东海陆架和台西南盆地中生界及其油气勘探潜力

东海陆架和台西南盆地中生界业已成为油气勘探的新领域。构造、沉积、有机地化和储集层物性的研究表明 :该区在中生代为主动大陆边缘盆地 ;该区白垩纪岩浆活动比浙闽沿海地区弱且晚 ,对烃源岩的破坏相对较弱 ,有利于油气的生成和保存 ;该区持续的近岸和滨海环境、晚三叠世 (?)—中侏罗世温暖潮湿的古气候条件 ,有利于烃源岩的形成 ;台北坳陷南部的烃源层系为中下侏罗统 ,储集层系为白垩系 ,台西盆地和台西南盆地的侏罗系—白垩系具有类似的生储条件。台北坳陷南部、闽东坳陷北部和台西南盆地为中生界油气勘探的有利远景区     

额济纳旗地区侏罗—白垩纪盆地演化与油气特征

额济纳旗地区侏罗纪以来经历了两期断陷盆地的发育。早—中侏罗世研究区处于一种张扭构造环境之中,晚侏罗世盆地发生明显抬升和反转。白垩纪—早第三纪盆地演化为一个完整的裂谷发育过程,下白垩统是裂谷早期断陷作用的产物,而上白垩统和下第三系则代表裂谷后期热沉降(或区域坳陷)沉积。侏罗纪盆地和白垩纪盆地应属两类不同性质盆地。两期盆地的不同叠置关系控制了本区烃源岩的发育,影响到这一地区坳陷的油气潜力。下白垩统烃源岩为较差—较好烃源岩,中—下侏罗统为好烃源岩。各凹陷的生烃潜力取决于两期生烃洼陷的规模和叠置关系,天草凹陷继承性发育,中—下侏罗统和下白垩统两套烃源岩叠置关系较好,是额济纳旗地区最有远景的凹陷。     

蒙古尼尔金盆地石油地质特征及勘探前景

位于蒙古国中部的尼尔金盆地是一个中生代裂谷盆地，目前仍处于勘探早期。盆地内下白垩统湖相泥岩和纸状页岩具有很强的生油能力，下白垩统的煤系地层及上二叠统-下侏罗统中富含有机质的泥岩和煤层是可能的气源岩；盆地内广泛分布着3套储集层；上侏罗统、下白垩统、上白垩统的泥岩是潜在的盖层；存在多种生储盖组合及远景圈闭类型。通过对石油地质条件的分析，认为尼尔金盆地很可能形成多套含油气层系和多种油气藏类型，推测在盆地中部和南部会有大的油气藏存在。     

准噶尔盆地南缘若干不整合界面的厘定

通过对准噶尔盆地南缘及邻区18条野外地质剖面岩层岩性及产状的分析,识别出下石炭统齐尔古斯套群与上石炭统柳树沟组之间、中二叠统红雁池组与上二叠统泉子街组之间、下三叠统上仓房沟群与中上三叠统小泉沟群之间、中上三叠统小泉沟群与中下侏罗统水西沟群之间、中下侏罗统水西沟群与中侏罗统头屯河组之间、上侏罗统喀拉扎组与下白垩统之间、上白垩统东沟组与古新统紫泥泉子组之间、中新统塔西河组与上新统独山子组之间及上新统独山子组与第四系之间9个区域不整合界面,大多为角度不整合接触关系。测井曲线、地震剖面等地球物理证据及泥岩样品主微量元素、砂岩碎屑成分、碎屑岩微量元素、砂岩重矿物成分等地球化学证据证明了这9个不整合界面的存在,为准确合理划分研究区构造层序及构造阶段、确定研究区不同阶段成盆作用及改造作用提供了依据。图9参31     

准噶尔盆地南缘下组合成藏条件与大油气田勘探前景

准噶尔盆地是一个油气资源丰富的叠合含油气盆地,该盆地南缘下部成藏组合贴近准南主要烃源层--中下侏罗统煤系地层,宽缓大中型构造圈闭多,上侏罗统-下白垩统深部规模有效储集层发育,下白垩统吐谷鲁群厚层湖相泥岩及三叠系、中下侏罗统各层组内部湖湘泥岩盖层条件好。研究结果表明：该区圈闭与规模有效储集层空间发育匹配;圈闭形成时间与主生排烃期时间匹配;白垩系吐谷鲁群区域盖层与中上侏罗统储盖组合匹配,油气资源量大、发现程度低。结论认为：该区具备大油气田成藏条件,具有良好的勘探前景。     

