Late Mesozoic magmatism and Cenozoic tectonic deformations of the Barents Sea continental margin: Effect on hydrocarbon potential distribution

The paper is focused on the two tectonic-geodynamic factors that made the most appreciable contribution to the transformation of the lithospheric and hydrocarbon potential distribution at the Barents Sea continental margin: Jurassic-Cretaceous basaltic magmatism and the Cenozoic tectonic deformations. The manifestations of Jurassic-Cretaceous basaltic magmatism in the sedimentary cover of the Barents Sea continental margin have been recorded using geological and geophysical techniques. Anomalous seismic units related to basaltic sills hosted in terrigenous sequences are traced in plan view as a tongue from Franz Josef Land Archipelago far to the south along the East Barents Trough System close to its depocentral zone with the transformed thinned Earth’s crust. The Barents Sea igneous province has been contoured. The results of seismic stratigraphy analysis and timing of basaltic rock occurrences indicate with a high probability that the local structures of the hydrocarbon (HC) fields and the Stockman-Lunin Saddle proper were formed and grew almost synchronously with intrusive magmatic activity. The second, no less significant multitectonic stress factor is largely related to the Cenozoic stage of evolution, when the development of oceanic basins was inseparably linked with the Barents Sea margin. The petrophysical properties of rocks from the insular and continental peripheries of the Barents Sea shelf are substantially distinct as evidence for intensification of tectonic processes in the northwestern margin segment. These distinctions are directly reflected in HC potential distribution.     

非洲地区盆地演化与油气分布

非洲地区盆地整体勘探程度较低,待发现资源量大,是当前油气勘探开发的热点地区之一。非洲板块在显生宙主要经历了冈瓦纳大陆形成、整体运动和裂解3个构造演化阶段,形成多种不同类型的盆地。通过板块构造演化和原型盆地研究及石油地质综合分析,明确了不同类型盆地的构造特征与油气富集规律。北非克拉通边缘盆地形成于古生代早期,受海西运动影响,油气主要富集在挤压背景下形成的大型穹隆构造之中,以古生界含油气系统为主;北非边缘裂谷盆地海西运动之后普遍经历了裂谷和沉降,裂谷期各盆地沉降幅度和沉降中心的差异导致了油气成藏模式和资源潜力的差异;东、西非被动陆缘盆地形成于中生代潘吉亚大陆的解体、大西洋和印度洋张裂的过程中,西非被动陆缘盆地普遍发育含盐地层,形成盐上和盐下两套含油气系统,东非被动陆缘盆地结构差异较大,油气分布主要受盆地结构控制;中西非裂谷系是经历早白垩世、晚白垩世和古近纪3期裂谷作用而形成的陆内裂谷盆地,受晚白垩世非洲板块与欧亚板块碰撞的影响,近东西向展布盆地抬升剧烈,油气主要富集在下白垩统,北西南东向盆地受影响较弱,油气主要富集在上白垩统和古近系之中;新生代东非裂谷系盆地和红海盆地形成时间相对较晚,以新生界含油气系统为主,新生代三角洲盆地中油气分布主要受三角洲砂(扇)体展布和盆地结构所控制。     

The effect of Meso-Cenozoic tectonic processes on the formation of Upper Jurassic and Cretaceous hydrocarbon pools in the north of the Aleksandrov arch (West Siberia)

The effect of tectonic processes on the petroleum potential of the Upper Jurassic and Cretaceous sediments is estimated by the example of the deposits in the north of the Aleksandrov arch. The formation history of the structures bearing Upper Jurassic and Cretaceous hydrocarbon (HC) pools is discussed.The results obtained lead to the conclusion that anticlinal traps complicated by faults cutting the Meso-Cenozoic sedimentary cover are the most promising for the formation of large HC pools in Cretaceous sand reservoirs. These traps serve as channels for HC migration from the oil-producing rocks of the Bazhenovo Formation into the overlying reservoirs. In the Upper Jurassic sediments, anticlinal traps free from Cenozoic faults are the most promising for HC accumulation. These conclusions are confirmed by a number of examples.     

