拉丁美洲主要沉积盆地类型及典型含油气盆地石油地质特征

拉丁美洲的沉积盆地分成弧前盆地、前陆盆地,被动边缘盆地,内克拉通盆地等类型。以马拉农盆地和坎波斯盆地为例,阐述拉丁美洲最主要的含油气盆地——前陆盆地和被动边缘盆地的石油地质特征。马拉农盆地上白垩统的Chonta组和三叠系—侏罗系Pucara群的烃源岩,Chonta组和Vivian组储层,以及Chonta组和古近系Cachiyacu组的泥岩构成了良好的生储盖组合,下白垩统Cushabtay组高孔、高渗砂岩和活动断层为油气运移提供了有效通道。坎波斯盆地强烈的盐运动在油气运移和成藏过程中起着至关重要的作用,下白垩统LagoaFeia组烃源岩生成的油气经由盐运动形成的盐窗进入上覆浊积岩储层,再经过断层和不整合面的沟通,最终在与盐运动有关的构造圈闭或构造—地层复合圈闭中聚集成藏。     

安第斯山前典型前陆盆地油气成藏特征及主控因素

南美安第斯造山带东侧与圭亚那地盾之间形成了一系列沉积盆地,其构造演化可分为古生代克拉通边缘、中生代弧后裂谷或大陆边缘裂谷、新生代弧后前陆等3 个阶段。白垩系海相泥页岩和碳酸盐岩为主要烃源岩;发育白垩系、古近系和新近系3 大套以砂岩为主的储集层,白垩系裂谷期形成的暗色泥岩和古近系泥岩可作为良好的盖层,纵向上构成了被动陆缘和前陆层序两套储盖组合。山前带构造圈闭发育,油气藏规模大,主要为正常油;斜坡带发育构造、地层等多种圈闭,油藏规模较小,主要为重质油。主造山期形成的构造最有利于捕获油气;优质储集层和断裂构成了油气运移的输导网络;构造破坏和水洗作用使斜坡带多为稠油油藏。     

Oriente-Maranon盆地石油地质特征及勘探潜力

Oriente-Maranon盆地是古生代克拉通边缘基础上发展和形成的次安第斯山(Sub-Andeans)前陆盆地之一,经历了克拉通边缘盆地→裂谷盆地→前陆盆地3个演化阶段。盆地内主要的烃源岩及储、盖组合均发育在裂谷盆地阶段,三叠系—侏罗系Pucara群和白垩系Chonta组2套主要烃源岩的排烃高峰期分别是古新世—始新世(距今60~45 Ma)和中新世(距今15~5 Ma)。Chonta组自生自储组合是最重要的成藏组合。盆地西部发育逆冲断层/褶皱圈闭和基底卷入圈闭,中部发育挤压或披覆背斜,东部发育牵引背斜圈闭,不同类型的圈闭沿北西—南东走向呈带状分布。有潜力的勘探领域包括中西部白垩系Chonta组烃源岩供油区域的披覆和挤压背斜圈闭,中部和南部侏罗系Pucara群烃源岩供油区域的牵引背斜圈闭和挤压背斜圈闭,中部的Pucara群碳酸盐岩圈闭,北部和东部成熟探区上白垩统岩性圈闭和上古生界构造-地层圈闭。图5参13     