STRATIGRAPHY AND PETROLEUM GEOLOGY OF THE CROATIAN PART OF THE ADRIATIC BASIN

Coastal parts of Croatia are dominated by the SW‐verging Dinaric foldbelt, to the west and SW of which is the Adriatic Basin (the stable foreland). In both areas, the stratigraphic column is dominated by a thick carbonate succession ranging from Carboniferous to Miocene. Four megasequences have been identified: (i) a pre‐platform succession ranging in age from Late Carboniferous (Middle Pennsylvanian: Moscovian) to Early Jurassic (Early Toarcian; Bru?ane and Ba?ke Ostarije Formations); (ii) an Early Jurassic to Late Cretaceous platform megasequence (Mali Alan Formation); (iii) a Paleogene to Neogene post‐platform megasequence (Ra?a Formation); and (iv) a Neogene to Quaternary (Pliocene to Holocene) megasequence (Istra and Ivana Formations). A number of organic‐rich intervals with source rock potential have been identified on‐ and offshore Croatia: Middle and Upper Carboniferous, Upper Permian, Lower and Middle Triassic, Lower and Upper Jurassic, Lower and Upper Cretaceous, Eocene, and Pliocene – Pleistocene. Traps and potential plays have been identified from seismic data in the Dinaric belt and adjacent foreland. Evaporites of Permian, Triassic and Neogene (Messinian) ages form potential regional seals, and carbonates with secondary porosity form potential reservoirs. Oil and gas shows in wells in the Croatian part of the Adriatic Basin have been recorded but no oil accumulations of commercial value have yet been discovered. In the northern Adriatic offshore Croatia, Pliocene hemi‐pelagic marlstones and shales include source rocks which produce commercial volumes of biogenic gas. The gas is reservoired in unconsolidated sands of the Pleistocene Ivana Formation.     

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东海陆架盆地是发育于华夏板块之上的中、新生代叠合盆地，其下地壳性质与浙闽隆起区一致。盆地前第三纪主要发育侏罗—白垩系沉积，沉积岩主要分布于南部的台北坳陷内。中生代构造演化可分为早中生代坳陷盆地发育和晚中生代断陷盆地发育两个阶段，为下坳上断形式的中生代陆相复合盆地。盆地中生界具有形成油气藏的基本地质条件，其中中下侏罗统暗色泥岩及煤层为主要生烃岩系；上白垩统砂岩具较好的储集性能，储集空间以孔隙—裂缝型为主。     

以构造地层学分析中国东部中、新生代构造-沉积特征

根据构造地层学的原理和方法,将中国东部中、新生界划分为六个构造-沉积旋回,认为侏罗纪末幕运动是中、新生代最重要的、具有划分构造发展阶段意义的构造幕,从而把中、新生代构造演化史划分为三叠-侏罗纪、晚白垩世-第三纪两个阶段和早白垩世过渡阶段,并概述了每个阶段的基本构造特征。     

HYDROCARBON POTENTIAL OF MIDDLE JURASSIC COALY AND LACUSTRINE AND UPPER JURASSIC – LOWERMOST CRETACEOUS MARINE SOURCE ROCKS IN THE SØGNE BASIN,NORTH SEA