西非被动大陆边缘含油气盐盆地构造背景及油气地质特征分析

西非被动边缘含油气盐盆地包括西非安哥拉—喀麦隆段的加蓬盆地、下刚果盆地、宽扎盆地等。认为这些盐盆地从构造、沉积相、油气分布上都具有垂向上的分段性。盆地演化受控于石炭纪末泛大陆裂解及随后南大西洋的张开。盆地演化划分为前裂谷阶段(J3前)、同裂谷阶段(J3—K1)、过渡阶段(K1)和后裂谷阶段(K2—Q)。由于Tristan热点活动以及热带干旱气候的相互作用,过渡阶段发育厚层阿普特阶盐层,将盆地分为盐上、盐下两套油气系统,控制了油气纵向上的分布。盐盆地以上侏罗统—下白垩统特富湖相Ⅰ型烃源岩、森诺曼阶—赛诺统缺氧环境下形成的Ⅱ型海相烃源岩为主要源岩;大型深水浊积扇体为储层,油气通过同生断层及盐窗等疏导通道运聚至构造圈闭、盐层顺层滑脱引起的拱张圈闭以及一些岩性圈闭中,这些有利的成藏条件相匹配形成了巨大规模油田。     

鄂尔多斯盆地中生界油气成藏与构造运动的关系

鄂尔多斯盆地是中国著名的大型中生代含油气盆地,上三叠统延长组和侏罗系延安组为盆地主要含油层系,该含油层系经历了印支、燕山和喜山三期大的构造运动。通过中、新生代不同地质历史时期应力场分析以及构造热事件研究,结合裂缝性质、裂缝方位及裂缝中包裹体特征等,讨论了中生界油气成藏与构造运动的关系。研究认为盆地主要发育E—W向、NNE向和NE向三组区域性裂缝。其中,弱充填的NE向剪裂缝为印支期S—N向挤压环境下形成的剪裂缝,或基底断裂形成的诱导张裂缝;近E—W向展布的弱充填裂缝为燕山期NW—SE挤压环境下形成的剪切裂缝;强烈充填的NNE向张裂缝形成于喜山期NNW—SSE拉张环境。盆地中、新生代地层所经历的每一期构造运动都对盆内油气的运移和聚集起控制作用。印支运动使得盆地沉积了中生界最为重要的一套烃源岩;燕山运动产生的构造热事件使烃源岩达到了生排烃高峰期,使得油气成藏大多定型于燕山期;喜山运动使油气进行大规模的运移和调整,从而使中生界上部油气的分布与基底断裂带走向相吻合。中、新生代这三期构造运动对鄂尔多斯盆地发展和油气成藏产生了重要影响。     

中国海相盆地原型-改造分析与油气有序聚集模式

中国三大海相盆地原型及对油气形成原始物质条件的控制,古生代多次构造运动和中新生代差异性迭加改造对海相碳酸盐岩层系油气成藏、富集的控制作用,以及复杂构造区及超深层海相油气动态成藏过程与富集规律,是制约海相油气勘探发现的关键科学问题。研究认为,在不同板块构造旋回背景下,中国三大克拉通不同时期盆地原型及其沉积模式存在明显差别,可分为台内坳陷、被动大陆边缘和裂谷(陷)三大组合类型,其中被动大陆边缘可以分为陡坡、缓坡两种类型,形成了海相地层内多种类型的源-储配置关系;显生宙以来几次全球板块构造重组,特别是晚三叠世以来在多板块俯冲会聚构造格局下,三大海相克拉通盆地分别经历了4次迭加改造并形成了相应的陆相盆地原型,形成了多种类型的迭加改造地质结构,包括:山前带冲断-褶皱、差异沉降-隆升、多重滑脱构造、深断裂的走滑活动、构造-岩浆作用形成的相关构造;塔里木台盆区“大埋深、高压力、低地温”条件下的生烃抑制控制了油气分布,液态烃分布深度可以超过10 000 m,加里东中晚期和海西期古构造高部位控制了早期油气的运聚,燕山晚期—喜马拉雅期活动的走滑断裂带控制了晚期高熟油气的富集;四川盆地古隆起、古斜坡控制了原始油气聚集,形成了特殊的古油藏烃源灶,后期深埋裂解产生的油型裂解气成了大中型气田的主要气源,晚白垩世之后大规模褶皱变形和抬升剥蚀造成了盆地内流体压力系统重组再造,按照改造程度将油气聚集保存模式划分为:(1)弱改造型,常规、非常规气可在原位长期保存;(2)中改造型,常规气调整再成藏,页岩气规模富集;(3)强改造型,常规气藏大多遭破坏,部分非常规气藏得以保存。鄂尔多斯盆地奥陶系天然气具有“两源三向”的特征,天然气成藏与不整合面-地层层序界面、岩性-岩相变化密切相关,气藏普遍经历了一次调整过程。     