秘鲁乌卡亚利盆地油气勘探潜力分析

秘鲁乌卡亚利盆地是油气资源丰富的南美安第斯前陆盆地的子盆地之一。该盆地油气潜力巨大,勘探程度低,已发现12个油气田,可采储量约6×10⁸t。根据大量物探、钻井和实验分析资料,系统分析乌卡亚利盆地的烃源岩、储集层、盖层及圈闭等基本石油地质条件,并提出勘探有利区域和潜力。研究表明,乌卡亚利盆地自奥陶纪形成以来,长期沉降接受沉积。从古生代到中生代沉积3套主要烃源岩,即三叠系-侏罗系Pucara组烃源岩、二叠系Ene组烃源岩和石炭系Ambo群烃源岩,这些烃源岩有机质含量高,处于成熟阶段,分别向盆地的北部、中部和南部运移供油;盆地内有多套储盖组合,主要储集层为白垩系Cushabatay组和Vivian组;晚二叠世以来的多次构造运动特别是晚白垩世以来的构造运动形成多种类型的圈闭,圈闭类型主要为挤压背景下形成的推覆背斜、断背斜和断块等构造圈闭,也存在大量地层和岩性隐蔽圈闭。盆地勘探前景广阔,最有利的勘探区域是盆地东南部的Urubamba次盆和构造发育的西部褶皱逆冲带。已经发现的油气藏全部是构造油气藏而且多数位于逆冲断层的上盘,对下盘圈闭的勘探很少。勘探潜力包括2个方面:一是要继续寻找构造圈闭,特别要加强对逆冲断裂下降盘的勘探力度; 二是要重视隐蔽油气圈闭勘探,特别是要加大二叠系Ene组古潜山圈闭、三叠系-侏罗系Pucara组生物礁圈闭和白垩系岩性(河道砂体)圈闭的勘探。     

秘鲁Maranon盆地油气地质特征及勘探潜力分析

秘鲁Maranon盆地是安第斯山山前的前陆盆地之一。结合该盆地的勘探历史和勘探现状，对相关的钻井、物探以及地球化学等资料进行石油地质综合分析，评价了该盆地的石油地质条件及其勘探潜力。Maranon盆地内有三叠-侏罗系的Pucara组和白垩系的Chonta组两套主要烃源岩，分别于晚侏罗世和始新世开始成熟生烃。Pucara组生成的原油运移至该组地层的剥蚀面，充注至白垩系，但遭到后期造山运动的破坏，通过再次运移聚集成藏；Chonta组生成的原油向盆地东北部运移聚集成藏。盆地内的圈闭类型有背斜、断鼻、断块和地层圈闭等，可能发育多套储盖组合。Maranon盆地西部逆冲-前渊带和无古生界构造圈闭背景的白垩系圈闭、Pucara组碳酸盐岩圈闭以及白垩系Chonta组以下地层潜在的含油气圈闭是该盆地3个重要的潜力勘探领域。图4表1参24     

秘鲁Ucayali盆地油气地质特征及勘探潜力分析

秘鲁Ucayali盆地是位于安第斯山山前的前陆盆地之一,盆地内发育多套储盖组合。盆地内主力烃源岩包括上三叠统—下侏罗统Pucara组和二叠系Ene组的泥岩;发育多套储层,包括白垩系Chonta,Vivian,Cushabatay,Agua Caliente和Raya组储层,以及下二叠统的Ene组砂岩层等;盖层条件良好。北部主要发育基底相关的逆冲断层,而在盆地的南部发育薄皮式的逆冲断层,盆地内已发现的油气田的圈闭类型主要是与逆冲断层相关的断背斜圈闭。北Ucayali次盆Pucara组生成的油气运移至该组地层的剥蚀面,充注至白垩系,但遭到后期造山运动的破坏,通过再次运移聚集成藏。南Ucayali次盆中处于高—过成熟阶段的二叠系Ene组泥岩生成的天然气运移至上覆的二叠系和白垩系储层中。北Ucayali次盆西部的逆冲—前渊带圈闭、Pucara组碳酸盐岩圈闭、二叠系圈闭,以及盆地东部白垩系中的地层岩性圈闭是该盆地4个重要的潜力勘探领域。      

伊川盆地上三叠统油气成藏条件及类型

伊川盆地基底上三叠统发育良好,含大套暗色泥岩,处于晚三叠世洛阳盆地南部沉积中心地带。燕山晚期逆冲推覆构造是伊川地区上三叠统主导构造,逆冲前陆区上三叠统保存较好。伊川盆地上三叠统有机质在早第三纪末—晚第三纪末处于生油高峰期,逆冲前陆区与逆断层有关的早第三纪初构造圈闭和构造—岩性圈闭对上三叠统油气有效。伊川盆地上三叠统具有一定的油气前景,可作为外围新区新层系、新领域油气勘探的突破口。     

