西西伯利亚巨型含油气盆地中生界有机质的破坏因素

西西伯利亚巨型含油气盆地侏罗系有机质的成熟度取决于地层的埋深和这一时期它所经受的最高温度。沉积盖层中的温度分布与古生代基底局部断块的褶皱时代、深大断裂的形成时间，以及岩浆岩的成分、侵入时间有关。这些控制着温度场和西西伯利亚沉积盖层中有机质成熟度的因素是全球性的。划分出了3种基本的断块类型，它们与根据基底固结时代而划分的构造区划相对应。第1类断块与贝加尔褶皱带的断块相一致；第2类断块与海西运动期、加里东运动期的断块相一致；第3类断块为巨型盆地基底中的三叠纪裂谷，大型花岗岩体、某些流体输导断裂与此相一致。     

THE SIGNIFICANCE OF STRIKE-SLIP FAULTING IN THE BASEMENT OF THE ZAGROS FOLD AND THRUST BELT

Lateral offsets in the pattern of seismicity along the Zagros fold and thrust belt indicate that transverse faults segmenting the Arabian basement are active deep‐seated strike‐slip faults. The dominant NW‐SE trending features of the belt have undergone repeated horizontal displacements along these transverse faults. These reactivated basement faults, which are inherited from the Pan‐African construction phase, controlled both deposition of the Phanerozoic cover before Tertiary‐Recent deformation of the Zagros and probably the entrapment of hydrocarbons on the NE margin of Arabia and in the Zagros area. We have used observations of faulting recognized on Landsat satellite images, in conjunction with the spatial distribution of earthquakes and their focal mechanism solutions, to infer a tectonic model for the Zagros basement. Deformation in the NW Zagros appears to be concentrated on basement thrusts and a few widely‐spaced north‐south trending strike‐slip faults which separate major structural segments. In the SE Zagros, two main structural domains can be distinguished. A domain of NNW‐trending right‐lateral faults in the northern part of the SE Zagros implies that fault‐bounded blocks are likely to have rotated anticlockwise about vertical axes relative to both Arabia and Central Iran. In contrast, the predominance of NNE‐trending left‐lateral faults in the southern part of the SE Zagros implies that fault‐bounded blocks may have rotated clockwise about vertical axes. We propose a tectonic model in which crustal blocks bounded by strike‐slip faults in a zone of simple shear rotate about vertical axes relative to both Arabia and Central Iran. The presence of domains of strike‐slip and thrust faulting in the Zagros basement suggest that some of the convergence between Arabia and Central Iran is accommodated by rotation and possible lateral movement of crust along the belt by strike‐slip faults, as well as by obvious crustal shortening and thickening along thrust faults.     

PETROLEUM GEOLOGY OF THE NOGAL BASIN AND SURROUNDING AREA,NORTHERN SOMALIA,PART 2: HYDROCARBON POTENTIAL

Seismic reflection profiles and well data show that the Nogal Basin, northern Somalia, has a structure and stratigraphy suitable for the generation and trapping of hydrocarbons. However, the data suggest that the Upper Jurassic Bihendula Group, which is the main source rock elsewhere in northern Somalia, is largely absent from the basin or is present only in the western part. The high geothermal gradient (～35–49 °C/km) and rapid increase of vitrinite reflectance with depth in the Upper Cretaceous succession indicate that the Gumburo Formation shales may locally have reached oil window maturity close to plutonic bodies. The Gumburo and Jesomma Formations include high quality reservoir sandstones and are sealed by transgressive mudstones and carbonates. ID petroleum systems modelling was performed at wells Nogal‐1 and Kalis‐1, with 2D modelling along seismic lines CS‐155 and CS‐229 which pass through the wells. Two source rock models (Bihendula and lower Gumburo) were considered at the Nogal‐1 well because the well did not penetrate the sequences below the Gumburo Formation. The two models generated significant hydrocarbon accumulations in tilted fault blocks within the Adigrat and Gumburo Formations. However, the model along the Kalis‐1 well generated only negligible volumes of hydrocarbons, implying that the hydrocarbon potential is higher in the western part of the Nogal Basin than in the east. Potential traps in the basin are rotated fault blocks and roll‐over anticlines which were mainly developed during Oligocene–Miocene rifting. The main exploration risks in the basin are the lack of the Upper Jurassic source and reservoirs rocks, and the uncertain maturity of the Upper Cretaceous Gumburo and Jesomma shales. In addition, Oligocene‐Miocene rift‐related deformation has resulted in trap breaching and the reactivation of Late Cretaceous faults.     

