喀什坳陷石油地质特征

从基底性质、盖层特征、构造、沉积发展等方面对喀什坳陷的石油地质特征进行了概述。指出,坳陷内局部构造十分发育,地面及钻井油气显示丰富,具有良好的生储盖组合,侏罗系为主力生油层,其次为上白垩统一下第三系生油岩,储层主要有上侏罗统库孜贡苏组、下白垩统克孜勒苏群砂砾岩及下第三系碳酸盐岩;盖层主要为上白垩统一下第三系古新统、中新统泥岩和膏泥岩层。在坳陷内既可寻找侏罗系自生自储油藏,也可寻找以中侏罗统杨叶组为生油层以白垩系为储油层的古生新储油气藏,同时也可寻找以第三系为油源的原生油气藏及次生油气藏。     

塔里木盆地西南坳陷下白垩统沉积相与储集层差异演化特征

下白垩统是塔里木盆地西南坳陷主要的勘探层系之一,油气资源丰富但勘探程度较低,新近部署的多口探井均遭遇失利。为指导油气勘探部署,利用露头、钻井、地震和实验分析等资料,对下白垩统残余分布、沉积体系类型及储集层差异演化特征进行了研究。结果表明：①下白垩统沿南天山和昆仑山山前存在喀什北缘、乌泊尔构造带、棋北构造带和柯东构造带4个集中分布区,从山前向盆地内部减薄尖灭,改变了以往呈连续带状分布的认识。②古地貌控制下发育辫状河三角洲和扇三角洲2种沉积体系;其中,辫状河三角洲以前缘亚相为主,厚层水道砂体叠置连片分布,而扇三角洲由平原和前缘亚相构成,具有厚层短轴粗粒特征。③受原始沉积组分和后期成岩改造影响,下白垩统发育次生孔隙型和原生孔隙型2类储层,储集物性表现为中低孔中低渗—特低孔特低渗差异分布,喀什北缘和柯东构造带有利储层相对发育。     

民和盆地的构造特征

根据地震、重磁力与露头资料的分析,认为民和盆地具有双层结构,前期(上白垩统沉积前)为断陷,后期(下白垩统沉积后)为拗陷,是中新生代发展起来的断、拗山间沉积盆地;盆地基底为复合基底,即前寒武系变质岩和加里东褶皱带的花岗岩;将局部构造归纳为6种类型的构造样式,分属于扭动、冲断与基岩生长3大构造组合。      

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松辽盆地浅层气藏是指下白垩统嫩江组二，三，四段和上白垩统明水组一段含气层。钻探证实，具工业气流，且多数分布在盆地中央拗陷区的萨尔图，新北，葡萄花，龙虎泡，木头，红岗油田和敖南鼻状构造等之上的浅部地层。气源主要来自中部含油气组合和嫩一，二段生油层，不排除少量生物气的混入。嫩二，三，四段及明一段的砂岩组为气藏储集空间，粉－细砂岩为主，岩性疏松，孔隙度在２５％以上。嫩三段黑色泥岩在盆地内稳定分布，为嫩二     

塔里木盆地喀什凹陷北部油砂分布特征

喀什凹陷北部地表构造出露有多处油砂,分布层位主要是中新统安居安组和帕卡布拉克组,次为下白垩统克孜勒苏群。在构造的轴部及靠近轴部的两翼,断裂发育,是油砂分布的有利部位。油砂含油性与岩性关系密切,含油率较高的油砂岩性主要是细砂岩、中细砂岩。喀什凹陷北部油砂的油源来自于侏罗系烃源岩,成藏期为中新世至上新世。上新世晚期的构造运动破坏了早期形成的油藏,在喀什凹陷北部地表形成油砂。     

试论松辽大型陆相湖盆水进三角洲沉积相

松辽盆地是我国东部陆相大型含油盆地,主要由上侏罗统及白垩系组成,盆地经历了断陷期(晚侏罗世)—拗陷期(早白垩世)—萎缩期(晚白垩世—第三纪)三个发展阶段。盆地内已经发现的含油气层主要集中在下白垩统的拗陷期的沉积层内,包括泉四段(扶余油层)、青山口组(高台子油层)、姚家组(萨尔图、葡萄花油层)、嫩江组(黑帝庙油层),其中主要生产层为萨尔图、葡萄花油层(表1)。青山口组、姚家组沉积时期,在盆地北、西、东三个方向发育有四个河湖三角洲沉积体系,自边缘向中央拗陷深湖区延展,其中以北安—杏树岗三角洲为最大,面积达4.4万平方公里;保康三角洲次之;英台三角洲、齐齐哈尔三角洲更次之。      