西非科特迪瓦盆地石油地质特征及成藏规律研究

科特迪瓦盆地是西非几内亚湾北段一个东西向的具拉分性质的复杂盆地,盆地具有转换大陆边缘与被动大陆边缘叠置的性质.盆地经历了3期构造演化阶段:阿普特期以前为前裂谷期;阿普特期—塞诺曼期早期为裂谷期;塞诺曼期至今为后裂谷期.盆地3期演化相应地建立了不同类型的沉积体系.科特迪瓦盆地已发现的油气聚集区带集中分布在北缘雅克维尔槽地南侧的东西向正向构造带上.油气成藏模式主要是"裂谷层序型成藏模式"和"被动大陆边缘层序型成藏模式".圈闭类型以构造型、构造—不整合型和地层型为主.      

南苏丹Melut盆地北部凹陷古进系及白垩系岩性地层油气藏勘探潜力

Melut盆地北部凹陷为富油气凹陷,具有岩性地层油气藏形成的基本条件。针对深层白垩系和岩性地层油气藏勘探尚未取得突破的现状,通过开展层序地层学和沉积相研究,建立了统一的层序地层格架,明确了Melut盆地北部凹陷源上、源内各主要层序岩性地层油气藏的勘探潜力与方向。研究表明:源上主要发育Yabus上段—Adar—Lau高位域,有利相带为河流、三角洲、扇三角洲,主要形成构造-岩性圈闭;源内主要发育Galhak—Algayger湖侵域,有利相带为三角洲前缘、滑塌浊积扇和洪水浊积扇,主要形成岩性和构造-岩性圈闭。综合分析认为,源内层序是寻找构造-岩性油气藏的主要勘探目标。在有利构造背景下发育良好的储盖组合是Melut盆地白垩系成藏的关键因素,辫状河三角洲前缘相带是白垩系油气成藏的优势相带,上白垩统Galhak组是白垩系油气成藏的主要目的层段。研究结果对Melut盆地北部凹陷下步勘探具有指导意义。     

西非加蓬海岸盆地盐构造及其对成藏组合的控制

西非被动大陆边缘盆地群是近年来全球油气资源的快速增长区。为揭示加蓬海岸盆地的油气富集规律,对盆地的构造特征、盐层序、成藏组合和油气成藏模式进行了研究,结果表明:裂谷期、过渡期和漂移期3个演化阶段中发育的2组近于垂直的NW—SE向和NE—SW向断裂体系形成了东西分带、南北分块的盆地构造格局。盐层序是该盆地油气富集的关键因素,其流动变形形成的盐构造圈闭有利盐上油气聚集成藏;由于不发育盐滑成因的盐窗,盐层序依然保持着连片性,给盐下油气提供了良好的封盖条件。不同时期盐构造演化差异明显,康尼亚克期—始新世早期是盐构造发育的主要时期,对应于第Ⅲ枢纽带活跃期,形成了大量伸展成因的盐构造,盐底辟速率约等于沉积速率,控制了沉积相分布并形成了大量构造或构造—地层圈闭;始新世晚期—渐新世早期,构造反转使局部地区发育挤压成因的无根盐株;后渐新世,盐底辟速率小,对沉积作用影响微弱,有利圈闭发育有限。综合分析表明,盐下有利成藏组合主要发育在第I枢纽带断陷周围的断块和断背斜等圈闭中,盐上有利成藏组合主要分布于第Ⅲ枢纽带西侧浊积扇相区与盐构造圈闭的叠加区。     