南鄱阳坳陷油气成藏条件分析

最近几年的区域油气勘探与新资料评价表明：南鄱阳坳陷具有“上张下逆”双层结构的叠合盆地构造背景,晚期伸展沉积的陆相白垩系区域盖层造就了二叠系、三叠系海相-海陆过渡相烃源岩在喜马拉雅期的二次生烃和晚期成藏条件;地处前白垩纪“南北对冲”前缘带的旧夏、二甲村凹陷,二叠系保存状况和白垩系盖层构筑的整体封闭保存条件较好,二叠系龙潭组树皮煤是该区已知的特征性优质煤成油烃源岩;“自生自储型”的龙潭组油气藏是该区其最有勘探前景的油气成藏类型,次为“下生上储型”的白垩系周家店组底部油气藏;而地处“凹中隆”的龙皮构造带则具有浅层油气勘探的现实性,可作为南鄱阳坳陷近期勘探的突破口。     

DISTRIBUTION OF SOURCE ROCKS AND MATURITY MODELLING IN THE NORTHERN CENOZOIC SONG HONG BASIN (GULF OF TONKIN), VIETNAM

The northern offshore part of the Cenozoic Song Hong Basin in the Gulf of Tonkin (East Vietnam Sea) is at an early stage of exploration with only a few wells drilled. Oil to source rock correlation indicates that coals are responsible for the sub‐commercial oil and gas accumulations in sandstones in two of the four wells which have been drilled on faulted anticlines and flower structures. The wells are located in a narrow, structurally inverted zone with a thick predominantly deltaic Miocene succession between the Song Chay and Vinh Ninh/Song Lo fault zones. These faults are splays belonging to the offshore extension of the Red River Fault Zone. Access to a database of 3,500 km of 2D seismic data has allowed a detailed and consistent break‐down of the geological record of the northern part of the basin into chronostratigraphic events which were used as inputs to model the hydrocarbon generation history. In addition, seismic facies mapping, using the internal reflection characteristics of selected seismic sequences, has been applied to predict the lateral distribution of source rock intervals. The results based on Yükler ID basin modelling are presented as profiles and maturity maps. The robustness of the results are analysed by testing different heat flow scenarios and by transfer of the model concept to IES Petromod software to obtain a more acceptable temperature history reconstruction using the Easy%R₀ algorithm. Miocene coals in the wells located in the inverted zone between the fault splays are present in separate intervals. Seismic facies analysis suggests that the upper interval is of limited areal extent. The lower interval, of more widespread occurrence, is presently in the oil and condensate generating zones in deep synclines between inversion ridges. The Yükler modelling indicates, however, that the coaly source rock interval entered the main window prior to formation of traps as a result of Late Miocene inversion. Lacustrine mudstones, similar to the highly oil‐prone Oligocene mudstones and coals which are exposed in the Dong Ho area at the northern margin of the Song Hong Basin and on Bach Long Vi Island in Gulf of Tonkin, are interpreted to be preserved in a system of undrilled NW–SE Paleogene half‐grabens NE of the Song Lo Fault Zone. This is based on the presence of intervals with distinct, continuous, high reflection seismic amplitudes. Considerable overlap exists between the shale‐prone seismic facies and the modelled extent of the present‐day oil and condensate generating zones, suggesting that active source kitchens also exist in this part of the basin. Recently reported oil in a well located onshore (BIO‐STB‐IX) at the margin of the basin, which is sourced mainly from “Dong Ho type” lacustrine mudstones supports the presence of an additional Paleogene sourced petroleum system.     