下刚果-刚果扇盆地沉积-构造演化与油气勘探领域

摘要：下刚果-刚果扇盆地位于西非海岸,因其富含油气,资源潜力大,长期以来一直引起众多研究者的关注。由于该区盐构造发育,变形复杂,盆地不同地区和不同勘探目的层勘探程度并不均衡,如何全面认识和评价盆地油气资源潜力成为指导下步勘探工作的关键。通过盆地沉积-构造演化特征研究,指出下刚果-刚果扇盆地是由下刚果盆地与刚果扇盆地垂向上叠置、平面上复合所形成的叠合复合型含油气盆地,经历了前裂谷期、陆内裂谷期、陆间裂谷期和被动陆缘期等演化阶段;在构造特征分析基础上,综合考虑油气成藏要素和运聚方式等特点,划分出新生界构造-岩性圈闭、盐上白垩系构造圈闭和盐下白垩系等三个油气勘探领域;通过各勘探领域油气成藏特征等的系统分析,指出了盆地东部陆上-浅水地区是勘探盐上白垩系构造圈闭勘探领域和盐下白垩系勘探领域的有利地区,盆地西部深水-超深水地区是勘探新生界构造-岩性圈闭勘探领域的有利地区。     

歧口凹陷复式含油气系统及构造控藏模式

构造层序和沉降史分析表明,歧口凹陷在新生代具有显著的幕式构造-沉积演化特征,经历了古近纪裂陷期和新近纪裂后期二个构造活动期、古近纪的裂陷Ⅰ幕和Ⅱ幕、新近纪的稳定热沉降幕和加速沉降幕四幕构造运动。结合凹陷内部重要的构造转换界面、结构和构造演化特点,以及各阶段构造样式和油气成藏聚集规律,将歧口凹陷划分为四大含油气系统:孔店断陷-潜山型含油气系统(Ek)、歧口陡坡断阶型含油气系统(Es)、歧口缓坡断阶型含油气系统(Es1+Ed)、歧口坳陷型含油气系统(N)。通过构造组合样式和油气聚集关系研究,建立了凹陷内部掀斜断块-地垒潜山和凹陷边缘断阶-古隆起披覆潜山构造控藏模式。     

西藏羌塘盆地的深部结构特征与含油气远景评价

羌塘盆地是目前国内石油勘探的热点地区之一,本文综合研究了羌塘盆地的地球物理、石油地质调查资料及INDEPTH-3深部调查结果,得出:①盆地内烃源层、储集层、盖层及其组合条件很好,局部构造发育,有利于形成和保存油气藏,断裂不会成为致命问题,提出了今后工作的主要目的层上三叠统—中侏罗统组成的中构造层;②对盆地二级、三级构造作了新的划分,否定羌中隆起,提出盆地表层的主要构造方向为北西—南东向,成“三凹三隆”及“一深凹”的地壳结构特征,其中主沉降带内部及其两侧是最有利的找油气远景地带;③本区壳幔之间的相互作用较强,盆地北部火山及热活动多,对油气远景评价有较大影响,而盆地南部沉积厚度大,受深层热影响相对较小,是找油气的更有利地段;④强调查明深部地层物性、油气赋存状况,烃类物质的来源和上下构造符合情况是当务之急,重点是加强点上的调查和评价研究;⑤提出不能轻视伦坡拉陆相古近—新近系盆地找油前景,它可能汇聚有两侧海相地层的油气。     