桂中拗陷下泥盆统郁江阶—下石炭统生油运移期与构造配置关系初探

桂中拗陷是在加里东褶皱基底上发育起来的沉积拗陷。上古生界至中三叠统,海相沉积厚逾万米。其中下泥盆统郁江阶至下石炭统,最大沉积厚度可达5500多米。地表油气显示类型多、分布广,为本区找油(气)主要目的层。然而,后期改造强烈,对油气的生成、运移、聚集和破坏有很大的影响。      

潮汕坳陷中生界——油气勘探的新领域

近年的研究表明,潮汕坳陷是珠江口盆地的一个大型残留坳陷,其内沉积了上三叠统一下侏罗统、下白垩统和上白垩统等3套海相地层。潮汕坳陷含油气系统有别于珠江口盆地其它凹陷,其烃源岩、储层和益层均为中生代地层,并具有大型构造圈闭．且构造与油气远聚关系匹配良好,将成为珠江口盆地最有希望的后备油气勘探区。     

SYNTHETIC EVALUATION OF SOURCE ROCKS IN SOUTHWEST DEPRESSION OF THE TARIM BASIN

塔里木盆地西南坳陷主要沉积上第三系、上白垩统－下第三系、中下侏罗统、石炭－二叠系和寒武－奥陶系5套生油岩。寒武－奥陶系沉积中心在阿瓦提凹陷和塘古巴斯凹陷,有机质丰度高、类型好、成熟度高,是该区主要油气源岩。石炭系－下二叠统烃源岩分布广、丰度及类型多样、成熟度中到高,是该区次要油气源岩。侏罗系及下第三系生油岩是喀什凹陷、西南缘区主要生油岩。上第三系烃源岩主要分布于叶城凹陷山前区。     

潮汕坳陷中生界——油气勘探的新领域

近年的研究表明 ,潮汕坳陷是珠江口盆地的一个大型残留坳陷 ,其内沉积了上三叠统—下侏罗统、下白垩统和上白垩统等 3套海相地层。潮汕坳陷含油气系统有别于珠江口盆地其它凹陷 ,其烃源岩、储层和盖层均为中生代地层 ,并具有大型构造圈闭 ,且构造与油气运聚关系匹配良好 ,将成为珠江口盆地最有希望的后备油气勘探区。     

PETROLEUM SYSTEMS OF THE BONGOR BASIN AND THE GREAT BAOBAB OILFIELD,SOUTHERN CHAD

The Bongor Basin in southern Chad is an inverted rift basin located on Precambrian crystalline basement which is linked regionally to the Mesozoic – Cenozoic Western and Central African Rift System. Pay zones present in nearby rift basins (e.g. Upper Cretaceous and Paleogene reservoirs overlying Lower Cretaceous source rocks) are absent from the Bongor Basin, having been removed during latest Cretaceous – Paleogene inversion-related uplift and erosion. This study characterizes the petroleum system of the Bongor Basin through systematic analyses of source rocks, reservoirs and cap rocks. Geochemical analyses of core plug samples of dark mudstones indicate that source rock intervals are present in Lower Cretaceous lacustrine shales of the Mimosa and upper Prosopis Formations. In addition, these mudstones are confirmed as a regional seal. Reservoir units include both Lower Cretaceous sandstones and Precambrian basement rocks, and mature source rocks may also act as a potential reservoir for shale oil. Dominant structural styles are large-scale inversion anticlines in the Lower Cretaceous succession whilst underlying “buried hill” -type basement plays may also be important. Accumulations of heavy to light oils and gas have been discovered in Lower Cretaceous sandstones and basement reservoirs. The Great Baobab field, the largest discovery in the Bongor Basin with about 1.5 billion barrels of oil in-place, is located in the Northern Slope, a structural unit near the northern margin of the basin. Reservoirs are Lower Cretaceous syn-rift sandstones and weathered and fractured zones in the crystalline basement. The field currently produces about 32,000 barrels of oil per day.     