THE VENEZUELAN HYDROCARBON HABITAT, PART 2: HYDROCARBON OCCURRENCES AND GENERATED-ACCUMULATED VOLUMES

Venezuela's most important hydrocarbon reserves occur in the intermontane Maracaibo Basin and in the Eastern Venezuela foreland basin. Seeps are abundant in these areas. Lesser volumes occur in the Barinas‐Apure foreland basin. Most of the oil in these basins was derived from the Upper Cretaceous La Luna Formation in the west and its equivalent, the Querecual Formation, in the east. Minor volumes of oil derived from Tertiary source rocks occur in the Maracaibo and Eastern Venezuela Basins and in the Falcdn area. Offshore, several TCF of methane with some associated condensate are present in the Cadpano Basin, and gas is also present in the Columbus Basin. Oil reserves are present in La Vela Bay and in the Gulf of Paria, and oil has been encountered in the Cariaco Basin. The Gulf of Venezuela remains undrilled. The basins between the Netherlands and Venezuelan Antillian Islands seem to lack reservoirs. Tertiary sandstones provide the most important reservoirs, but production comes also from fractured basement (igneous and metamorphic rocks), from basal Cretaceous sandstones and from fractured Cretaceous limestones. Seals are provided by encasing shales, unconformities, faults and tar plugs. There is a wide variety of structural and stratigraphic traps. The Orinoco Heavy Oil Belt of the Eastern Venezuela Basin, one of the world's largest accumulations (1.2 times 10¹² brl) involves stratigraphic trapping provided by onlap and by tar plugging. Stratigraphic trapping involving unconformities and tar plugging also plays a major role also in the Bolivar Coastal complex of fields along the NE margin of Lake Maracaibo. Many of the traps elsewhere in the Maracaibo Basin were influenced by faulting. The faults played an extensional role during Jurassic rifting and subsequently suffered inversion and strike‐slip reactivation. This created anticlines as well as fracture porosity and permeability, and influenced the distribution of sandstone reservoirs, unconformities and related truncation traps. The faults probably also provided migration paths as well as lateral seals. This is very likely the case also in the large, thrust‐related traps of the Furrial Trend in Eastern Venezuela. Normal faults, many antithetic to basement dip, provide important traps in the Las Mercedes, Oficina and Emblador complexes on the southern flanks of the Eastern Venezuela Basin. Similar faults seem to control the Sinco‐Silvestre complex of the Barinas‐Apure Basin. Much of VenezuelaS crude (around 1.5 trillion brls original STOIIP) has been degraded and is heavy, Perhaps two to three trillion brls of precursor, lighter oil existed. While the known Upper Cretaceous La Luna and Querecual Formations are known to include prolific source rocks, a reasonable generation/accumulation efficiency of 10% implies volumes too large to have come from the reported kitchens. The country's vast reserves are perhaps better explained by recognizing that the present‐day basins are remnants of much broader sedimentary areas. The source rocks originally had a much more regional distribution. They suffered widespread, earlier phases of generation that probably charged early‐formed traps on a regional scale. These, together with more recent kitchens, provided oil to the present‐day accumulations. This history involved long‐distance migration and remigration.     