The Søgne Basin in the Danish‐Norwegian Central Graben is unique in the North Sea because it has been proven to contain commercial volumes of hydrocarbons derived only from Middle Jurassic coaly source rocks. Exploration here relies on the identification of good quality, mature Middle Jurassic coaly and lacustrine source rocks and Upper Jurassic – lowermost Cretaceous marine source rocks. The present study examines source rock data from almost 900 Middle Jurassic and Upper Jurassic – lowermost Cretaceous samples from 21 wells together with 286 vitrinite reflectance data from 14 wells. The kerogen composition and kinetics for bulk petroleum formation of three Middle Jurassic lacustrine samples were also determined. Differences in kerogen composition between the coaly and marine source rocks result in two principal oil windows: (i) the effective oil window for Middle Jurassic coaly strata, located at ～3800 m and spanning at least ～650 m; and (ii) the oil window for Upper Jurassic – lowermost Cretaceous marine mudstones, located at ～3250 m and spanning ～650 m. A possible third oil window may relate to Middle Jurassic lacustrine deposits. Middle Jurassic coaly strata are thermally mature in the southern part of the Søgne Basin and probably also in the north, whereas they are largely immature in the central part of the basin. HI_max values of the Middle Jurassic coals range from ～150–280 mg HC/g TOC indicating that they are gas‐prone to gas/oil‐prone. The overall source rock quality of the Middle Jurassic coaly rocks is fair to good, although a relatively large number of the samples are of poor source rock quality. At the present day, Middle Jurassic oil‐prone or gas/oil‐prone rocks occur in the southern part of the basin and possibly in a narrow zone in the northern part. In the remainder of the basin, these deposits are considered to be gas‐prone or are absent. Wells in the northernmost part of the Søgne Basin / southernmost Steinbit Terrace encountered Middle Jurassic organic–rich lacustrine mudstones with sapropelic kerogen, high HI values reaching 770 mg HC/g TOC and E_a‐distributions characterised by a single dominant E_a‐peak. The presence of lacustrine mudstones is also suggested by a limited number of samples with HI values above 300 mg HC/g TOC in the southern part of the basin; in addition, palynofacies demonstrate a progressive increase in the abundance and areal extent of lacustrine and brackish open water conditions during Callovian times. A regional presence of oil‐prone Middle Jurassic lacustrine source rocks in the Søgne Basin, however, remains speculative. Middle Jurassic kitchen areas may be present in an elongated palaeo‐depression in the northern part of the Søgne Basin and in restricted areas in the south. Upper Jurassic – lowermost Cretaceous mudstones are thermally mature in the central, western and northern parts of the basin; they are immature in the eastern part towards the Coffee Soil Fault, and overmature in the southernmost part. Only a minor proportion of the mudstones have HI values >300 mg HC/g TOC, and the present‐day source rock quality is for the best samples fair to good. In the south and probably also in most of the northern part of the Søgne Basin, the mudstones are most likely gas‐prone, whereas they may be gas/oil‐prone in the central part of the basin. A narrow elongated zone in the northern part of the basin may be oil‐prone. The marine mudstones are, however, volumetrically more significant than the Middle Jurassic strata. Possible Upper Jurassic – lowermost Cretaceous kitchen areas are today restricted to the central Søgne Basin and the elongated palaeo‐depression in the north.     

下扬子区中—新生代变格构造运动

下扬子区在中、晚三叠世—早、中侏罗世,晚侏罗世—早白垩世和晚白垩世―第三纪时期,发生了以特提斯洋与太平洋板块联合作用所导致的3期变格构造运动。一方面极大地使下扬子区古生代盆地发生了基底拆离式递进变形改造;另一方面又在下扬子区形成了上三叠统―中、下侏罗统的前渊盆地,以及由大型断裂带的平移走滑构造所形成的上侏罗统—下白垩统火山碎屑岩拉分盆地,呈“多米诺式”排列的上白垩统—第三系半地堑盆地则是岩石圈伸展拆离构造所形成的拉张盆地。3期变格运动促使了油气的形成与再分配聚集。      

合肥盆地速度场特征

通过地震测井及地震叠前深度偏移处理,合肥盆地沉积岩速度场表现出复杂的空间差异性。总体上看,埋深及岩性是控制速度的主要因素,中、新生界以侏罗系特别是下侏罗统的层速度高,普遍达5000～6000m/s以上,反映其岩性致密及埋深较大;以中、上白垩统及第三系层速度较低,成为合肥盆地油气勘探的主要目的层。侏罗系下伏的古生界—上元古界遭受了印支期强烈的冲断叠覆改造,其速度场异常复杂。综合分析认为,大桥凹陷是合肥盆地油气勘探的主要有利地区,以勘探白垩系低幅度背斜—半背斜圈闭及岩性圈闭天然气藏为主,因此,进行深入细致的地震速度分析处理及地质-地球物理一体化综合解释、有效地识别这些圈闭就成为当前勘探工作的关键。      

中扬子区与上、下扬子区油气地质条件的对比分析

中扬子区在震旦纪—志留纪期间,其总体构造格局是南接南华地槽,北邻秦岭地槽,由于南北各有一个被动大陆边缘,有利于油气的生成、运移和聚集。泥盆纪至中三叠世为一套地台型沉积,亦具有形成油气的良好地质条件。本区晚元古代至古生代的沉积、构造特点近于上扬子区,但较上扬子区活跃;而中新生代近于下扬子区,较下扬子区活动强度要弱一些。中扬子区这种"动、静相宜"的大地构造特征,为油气的生成、运移和聚集提供了良好的环境。      

柴达木盆地北缘地区中生代盆地性质探讨

柴达木盆地北缘地区在侏罗纪主要受伸展构造体制控制,发育一系列规模较小的箕状断陷盆地。断陷中的中、下侏罗统沉积作用明显受断层控制,为断陷盆地。上侏罗统的沉积作用基本不受断层控制,为坳陷盆地。在白垩纪,柴北缘地区主要受挤压构造体制控制,在祁连山山前形成断层传播褶皱,沉积作用受挤压作用过程中形成的断层传播褶皱控制,为压性盆地。     

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.     