北海维京地堑Beryl湾中、晚侏罗世高分辨率沉降分析及其意义

在Beryl湾发育南北向、北西向和北东向三组正断层。根据北海维京地堑Beryl湾73口井的高分辨率层序地层学分析和高分辨率沉降分析,阐明中、晚侏罗世沉积和沉降模式,确定应力场的变化及边界断层的连锁对沉积和含油气系统的控制作用。高分辨率(1~2Ma)允许评价不同走向断层随时间的演化。不仅阐明了东舍德兰断层连锁的时间和机侧,而且阐明了对沉积相的控制作用。研究结果表明,在中、晚侏罗世同裂谷期Beryl湾伸展方向发生了45°的顺时针旋转;东舍德兰断层在早、中牛津期由两段连锁为一条统一的断层。     

Overview on the subsurface structure-tectonic controls in the northwest Bahariya,Western Desert,Egypt

A regional structural investigation was done on the northwestern part of Bahariya Oasis, using the potential field maps aided by geo-seismic sections and wells data. The gravity and magnetic maps were reinterpreted in context of geotectonic evolution of the north Western Desert to throw more light on the source of subsurface structures. Several processing methods and filtering techniques were applied to delineate locations, trends and depths of main source structures. Qualitatively, the study indicates that Bahariya horst is the highest in gravity, Sitra platform has the strongest magnetism, whereas Misawage graben is the largest in depth to the basement surface. The results were integrated to construct a tentative tectonic map, which exhibits an older folding in the NW direction intersected by a younger ENE trend, which seems to be crossed by a set of NW-trending faults. The map underlines regional folding in NE-SW trend (Syrian arc), forming four major structural features (Misawage graben, Sitra platform, Bahariya uplift and Dirrut basin), each has distinctive characteristics. The tectonic model suggests two different forces (NNW-compression and ENE-tension) affected the area, forming two main fold trends and five cycles of deformation. The models indicate a rough basement surface with a regional dip regime toward the north, overlain by a sedimentary cover ranges between 1 and 4.5 km in thickness. The basement is generally of acidic composition with some basic intrusions penetrate the boundary faults.     

羌塘盆地三叠系、侏罗系石油地质特征和含油远景评价

羌塘盆地是发育在前泥盆结晶基底和上古生界浅变质褶皱基底之上以中生界海相沉积为主体的复合型残留盆地。它由北羌塘坳陷带、中央隆起带和南羌塘坳陷带3个二级构造单元组成,主要发育三叠系和侏罗系两套生储盖组合。北羌塘坳陷带内,三叠系及侏罗系组合发育良好;中央隆起带内基本没有侏罗系组合,三叠系组合也仅分布于倾伏部位;南羌塘坳陷带内,三叠系组合发育良好,局部范围内也有较好的侏罗系组合。青藏高原的油气勘探实践表明,该区含油远景取决于构造运动的强弱及保存条件的好坏。结合生储盖组合情况,羌塘盆地可分为3类含油气远景区:北羌塘坳陷带有利区、南羌塘坳陷带有利区和中央隆起带次有利区。     

OIL CHARGE HISTORY OF BITUMENS OF DIFFERING MATURITIES IN EXHUMED PALAEOZOIC RESERVOIR ROCKS AT TIANJINGSHAN,NW SICHUAN BASIN,SOUTHERN CHINA

Low‐maturity soft bitumen (or biodegraded heavy oil) and higher maturity solid bitumen are present in Palaeozoic siliciclastics at Tianjingshan in the NW Sichuan Basin, southern China. The origin of these bitumens of variable maturities was investigated. Samples of low‐maturity bitumen from Lower Devonian sandstones and high‐ and low‐maturity bitumen from Upper Cambrian siltstones were analysed to investigate their organic geochemistry and stable isotope compositions. Lower Cambrian and Upper Permian black shales were also investigated to assess their source rock potential, and the burial and maturation history of potential source rocks was modelled using PetroMod. Liquid and gaseous hydrocarbon fluid inclusions in the Devonian sandstones were analysed. Results suggest that both the soft and solid bitumens are derived from crude oil generated by Lower Cambrian organic‐rich black shales. Reservoir rocks at Tianjingshan have experienced two separate oil charge events – in the early‐middle Triassic and early‐middle Jurassic, respectively. The first oil charge was generated by Lower Cambrian black shales in a kitchen area located in the hanging wall of the Tianjingshan fault. The later oil charge was also derived from Lower Cambrian black shales, but the kitchen area was located in the footwall of the fault. Movement on the Tianjingshan fault resulted in progressive burial of the Lower Devonian sandstone reservoir rocks until the end of the middle Triassic, and the “early” charged oil was thermally degraded into high‐maturity solid bitumen. The later‐charged oil was altered into soft bitumen of lower maturiy by biodegradation during uplift of the reservoir after the Jurassic.     