华北加里东侵蚀面与油气富集

本文叙述华北地区加里东侵蚀面即奥陶纪海相碳酸盐岩顶面(Tg波组)的划分和对海相碳酸盐岩油气藏形成的控制。此面沉积间断时间长达1.3亿年,缺失志留、泥盆系和下石炭统,侵蚀面上下地层为平行不整合接触。由于长期裸露地表,遭受风化、淋滤、溶蚀、剥蚀,奥陶纪碳酸盐岩的溶孔(洞)、溶缝甚为发育,是极好的油气储集岩。华北地区古生界碳酸盐岩大油气藏的油气源岩,除其自身外,下第三系更是重要的油气源岩。油气生成后,通过断裂、不整合面等通道,聚集在加里东侵蚀面上下的圈闭中,形成高产油气藏。      

MATURITY AND PETROLEUM SYSTEMS MODELLING IN THE OFFSHORE ZAMBEZI DELTA DEPRESSION AND ANGOCHE BASIN,NORTHERN MOZAMBIQUE

Petroleum systems analysis and maturity modelling is used to predict the timing and locations of hydrocarbon generation in the underexplored offshore Zambezi Delta depression and Angoche basin, northern Mozambique. Model inputs include available geological, geochemical and geophysical data. Based on recent plate‐tectonic reconstructions and regional correlations, the presence of Valanginian and Middle and/or Late Jurassic marine source rock is proposed in the study area. The stratigraphy of the Mozambique margin was interpreted along reflection seismic lines and tied to four wells in the Zambezi Delta depression. Thermal maturity was calibrated against measured vitrinite reflectance values from these four wells. Four 1‐D models with calibration data were constructed, together with another five without calibration data at pseudo‐well locations, and indicate the maturity of possible source rocks in the Zambezi Delta depressions and Angoche basin. Two 2‐D petroleum systems models, constrained by seismic reflection data, depict the burial history and maturity evolution of the Zambezi Delta basin. With the exception of the deeply‐buried centre of the Zambezi Delta depression where potential Jurassic and Lower Cretaceous source rocks were found to be overmature for both oil and gas, modelling showed that potential source rocks in the remaining parts of the study area are mature for hydrocarbon generation. In both the Zambezi Delta depression and Angoche basin, indications for natural gas may be explained by early maturation of oil‐prone source rocks and secondary oil cracking, which likely began in the Early Cretaceous. In distal parts of the Angoche basin, however, the proposed source rocks remain in the oil window.     

PETROLEUM GEOLOGY AND HYDROCARBON POTENTIAL OF THE ADRIATIC BASIN,OFFSHORE CROATIA

Offshore Croatia is a relatively underexplored area with no oilfields currently on production. Exploration commenced in 1970 and several biogenic gas fields were subsequently discovered producing from shallow Plio‐Pleistocene reservoir rocks in the northern Adriatic area; however, exploration wells drilled for oil in Mesozoic carbonates have failed, although several wells encountered oil shows. Using data from the Croatian and Italian Adriatic, we provide in this paper some new insights into the Mesozoic palaeogeography and hydrocarbon plays of offshore Croatia. Offshore Croatia has been divided into three areas – north, central and south – with distinctive geological characteristics and hydrocarbon systems. The effects and importance of halokinesis in the eastern Adriatic is described and its influence on the petroleum systems is discussed. The evaluation of a modern, regional, high‐resolution dataset has enhanced our understanding of the Adriatic Basin and supports the presence of petroleum systems with potential mature source rocks in shales from the Triassic succession, supplying reservoir rocks in Jurassic and Cretaceous carbonate platform margins/slope talus plays, and Cenozoic siliciclastic plays.     

位于巨型走滑断裂端部盆地演化的地质模型——以苏丹穆格莱德盆地为例

横跨非洲大陆中部巨型中非断裂带东端的穆格莱德盆地的演化与周邻的大地构造背景密切相关。在早白垩世的演化与大西洋的分阶段张裂密切相关,晚白垩世的演化与印度块体的快速北移有关,新生代的演化主要和红海的扩张有关。盆地的构造演化可划分三大阶段:在早白垩世盆地发育的鼎盛时期,受中非走滑断裂的影响,盆地沉降速率巨大,沉积中心和沉降中心往往不一致;在晚白垩世,盆地为断陷和坳陷型沉积,沉积中心向远离中非断裂带的东南方向迁移。盆地总体的演化具有从走滑型向拉张伸展型转化的特点。在盆地演化的早期,烃源岩和储集岩在靠近中非走滑断裂带附近较发育;在晚期的构造挤压作用下,一方面对已形成的油气藏进行破坏,同时,可造成油气重新分布,形成一些新生的油气藏。在该部位沉降中心和沉积中心往往不一致,这给油气的勘探带来新的困难,因此对这些地区的勘探要十分慎重。在远离中非断裂带的盆地东南部,是晚期沉积和沉降的中心,主力烃源岩演化比较适中,油气成藏期较晚,是寻找具有工业价值油气田的有利部位。      