蒙南盆地群石油地质条件评价

蒙南盆地群位于内蒙古中西部,由大小不等的10多个盆地组成。与油气有关的沉积地层主要是侏罗系和白垩系。经野外露头剖面和钻井岩性分析,下、中侏罗统五当沟组、厂汉沟组和下白垩统固阳组发育深湖半深湖相泥(页)岩、碳质泥岩和泥灰岩,是区内主要的烃源岩。烃源岩已进入成熟阶段,处于生油高峰期。侏罗系白垩系发育多套扇三角洲、分流河道以及三角洲前缘砂体,是较好的储集砂体。其中,侏罗系储集砂体的孔渗条件较差,白垩系砂体的孔渗条件较好。从整体上看,侏罗白垩系不仅具有下生、中储、上盖的组合型式,而且各层序亦具有自生、自储、自盖的组合型式。综合分析后,认为武川、桑根达来盆地为勘探最有利地区,三道沟、旗下营、乌兰花、固阳等盆地居次。     

THE MESOZOIC SEQUENCE IN SOUTH-WEST IRAN AND ADJACENT AREAS

New outcrop and subsurface data from SW Iran have permitted a review of the stratigraphy of the area to the SW of the Zagros Crush Zone and a comparison with neighbouing areas. The Triassic sequence consists mainly of an evaporite and dolomite sequence in the coastal areas of the Persian Gulf which is the extension of the evaporite basin of Saudi Arabia and Iraq. Towards the high Zagros in the northeast, the evaporites are replaced by dolomites. Two unconformities are found at the base and top of the Triassic. The Jurassic in Fars and eastern Khuzestan consists of an argillaceous interval representing early Liassic time, overlain by a thick development of neritic carbonates of early to late Jurassic age. An evaporite unit developed in the upper Jurassic is present in coastal/subcoastal areas of Fars and eastern Khuzestan and is the north-eastwards extension of Hith Anhydrite of Saudi Arabia. The end of the Jurassic was marked by uplift and erosion, giving rise to an unconformity over a large area. In western Khuzestan and Lurestan, the Lower Jurassic is a sequence of alternating evaporites and dolomites. The Middle Jurassic is represented by deeper water bituminous shales and argillaceous limestones of the Sargelu Formation, which is cut by a regional unconformity in this area. The Upper Jurassic is represented by the evaporites of the Gotnia Formation which is terminated by the possible Upper Jurassic unconformity. The Jurassic sequence of this area can be correlated well with that of eastern Iraq. In the high Zagros area to the south of the Crush Zone, the Jurassic consists of a thick development of shelf carbonates with no evaporites. The Cretaceous System in SW Iran is divided into Lower (Neocomian-Aptian), Middle (Albian-Turonian) and Upper (Coniacian-Maastrichtian). The Lower Cretaceous is mainly made up of two shelf carbonate unit separated by shales in Fars and eastern Khuzestan. Towards Lurestan, the carbonates pass into deeper water black shales and limestones with radiolaria. The top of the Lower Cretaceous is marked by a regional unconformity in Fars and the Persian Gulf area. The Middle Cretaceous began with a transgression forming the shales and limestones of the Kazhdumi Formation which was followed by a shallowing of the sea and the deposition of Cenomanian and Turonian shelf carbonates over the entire area of Fars and Khuzestan. The Lurestan basin retreated northwards and northwestwards and covered only central Lurestan during Albian- Turonian time, with the deposition of dark grey to black shales and pelagic limestones of the Garau and the Oligostegina bearing limestones of the Sarvak Formation. At least two pronounced regional unconformities have been recognized, between the Cenomanian and Turonian and between the Turonian and Coniacian. The Upper Cretaceous is represented by limestones at the base and a transgressive shale unit at the top, which is terminated by a regional unconformity at the Cretaceous/Tertiary boundary. Isopach and lithofacies maps of various units and correlations of outcrop and subsurface sections indicate several important unconformities and facies changes in SW Iran during the course of the Mesozoic. The general stratigraphy of the region shows similarities to the Mesozoic sequence of Iraq and Saudi Arabia, with a gradual facies change from carbonates to sandstone towards Saudi Arabia. This change is most evident in the Upper Triassic and in the Barremian-Cenomanian. The Upper Cretaceous sequence of SW Iran changes from mainly argillaceous sediments of deeper marine environment into carbonates of shallow water origin towards Saudi Arabia. The correlation of the Mesozoic sequence of SW Iran with those to the northeast of the Zagros Crush Zone indicates a rather abrupt change from the Upper Triassic onwards.     

