的特殊类型。天台构造带地层水中烃类的特殊性是推断其原油为特殊类型的有力入口，对进一步研究天台构造带的特殊原油提供了指示意义。      

InterPreting effects of TOCinert organic content on source rock Potential using S2 vs. TOC graPh in Maamba Coalfield,southern Zambia

The authors Present the effects of the total organic carbon( TOCinert )during Pyrolysis and how it overall affects the estimates of the hydrocarbon index( HI)using the cross Plot S2 vs. TOC graPh. A to...