东海西湖凹陷含油气系统特征

东海西湖凹陷自晚白垩纪以来,经历了 3个发展阶段,形成了平湖组花港组、花港组和始新统 3套含油气系统,其中,前两套为已知系统,后者为推测系统。两套已知系统的烃源岩现今均处于成熟阶段,花港组含油气系统的盖层自南而北封闭性变差,其中南部的油气勘探更具现实意义。综合分析表明:平湖组花港组含油气系统的关键时刻在距今 7Ma左右,花港组含油气系统在距今 1.64Ma左右。     

湖相碳酸盐岩的石油地质意义

本文主要对湖相碳酸盐岩的生油能力、储集条件、油气藏类型以及对湖相碳酸盐岩隐蔽油气藏的勘探方法进行了规律性的讨论和总结。认为半深湖和深湖相碳酸盐岩可成为良好的生油岩;滩相和生物礁相灰(云)岩可成为良好的储集层;其储集空间可有原生孔隙、次生溶孔和溶洞、裂缝及复合型孔缝等;油气藏类型以岩性、地层圈闭为主,也有成岩圈闭和构造圈闭类型。此外,还从不同角度对湖相碳酸盐岩隐蔽油气藏的研究手段和勘探方法进行了概括性总结。      

AN OVERVIEW OF THE PETROLEUM SYSTEMS IN THE IONIAN ZONE,ONSHORE NW GREECE AND ALBANIA

The Ionian and Gavrovo Zones in the external Hellenide fold‐and‐thrust belt of western Greece are a southern extension of the proven Albanian oil and gas province. Two petroleum systems have been identified here: a Mesozoic mainly oil‐prone system, and a Cenozoic system with gas potential. Potential Mesozoic source rocks include organic‐rich shales within Triassic evaporites and dissolution‐collapse breccias; marls at the base of the Early Jurassic (lower Toarcian) Ammonitico Rosso; the Lower and Upper Posidonia beds (Toarcian–Aalenian and Callovian–Tithonian respectively); and the Late Cretaceous (Cenomanian–Turonian) Vigla Shales, part of the Vigla Limestone Formation. These potential source rocks contain Types I‐II kerogen and are mature for oil generation if sufficiently deeply buried. The Vigla Shales have TOC up to 2.5% and good to excellent hydrocarbon generation potential with kerogen Type II. Potential Cenozoic gas‐prone source rocks with Type III kerogen comprise organic‐rich intervals in Eocene–Oligocene and Aquitanian–Burdigalian submarine fan deposits, which may generate biogenic gas. The complex regional deformation history of the external Hellenide foldbelt, with periods of both crustal extension and shortening, has resulted in the development of structural traps. Mesozoic extensional structures have been overprinted by later Hellenide thrusts, and favourable trap locations may occur along thrust back‐limbs and in the crests of anticlines. Trapping geometries may also be provided by lateral discontinuities in the basal detachment in the thin‐skinned fold‐and‐thrust belt, or associated with strike‐slip fault zones. Regional‐scale seals are provided by Triassic evaporites, and Eocene‐Oligocene and Neogene shales. Onshore oil‐ and gasfields in Albania are located in the Peri‐Adriatic Depression and Ionian Zone. Numerous oil seeps have been recorded in the Kruja Zone but no commercial hydrocarbon accumulations. Source rocks in the Ionian Zone comprise Upper Triassic – Lower Jurassic carbonates and shales of Middle Jurassic, Late Jurassic and Early Cretaceous ages. Reservoir rocks in both oil‐ and gas‐fields in general consist of silicilastics in the Peri‐Adriatic Depression succession and the underlying Cretaceous–Eocene carbonates with minimal primary porosity improved by fracturing in the Albanian Ionian Zone. Oil accumulations in thrust‐related structures are sealed by the overlying Oligocene flysch whereas seals for gas accumulations are provided by Upper Miocene–Pliocene shales. Thin‐kinned thrusting along flysch décollements, resulting in stacked carbonate sequences, has clearly been demonstrated on seismic profiles and in well data, possibly enhanced by evaporitic horizons. Offshore Albania in the South Adriatic basin, exploration targets in the SW include possible compressional structures and topographic highs proximal to the relatively unstructured boundary of the Apulian platform. Further to the north, there is potential for oil accumulations both in the overpressured siliciclastic section and in the underlying deeply buried platform carbonates. Biogenic gas potential is related to structures in the overpressured Neogene (Miocene–Pliocene) succession.     