Fold deformations of the paleozoic basement roof in the Chunkurchak Trough,Kyrgyz Ala-Too Range

A structural–geological study has been performed on the northern slope of the Kyrgyz Ala-Too Range. Deformations of the peneplaned Paleozoic basement surface, structures of granite disintegration, and morphostructural manifestation of Late Cenozoic tectonic movements have been investigated. Based on the location of pre-Paleocene peneplain remnants with the retained weathering mantle partly overlapped by Paleocene–Miocene sedimentary complexes, we have reconstructed the morphology of the folded surface of the Chunkurchak Trough separated from the Chu Basin at the early Miocene. The dome–fold forms, the morphology and arrangement of which are controlled by disintegration of the basement, have been described for the basement surface. It has been established that granites are broken by systems of steeply dipping, fanshaped, and gently dipping faults and fractures. Variously oriented insignificant offsets along slickensides, as well as displacements deduced from the geometry of fracture intersections, are a result of volumetric cataclastic flow of rocks. The tectonic mobility of disintegrated granites, which are abundant in the Paleozoic–Precambrian basement, explains the complexity and scale of tectonic processes initiated by Cenozoic activation. In paleotectonic reconstructions, which take into consideration tectonic flow and the redistribution of basement masses, the estimates of Cenozoic relative rapprochement of the Chu Basin and the Kyrgyz Ala-Too Range decrease substantially to 4–6 km.     

渤海湾盆地构造对含油气系统的控制

渤海湾盆地中每个坳陷构成一个大的成熟烃源岩分布区,加上某些凸起的分割,全盆地可划分出13个含油气系统。地堑和半地堑是新生代的基本构造样式,半地堑内含油气系统沿斜坡向外扩展,地堑中的含油气系统基本上限制在两边界断层之间或稍有扩展。盆地早第三纪经历了3个裂陷期,均发育有烃源岩、储层和局部盖层,形成的含油气系统存在着依次改造相互叠加组合的关系。晚第三纪—第四纪属于后裂陷阶段,发育储层和盖层,对早第三纪形成的含油气系统起着增强和改造的作用。构造迁移规律是由南向北、由西向东,由盆地外围向中央。随之主力烃源岩分布、油气生成与运移和油气藏赋存层位也发生有规律变化。使含油气系统在平面上产生差异。     

柴北缘西段新生代弧形构造带演化历史及成藏过程

本文在钻井和二、三维地震数据精细解释的基础上,详细研究了柴北缘西段晚新生代弧形构造带演化历史和油气成藏过程。认为柴北缘西段是由一系列沿造山带前缘展布的弧形逆冲断裂和褶皱组成的弧形构造带。晚新生代以来的构造演化具有自山前向盆内扩展,东西两侧向中间传播的特点,油气运聚与构造演化过程紧密耦合。各弧形构造带两侧形成时间早,生储盖配置好,且具有古构造背景,是油气运聚的长期指向,应是下一步优先勘探目标。     

南海礼乐盆地新生代构造层序界面特征及油气地质意义

礼乐盆地是中国南海深水领域一个重要的含油气盆地,具有较好的油气资源前景。应用沉积学和层序地层学的原理和方法,结合区域构造演化特征,详细研究了礼乐盆地新生代沉积充填过程中关键构造层序界面(S100、S70、S50)在钻井岩性、测井曲线、古生物及地震剖面上的特征。结果表明,构造层序界面为岩性、电性的突变面,在构造层序界面附近,古生物演化过程中存在标志生物种属和数量的突变。在地震剖面上,构造层序界面是区域性的不整合界面,表现为明显的上超、下超或削截特征。进而详细论述了这3个构造层序界面形成的油气地质意义,具体表现为:(1)反映了关键时期礼乐盆地性质的转化;(2)有利于形成优质储集空间;(3)层序不整合面既是油气横向长距离运移的重要通道,也是礼乐盆地油气藏成藏的关键。     