HYDROCARBON POTENTIAL OF THE INTRACRATONIC OGADEN BASIN, SE ETHIOPIA

The intracratonic Ogaden Basin, which covers one-third of the Democratic Republic of Ethiopia, developed in response to a tri-radial rift system which was active during Late Palaeozoic to Mesozoic times. Thick Permian to Cretaceous sequences, which principally occur in the SW and central parts of the basin, have proved petroleum potential. Reservoir rocks are mainly Permian to Lower Jurassic sandstones (the Calub and Adigrat Formations), and Callovian limestones (the Upper Hamanlei Formation). Source rocks are organic-rich Permian, Lower Jurassic and Callovian-Oxfordian lacustrine and marine shales.
This paper reviews the petroleum geology of the Ogaden Basin and assesses potential exploration targets. Successful exploration can be expected in view of the recent discovery of the Calub gas and gas/condensate field, and the occurrence of significant shows in the centre of the basin together with seeps along the margin.     

鄂尔多斯盆地及其邻区关键构造变革期次及其特征

鄂尔多斯盆地为典型的克拉通内盆地,油、气、煤、盐、铀等矿产资源丰富。研究构造运动的期次、序列与性质将为揭示克拉通盆地的成因与演化过程奠定基础,同时也将为探讨多种能源、矿产资源赋存的内在机制提供依据。基于近年来的高精度区域反射地震剖面和深井资料,结合周缘地质露头分析,通过厘定鄂尔多斯盆地的关键构造变革时期,建立了盆地演化的时-空框架。研究表明,鄂尔多斯盆地由下至上发育10个区域不整合面,分别为长城系、蓟县系、震旦系、寒武系、奥陶系、石炭系、三叠系、侏罗系、白垩系和第四系底界不整合面;盆地发育中元古界、寒武系-奥陶系、上石炭统-三叠系、侏罗系、下白垩统和新生界6个构造-地层层序。鄂尔多斯盆地的形成与演化受控于周缘板块构造作用,经历了中元古代早-中期大陆裂解、寒武纪-中奥陶世被动大陆边缘、晚奥陶世主动大陆边缘形成与碰撞造山、晚石炭世-二叠纪末期周缘裂解、中生代早期大型陆内坳陷、中生代中-晚期陆内前陆盆地和新生代周缘断陷等演化过程。鄂尔多斯盆地岩石圈深部的构造作用相对活跃,盆地内部发育中奥陶世、中-晚三叠世、早白垩世与晚中新世4期中酸性、中基性火山活动,其中,早白垩世晚期的火山活动强烈。结合周缘板块构造事件、盆内岩浆活动和盆地沉降-隆升过程分析,鄂尔多斯盆地经历了新元古代、晚奥陶世、中-晚三叠世、晚侏罗世-早白垩世、新生代5个关键构造变革期,这些构造变革期控制了盆地的构造演化和地质结构,对鄂尔多斯盆地的油气分布产生了深远影响。     

准噶尔盆地演化历史与含油气性探讨

准噶尔盆地的发展,经历了晚古生代弧后盆地阶段,晚二叠世至侏罗纪的残余弧后盆地阶段以及其后的远源碰撞山间盆地阶段。它是一个由多期原型盆地叠置的继承性盆地,为烃源岩的生成演化提供了有利的构造环境。各时代各类圈闭发育,含油气远景良好。     

秦岭—大别造山带北侧盆地序列及油气前景

秦岭—大别造山带北侧存在多个盆地,其中有些盆地中已有一定的油气显示。近年来地质、地球化学研究成果表明,秦岭—大别造山带北侧主要发育6个世代的盆地序列,分别是:1)被动大陆边缘盆地(-C₁—O₂);2)弧后盆地(O₂—C₁);3)残余盆地(C₂—T₂),其中可分为残余盆地第1阶段(C₂—P₁2)和残余盆地第2阶段(P₁2—T₂);4)陆内前陆盆地(T₃—J);5)张扭性盆地(J₃—K₁);6)断—拗盆地(K₂—E)。秦岭—大别造山带北侧盆地发育6套烃源岩层系,分别是古近系、下白垩统、下侏罗统、上三叠统、石炭—二叠系和下古生界,并进行了相关烃源岩层系的成藏特征分析。东秦岭—大别山北侧主要勘探层系第一位的是石炭—二叠系,第二位是下白垩统,第三位是上三叠统,第四位是古近系,而中—下侏罗统及下古生界可列为第五位。建议勘探选区是一类盆地为周口盆地、济源盆地和洛—伊盆地。有利区带是谭庄—沈丘凹陷、倪丘集凹陷、襄城凹陷、舞阳凹陷、孟县—温县凹陷和洛阳凹陷。