百色盆地东部中三叠统基底灰岩预测

上法灰岩是夹于大套中三叠统碎屑岩中的灰岩透镜体,它是盆地与台地两大相区相变线附近地貌陡变带中的沉积,经剥蚀后残留于基底表面的高部即基岩向斜的核部,形成由向斜构造-地层不整合面-岩性诸因素控制的基岩油气藏,生油层为上始新统那读组,储层为中三叠统上一段,盖层为第三系底部之泥页岩,预计在基岩凸起上二段围限的区域内布钻可获成功。     

吐孜托依拉断裂带的构造特征及找油前景

吐孜托依拉断裂发育于准噶尔盆地东北缘,长达180km。本文依据近几年勘探获得的资料,探讨了断裂带的构造特征与发育简史。从生油及储、聚条件分析,认为找油前景较好。     

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.     

辽河断陷内郯庐断裂的位置及对油区的控制

辽河油田经过十余年勘探,取得了大量的深井和地震资料,经分析研究发现区内前第三系基底在东西方向上分为三块,中间存在两条断裂。本文在论述三块基底差异的基础上,提出郯庐断裂通过辽河断陷内的位置及其平移的性质。东面一条基底断裂是主干断裂,西面的是并列断裂。由于它们的存在及其活动的差异,对下第三系的油区有较明显的控制,因此造成了辽河断陷的东西凹陷的油气富集程度的差异。     

COMPOSITION OF DIAMONDOIDS IN OIL SAMPLES FROM THE ALPINE FORELAND BASIN,AUSTRIA: POTENTIAL AS INDICES OF SOURCE ROCK FACIES,MATURITY AND BIODEGRADATION

Twenty‐seven oil samples from Cretaceous, Eocene and Rupelian reservoir rocks in the Alpine Foreland Basin (Austria) were analysed to evaluate the composition of diamondoid hydrocarbons using gas chromatography – triple quadrupole mass spectrometry. The oils were generated from marly and shaly Oligocene source rocks buried beneath the nappes of the Alpine foldbelt to the south of the study area. Diamondoid hydrocarbons were detected in the saturated fraction of all the analysed oils. A biodegraded oil sample from a shallow reservoir in the NE part of the study area showed an enrichment in diamondoids due to the molecule's high resistance to microbial degradation. Variations in the organic matter type of the source rock facies and differences in maturity are known to influence the composition of diamondoids. However in this study, biomarker‐derived maturity parameters do not show a convincing correlation with diamondoid maturity parameters. Moreover, no cracking trend based on biomarkers and diamondoid concentrations was observed. The results indicate that the composition of diamondoids in oils from the Austrian part of the Alpine Foreland Basin is mainly controlled by heterogeneities in the Lower Oligocene source rocks, including the occurrence of a redeposited source rock succession in the western part of the study area. By contrast, EAI‐1 (the ethyladamantane index) shows a good correlation with various maturity parameters and seems to be independent of source rock facies.     