PETROLEUM GEOLOGY OF THE UNITED ARAB EMIRATES

The Permain to Holocene sediments of the United Arab Emirates consist mainly of epeiric shelf carbonates, associated with minor clastics and evaporites, reflecting major cycles of transgression and regression. These were deposited on the eastern margin of the Arabian Sheild, which lay along the southern margin of the Tethys Ocean during the Mesozoic-Cenozoic eras. Sedimentation patterns were controlled by prominent regional structural features, epeirogenic movements and/or sea-level fluctuations.
The tectonic history of the UAE in the Mesozoic-Cenozoic is connected with the opening (Triassic) and closure (Upper Cretaceous-Paleogene) of the southern Neo-Tethys Ocean.
The distinctive structural style, together with the tripartite development of source-reservoir-seal, has produced in the UAE one of the world's richest Jurassic - Cretaceous oil habitats. Significant oil discoveries have also been made in the Permian; Middle and Upper Jurassic; Lower-Middle-Upper Cretaceous and Oligo-Miocene carbonates.
Two main source rocks have been identified. One is the Upper Jurassic Diyab/Dukhan Formation, which supplies the most prolific reservoirs in the Upper Jurassic (Arab Formation) and Lower Cretaceous (Thamama Group). The other is the Middle Cretaceous Shilaif/Khatiyah Formation, which feeds both Mishrif and Simsima reservoirs. Other minor potential source rocks have also been identified in the study area.
There are two principal sealing formations - the Hith Anhydrite and the Nahr Umr shale; these are the main seals for the oil and gas accumulations in the underlying Arab Formation and Thamama Group, respectively. Secondary seals and barriers also exist in the stratigraphic sequence.     

THE INFLUENCE OF TECTONICS ON THE ENTRAPMENT OF OIL IN THE DEZFUL EMBAYMENT, ZAGROS FOLDBELT, IRAN

The timing of the orogenic events associated with the closure of South Tethys significantly influenced the generation, migration and entrapment of petroleum in the Zagros Foldbelt of Iran. This influence was particularly important in the Dezful Embayment, which is one of the world's richest oil provinces, containing some 8% of global oil reserves in an area of only 60,000 sq. km. In the Dezful Embayment, oil and associated gas occur in two carbonate reservoirs ‐ the Sarvak Formation of Cenomanian to Turonian age, and the Oligocene ‐ Early Miocene Asmari Formation, sealed by the evaporites of the Gachsaran Formation. The oil and associated gas are trapped in large “whaleback” anticlines which formed during the Neogene Zagros orogeny. Two excellent source rocks, the Albian Kazhdumi Formation and the upper part of the Pabdeh Formation (Middle Eocene to Early Oligocene), supplied the Asmari and Sarvak reservoirs and with them form the Middle Cretaceous to Early Miocene Petroleum System. This system was found to be independent of older petroleum systems. Two particular problems are addressed in this paper. The first is the relative timing of trap formation versus oil expulsion from the source rocks. If oil expulsion occurred prior to Zagros folding, the oil would have migrated along gently dipping ramps towards the Persian (Arabian) Gulf and Southern Iraq, and would have been trapped a long way from the source kitchen. By contrast, if oil expulsion took place when the whaleback anticlines already existed or had at least begun to develop, the oil generated would have moved almost vertically towards the nearest anticline. Secondly, we assess the type of heatflow to be used for modelling. This could be either variable or constant, depending on the stability or instability of the Arabian Platform and on subsidence variations during source rock maturation. Our conclusions can be summarized as follows. First, the paroxysmal phase of Zagros folding commenced in the Dezful Embayment towards the end of the Middle Miocene around 10 Ma ago and continued throughout the Late Miocene and Pliocene. Second, bearing in mind the remarkable stability of the Arabian Platform for some 260 Ma, during which there was almost continuous gentle subsidence between the Permian transgression and the Early Miocene, a constant heatflow was used for modelling. Burial profiles and maturity indices, such as vitrinite reflectance and Rock‐Eval parameters, demonstrate that the Kazhdumi and Pabdeh source rocks reached the onset of oil expulsion during deposition of the Agha Jari Formation between 8 and 3Ma, depending upon the location. This chronology means that oil migrated from source rocks into preexisting Zagros structures. Therefore, oil migrated over short distances to nearby traps within well‐defined drainage areas, the geometry of which can be deduced from seismic data. Moreover, the Zagros folding induced prominent fracturing which can be observed both at outcrop and in wells. This fracturing, which affects lime‐stones as well as marls, enhanced subvertical migration of hydrocarbons towards the reservoirs. As a result of this short distance migration, oils can directly be linked to the source rocks which generated them by oil‐oil and oil‐source rock correlations based on stable isotope (σ¹³C, σ³⁴S) and biomarker data. Modelling of each drainage area provides estimates of the amount of oil expelled by each source rock. Calculated estimates can then be compared to the actual oil‐in‐place of the corresponding field. An example of this modeling procedure is given in this paper.