THE VENEZUELAN HYDROCARBON HABITAT, PART 1: TECTONICS, STRUCTURE, PALAEOGEOGRAPHY AND SOURCE ROCKS

Venezuela forms part of an important hydrocarbon province, defined by the presence of prolific Cretaceous source rocks, which extends across northern South America. By early 1997, the country had produced 53 billion barrels of oil. Reserves are estimated to total 73 billion barrels of oil and 146 TCF of gas with 250 billion barrels recoverable in the Heavy Oil Belt. Most reserves are located within the intermontane Maracaibo and foreland Barinas‐Apure and Eastern Venezuela Basinx They correspond to more than 1.5 trillion BOE originally in place. The province's hydrocarbon history began with a broad passive margin over which the sea transgressed throughout much of the Cretaceous. Limestones and shales followed basal sands and included rich source rocks. Convergence between the distal part of the area and the Caribbean Plate created an active margin that migrated southwards, so that flysch and wildflysch followed the transgressive facies. The process culminated in Lute Cretaceous to Middle Eocene orogeny with the emplacement of southward‐vergent nappes and the development of northward‐deepening foredeeps. Flysch and wildflysch formed in the north while important deltaic—paralic reservoir sands accumulated in the south. Major phases of hydrocarbon generation from Jurassic‐Cretaceous source rocks occurred across the entire margin of northern South America during the orogeny. They are recorded by Jurassic ‐ Middle Cretaceous graphitic marbles, schists and quartzites (metamorphosed, organic limestones and shales and oil‐bearing sandstones) in the Coastal and Northern Ranges of Venezuela and Trinidad. They probably charged giant fault and stratigraphic traps analogous to today's Oficina‐Temblador and Heavy Oil Belt accumulations. From Late Eocene to Recent times, transpressive interaction between northern South America and neighbouring parts of the Caribbean and the Pacific inverted Mesozoic extensional systems below the remaining passive margin. The area became subdivided into a series of intermontane, foreland and pull‐apart basins bounded by transpressional uplifts, the latter sufering considerable shortening and strike‐slip displacement. Sedimentation progressed from deep marine to deltaic and molassic facies, providing reservoir sands and local source rocks. Inverted faults and foreland flexuring and interplay between structuration and sedimentation produced abundant structural and stratigraphic traps. Hydrocarbons from earlier accumulations suffered further maturation in place, remigrated to younger traps or escaped to the surface. Further hydrocarbon generation, involving Upper Cretaceous source rocks, occurred in local foredeep kitchens. Minor contributions also came from Tertiary source rocks.     

中东扎格罗斯盆地构造演化与油气分布

扎格罗斯盆地是中东地区重要的含油气盆地之一,已探明储量巨大。通过区域构造演化、盆地构造划分、油气分布特征和油气成藏主控因素研究,认为扎格罗斯盆地由被动陆缘盆地演化而成现今的前陆盆地,经历了早古生代克拉通—弧后伸展阶段、晚古生代弧后伸展阶段、中生代被动陆缘盆地阶段和晚中生代—新生代前陆盆地演化阶段。扎格罗斯山前缘断裂带和高扎格罗斯断裂带将盆地自西南向东北划分为前渊带、简单褶皱带和山前冲断带等3个构造带。扎格罗斯盆地前渊带以油田为主,简单褶皱带以气田为主,山前冲断带挤压构造变形强烈,油气难以保存。下白垩统Kazhdumi组烃源岩为中—新生界储层的主要油源,志留系Gahkum组泥页岩为古生界储层的主要气源;新生界碳酸盐岩为主力储层,其次是白垩系Sarvak组和上二叠统Dalan组碳酸盐岩;前渊带以蒸发岩和泥页岩盖层为主,简单褶皱带则以泥页岩盖层为主。背斜构造和盖层类型为油气成藏的主要控制因素。     

南亚地区油气地质综合研究与区域优选

南亚地区经历冈瓦纳陆内裂陷、冈瓦纳大陆破裂与被动陆缘演化和印度板块与欧亚板块碰撞阶段,形成四大类沉积盆地,包括周缘前陆盆地、被动大陆边缘盆地、大陆裂谷盆地和克拉通盆地。含油气盆地主要分布在印度大陆的东缘和西缘,具有良好的油气地质条件,在层位上集中分布在古近系、新近系和白垩系。盆地类型与演化决定了油气富集规模和时代,有效烃源岩分布控制了油气田的平面分布,储盖组合控制了油气的纵向分布。根据盆地类型和规模、盆地石油地质条件、资源总量和盆地勘探程度等指标对南亚地区沉积盆地进行综合评价,优选出Bombay盆地、Indus盆地、Krishna—Godavari盆地、Bengal盆地、Assam盆地、Cambay盆地、Cauvery盆地、Potwar盆地等有利沉积盆地。     