江汉盆地西南缘油气运移及其成藏模式

对江汉盆地西南缘的油源对比和流体势分析表明,北部地区的原油主要来自梅槐桥—牛头岗洼陷高成熟度烃源岩,南部地区的原油与本地的低成熟度烃源岩具有亲缘关系,中部地区的原油则具有混源特征.该区的油气明显具有运移距离短、近源聚集的特点;其分布与聚集受到断层和圈闭类型等因素的影响.断层活动使上升盘储层与下降盘烃源岩对接,是新生古储型油气藏成藏的关键;断层的封闭性上部要优于下部,控制着油气富集的层位.圈闭类型以断鼻和断块为主,断鼻油气藏主要分布在断层的下降盘,而断块油气藏主要分布在断层的上升盘.根据油气聚集特点和储集层位的差异,将本区的油气藏划分为自生自储、新生古储和下生上储3种成藏模式.     

TECTONOSTRATIGRAPHIC ANALYSIS OF THE UPPER CAMBRIAN – DEVONIAN SEDIMENTARY SUCCESSION IN THE CENTRAL DARLING BASIN,SE AUSTRALIA: AN INTEGRATED INTERPRETATION OF SEISMIC,GRAVITY AND WELL DATA

This paper presents a tectonostratigraphic interpretation based on seismic, gravity and well data of the Upper Cambrian through Devonian sedimentary succession in the central part of the Darling Basin, New South Wales (SE Australia). A composite roughly north‐south trending 2D seismic section through this area, tied to two exploration wells, defines four unconformity‐bound second‐order seismic megasequences. The megasequences are: A, Upper Cambrian – Middle Ordovician (Llanvirnian?); B, uppermost Silurian – Lower Devonian (Emsian); C, upper Lower Devonian – lower Middle Devonian (Givetian); and D, upper Middle Devonian – Upper Devonian (Famennian). The megasequences are bounded by prominent seismic marker horizons which represent phases of regional‐scale orogenic activity. The composite 2D section studied is about 150 km long and traverses from north to south the Pondie Range sub‐basin, the inverted Wilcannia High and the Blantyre sub‐basin. Along the section, the Upper Cambrian to Devonian succession is deformed into a series of large‐scale, fault‐associated anticlines and synclines including the Avon High, an asymmetric anticlinal fold associated with several high‐angle reverse faults. Major faults extend into, and flatten within, the basement. The top‐basement surface is characterized by broad highs and lows which are represented on a gravity map of the study area. The map shows that the Wilcannia High defines the northern margin of the Blantyre sub‐basin and the southern margin of the Pondie Range sub‐basin. These sub‐basins are in general defined by gravity lows. The development of the Blantyre and Pondie Range sub‐basins can be divided into five tectonostratigraphic phases during which there were distinct patterns of fault activity and regional subsidence. These phases are investigated using a restoration model which involves the successive removal of each seismic megasequence in turn, assuming simple vertical shear. The model provides new constraints on the distribution of structural and stratigraphic features which are relevant for future hydrocarbon exploration.     

西藏措勤盆地构造沉积演化及含油气远景

西藏措勤盆地是中生代特提斯构造域的一个大型构造复合盆地,主体位于冈底斯-念青唐古拉板块之上,包括北部坳陷带、中部斜坡带、南部岩浆岩带三个构造沉积单元。中生代盆地演化上经历了初始裂谷(T₃-J₁)、周缘前陆盆地(J₂-J₃)、孤后前陆盆地(K₁-K₂)等阶段。其中,北部坳陷带发育了近万米厚的中生代地层。上三叠统、中上侏罗统巨厚海相沉积地层在接近班公湖-怒江断裂带发生变质作用,但在远离该断裂带的盆地前隆地带仍具有良好的生储盖组合,有条件形成一些超覆油气藏或者与后期冲断褶皱有关的构造岩性油气藏。下白垩统属退积的潮坪-碳酸盐岩台地沉积序列,生、储油层发育,但盖层发育相对较差,有可能在靠近改则-尼玛断裂带附近形成一些与逆冲断层有关的小型油气藏。第三纪以来青藏高原迅速隆升所造成的本地区海水快速退出、海相地层大范围暴露剥蚀是措勤盆地难以形成如波斯湾一样巨型油气田的主要原因。     