地物化综合方法寻找隐伏岩体—以广西西大明山隐伏岩体的发现为例

广西西大明山地区是广西重要的整装勘查区之一。区内与岩浆活动密切相关的内生矿床丰富,然而仅在局部地表上发现少量的小型岩脉,区内隐伏岩体的预测研究一直是个热点。文章借助广西大规模地质矿产勘查项目,在成岩成矿理论的指导下,通过对区域地质、地球物理、地球化学及遥感等特征的系统分析,确定了西大明山地区深部隐伏岩体的大致分布范围和埋藏深度。在区内选定了埋藏较浅的隐伏岩体预测靶区,有针对性地采取了高精度的地、物、化等方法圈定隐伏岩体的具体位置,经验证有ZK31901、ZK40004两个钻孔分别在500m和960m以下发现了隐伏的黑云母花岗闪长岩,同时在隐伏岩体上部发现了具有工业价值的罗维钨铋矿床。预测靶区验证钻孔成功发现岩体,不仅为相邻地区的隐伏岩体预测工作提供了典型的范例,而且对西大明山地区成矿系统、矿床成因的研究乃至找矿勘查工作具有重要意义。     

龙门山北段矿山梁构造解析及其油气勘探

矿山梁构造是龙门山冲断带北段典型的前锋构造之一,经历了晚三叠世和新生代两期构造挤压变形。矿山梁构造几何学上表现为一个双重构造:浅层是一个晚三叠世形成的断层转折褶皱;深层则是在新生代形成的三个逆冲岩片叠置所构成的隐伏堆垛背斜构造。深部构造的发育改造了上覆晚三叠世形成的浅层构造。矿山梁构造的有利勘探部位是深部的隐伏冲断构造,尤其是新生代构造变形中最早形成的构造岩片即岩片1,但该构造能否具有较好的油气潜力则取决于深部构造顶部滑脱层的封堵能力。分析认为新生代形成的隐伏冲断构造是龙门山冲断带前锋带中油气勘探的新领域。     

郯庐断裂带早新生代的活动性质研究

郯庐断裂带是新生代以来中国东部大陆大地构造演化中最重要的构造带之一,对郯庐断裂的认识制约了大型盆地的形成演化的认识及油气资源的评价。本文在野外实地调查的基础上,从郯庐断裂带与地层的穿切关系入手,借助最新的地震反射剖面以及第一手野外资料,判定郯庐断裂带在新生代早期经历了强烈的活动,表现为左旋兼具逆冲的性质。通过分析覆盖在郯庐断裂带之上火山岩中的断裂发育样式和地震反射剖面上的地层覆盖关系,认为中新世以来,相当于渤海湾盆地的东营运动之后,构造应力场发生了变化,郯庐断裂带不再有显著的活动,发育了新的断裂体系。郯庐断裂新生代兼有垂向位移的走滑活动奠定了中国东部古近纪盆地形成、沉积演化和油气资源成藏的基本格局。     

Conditions of Petroleum Geology of the Qiangtang Basin of the Qinghai-Tibet Plateau

The Qinghai-Tibet Plateau located in the Tethyan tectonic domain is the best developed region of Mesozoic and Cenozoic marine sediments in China. The Qiangtang basin is the biggest and relatively stable area of the plateau. Triassic and Jurassic hydrocarbon source rocks are extensively distributed in the basin. There exist good dolomite and organic reef reservoirs and mudstone and evaporite cap rocks, as well as well-developed structural traps in the basin; in addition destroyed petroleum traps have been discovered. Therefore, the conditions of petroleum geology in the Qiangtang basin are excellent     

Structural Characteristics and Formation Dynamics: A Review of the Main Sedimentary Basins in the Continent of China