印度河盆地含油气系统特征与成藏模式

印度河盆地是巴基斯坦最大的沉积盆地，油气资源丰富，油气主要聚集在白垩系-下第三系含油气系统中，以气为主。下白垩统Sembar组海相页岩是主要烃源岩，始新统Sui Main石灰岩和下白垩统下Goru组砂岩是盆地内的两套主要储集层，发育岩性、断块、断鼻和背斜等各类圈闭。油气成藏分为两期，早油晚气，早期形成了盆地南部巴丁地区的白垩纪被动裂谷断块油藏，晚期形成始新世石灰岩礁体岩性气藏。研究结果认为：盆地南部印度河三角洲入海处以及邻近海上区域和中西部褶皱带、前渊带是该区下一步寻找油气的主要目标靶区。     

天山南北前陆冲断带油气地质条件对比及有利勘探领域分析

天山造山带南北两侧分布着库车和准噶尔南缘两个中、新生代前陆冲断带。天山造山带的形成与演化对于其两侧盆地的展布、基底性质、沉积盖层的规模、盆地整体结构特征、后期破坏等具有重要的影响和控制作用。在同一区域构造应力场的作用下,库车前陆冲断带和准噶尔盆地南缘地区构造演化和石油地质条件均表现出许多相似的特征,两者皆发育多套成熟烃源岩,叠置了多套优质储盖组合,发育多种类型的圈闭,生储盖条件配套良好,具备形成大型油气田的物质基础。     

准噶尔盆地隐蔽油气藏类型及有利勘探区带

针对准噶尔盆地隐蔽油气藏勘探潜力巨大但成藏规律非常复杂的情况,在回顾其隐蔽油气藏勘探历程基础上,把已发现的隐蔽油气藏划分为岩性类、地层类、复合类和(准)连续型4大类及17个亚类。其成藏特点为:多沉积体系控制;多圈闭类型展布、构造—岩性—地层复合;多层系含油气;多期充注、多期成藏;多成藏组合型式。隐蔽油气藏有利勘探区带为盆地西缘车排子斜坡带沙湾组成藏组合、车—莫古隆起周缘侏罗系成藏组合、准噶尔盆地石炭系成藏组合和北天山山前坳陷深层致密砂岩侏罗系成藏组合。     

准噶尔盆地油气富集规律

准噶尔盆地是一个"满盆"含油、全层系多层组含油、油气资源丰富的大型沉积盆地.它是在前寒武系结晶基底与前石炭系褶皱基底基础上,经历了晚石炭世-中三叠世前陆盆地阶段、晚三叠世-中侏罗世早期(J₂x)弱伸展拗陷盆地阶段、中侏罗世晚期(J₂t)-白垩纪压扭盆地阶段与新生代前陆盆地阶段的演化历史.4个构造发展阶段不同类型的原型盆地的叠合,形成了南厚北浅的楔形地质结构,决定了油气聚集的基本面貌;不同时期、不同性质的古隆起纵横叠置,制约着相应地质时期油气运聚的基本格局.在垂向上,以上三叠统白碱滩组泥岩、下白垩统吐谷鲁群泥岩与广泛分布的异常压力封隔层为界可将盆地划分为C-T₂,T₃-J₁s,J₂-K₁与K₂-N-4个各具特色的成藏区间;油气沿断裂的垂向运移与异常高压流体系统的幕式突破,导致了以垂向运移为主导的运聚模式,多源、多期油气混合成藏.现有油气田的分布及勘探趋势表明4个NNE向基底断裂带为油气优势运移通道,沿着它们形成了4个油气富集的黄金带.这些基底断裂与盖层断裂之间的耦合方式是制约形成油气田及导致含油气丰度差异的关键条件.准噶尔盆地侏罗系-白垩系与二叠系-三叠系分别发育"远源、缓坡、次生"与"近源、陡坡、原生"两种典型的断裂-岩性体油气藏类型,断裂与岩性体(砂体、砂砾岩、砾岩体等)的有机组合部位是油气富集的主要场所.侏罗系-白垩系的油气主要富集在NE、NEE向压扭性构造带上,它们是腹部地区下一步勘探的主要方向.