The formation and evolution of basins in the China continent are closely related to the collages of many blocks and orogenic belts. Based on a large amount of the geological, geophysical, petroleum exploration data and a large number of published research results, the basement constitutions and evolutions of tectonic–sedimentary of sedimentary basins, the main border fault belts and the orogenesis of their peripheries of the basins are analyzed. Especially, the main typical basins in the eight divisions in the continent of China are analyzed in detail, including the Tarim, Ordos, Sichuan, Songliao, Bohai Bay, Junggar, Qiadam and Qiangtang basins. The main five stages of superimposed evolutions processes of basins revealed, which accompanied with the tectonic processes of the Paleo–Asian Ocean, Tethyan and Western Pacific domains. They contained the formations of main Cratons(1850–800 Ma), developments of marine basins(800–386 Ma), developments of Marine–continental transition basins and super mantle plumes(386–252 Ma), amalgamation of China Continent and developments of continental basins(252–205 Ma) and development of the foreland basins in the western and extensional faulted basin in the eastern of China(205–0 Ma). Therefore, large scale marine sedimentary basins existed in the relatively stable continental blocks of the Proterozoic, developed during the Neoproterozoic to Paleozoic, with the property of the intracontinental cratons and peripheral foreland basins, the multistage superimposing and late reformations of basins. The continental basins developed on the weak or preexisting divisional basements, or the remnant and reformed marine basins in the Meso–Cenozoic, are mainly the continental margins, back–arc basins, retroarc foreland basins, intracontinental rifts and pull–apart basins. The styles and intensity deformation containing the faults, folds and the structural architecture of regional unconformities of the basins, responded to the openings, subductions, closures of oceans, the continent–continent collisions and reactivation of orogenies near the basins in different periods. The evolutions of the Tianshan–Mongol–Hinggan, Kunlun–Qilian–Qinling–Dabie–Sulu, Jiangshao–Shiwandashan, Helanshan–Longmengshan, Taihang–Wuling orogenic belts, the Tibet Plateau and the Altun and Tan–Lu Fault belts have importantly influenced on the tectonic–sedimentary developments, mineralization and hydrocarbon reservoir conditions of their adjacent basins in different times. The evolutions of basins also rely on the deep structures of lithosphere and the rheological properties of the mantle. The mosaic and mirroring geological structures of the deep lithosphere reflect the pre–existed divisions and hot mantle upwelling, constrain to the origins and transforms dynamics of the basins. The leading edges of the basin tectonic dynamics will focus on the basin and mountain coupling, reconstruction of the paleotectonic–paleogeography, establishing relationship between the structural deformations of shallow surface to the deep lithosphere or asthenosphere, as well as the restoring proto–basin and depicting residual basin of the Paleozoic basin, the effects of multiple stages of volcanism and paleo–earthquake events in China.     

Yanshanian–Himalayan geodynamic transformation of the northwestern Junggar Basin,southwestern Central Asian Orogenic Belt (CAOB), and its significance for petroleum accumulation

The northwestern Junggar Basin in the southwestern Central Asian Orogenic Belt is a typical petroliferous basin. The widely distributed reservoirs in Jurassic–Cretaceous strata indicate that the region records Yanshanian–Himalayan tectonic activity, which affected the accumulation and distribution of petroleum. The mechanism of this effect, however, has not been fully explored. To fill the knowledge gap, we studied the structural geology and geochemistry of the well-exposed Wuerhe bitumen deposit. Our results indicate that deformation and hydrocarbon accumulation in the northwestern Junggar Basin during the Yanshanian–Himalayan geodynamic transformation involved two main stages. During the Yanshanian orogeny, a high-angle extensional fault system formed in Jurassic–Cretaceous strata at intermediate to shallow depths owing to dextral shear deformation in the orogenic belt. This fault system connected at depth with the Permian–Triassic oil–gas system, resulting in oil ascending to form fault-controlled reservoirs (e.g., a veined bitumen deposit). During the Himalayan orogeny, this fault system was deactivated owing to sinistral shear caused by far-field stress related to uplift of the Tibetan Plateau. This and the reservoir densification caused by cementation formed favorable hydrocarbon preservation and accumulation conditions. Therefore, the secondary oil reservoirs that formed during the Yanshanian–Himalayan tectonic transformation and the primary oil reservoirs that formed during Hercynian–Indosinian orogenies form a total and complex petroleum system comprising conventional and unconventional petroleum reservoirs. This might be a common feature of oil–gas accumulation in the Central Asian Orogenic Belt and highlights the potential for petroleum exploration at intermediate–shallow depths.     

Petroleum Geological Conditions in Qiangtang Basin

PETROLEUM GEOLOGICAL CONDITIONS IN QIANGTANG BASIN