THE EFFECT OF BASEMENT FAULTING ON DIAPIRISM

Experimental and natural examples illustrate the influence of sub-salt horizon basement faults on diapirism. In a series of experimental models, viscous diapirs were observed to form above or close to basement faults. In all the models, basement faults initiated a half-graben, where thicker overburden units enhanced differential loading on an underlying buoyant layer. The buoyant material flowed updip to the low-pressure zones in the uplifted block, and updip along the tilted upper boundary of the hanging-wall. Basement faulting extended the overburden, and provided the space through which the buoyant layer could rise. Subsidence and faulting of overburden layers allowed diapirism along the faulted zones. In all cases, the deformation in the overburden was accommodated within a wider zone of faulting than the discrete basement fault which initiated the deformation. Differential compaction enhances differential loading and accumulation of thicker overburden on the downthrown sides of basement faults.
Seismic profiles from the Danish Basin, Dutch Central Graben, Gulf of Mexico and North Sea show that diapirs are spatially associated with basement faults. However, model results show that diapirs triggered by basement faults are not necessarily located directly above the faults.
Basement faults extend the cover sequences. If detached from the cover by a ductile layer, thick-skinned extension is accompanied by thin-skinned extension and decoupling of the cover. The influence of basement faults on diapirs depends on: the thickness and effective viscosity of the ductile layer (e.g. rock salt); the thickness ratio between the buoyant layer and the overburden; the mechanical properties of the brittle cover in the case of clastic sediments; the rate of sedimentation; the displacement rate throw and the dip of the basement faults.     

THE GEOLOGY AND HYDROCARBON HABITAT OF THE SARIR SANDSTONE, SE SIRT BASIN, LIBYA

The Jurassic — Lower Cretaceous Sarir Sandstone Cformerly known as the Nubian Sandstone) in the SE Sirt Basin is composed of four members which can be correlated regionally using a lithostratigraphic framework. These synrift sandstones unconformably overlie a little known pre‐rift succession, and are in turn unconformably overlain by post‐rift marine shales of Late Cretaceous age. Within the Sarir Sandstone are two sandstone‐dominated members, each reflecting a rapid drop in base level, which are important oil reservoirs in the study area. Between these sandstones are thick shales of continental origin which define the architecture of the reservoir units. This four‐fold lithostratigraphic subdivision of the Sarir Sandstone contrasts with previous schemes which generally only recognised three members. The sandstones below the top‐Sarir unconformity host in excess of 20 billion barrels of oil in‐place. The dominant traps are structural (e.g. Sarir C field), stratigraphic (e.g. Messla field), hanging‐wall fault plays (e.g. UU1–65 field) and horst‐block plays (e.g. Calanscio field). Three Sarir petroleum systems are recognised in the SE Sirt Basin. The most significant relies on post‐rift (Upper Cretaceous) shales, which act as both source and seal. The Variegated Shale Member of the Sarir Sandstone may also provide source and seal; while a third, conceptual petroleum system requires generation of non‐marine oils from pre‐rift (?Triassic) source rocks in the axis of the Sarir Trough. The intrabasinal Messla High forms a relatively rigid block at the intersection of two rift trends, around which stress vectors were deflected during deposition of the syn‐rift Sarir Sandstone. Adjacent troughs accommodated thick, post‐rift shale successions which comprise excellent source rocks. Palaeogene subsidence facilitated oil generation, and the Messla High was a focus for oil migration. Wrenching on master faults with associated shale smear has facilitated fault seal and the retention of hydrocarbons. In the Calanscio area, transpressional faulting has resulted in structural inversion with oil entrapment in “pop‐up” horst blocks. Elsewhere, transtensional faulting has resulted in numerous fault‐dependent traps which, in combination with stratigraphic and truncation plays, will provide the focus for future exploration.     

松南新区与长岭凹陷断陷期盆地构造解析与对比分析及有利勘探方向预测

松南新区与长岭凹陷在早白垩世均受到近EW向弧后伸展构造背景的影响,形成断坳叠置盆地,前人对于断陷期的成因机制作了大量研究,对松辽盆地断陷层划分为东、西、中三个断陷带,文章通过对松南新区与长岭凹陷断陷期盆地构造解析及其对比分析,发现松南新区与长岭凹陷断陷期的成盆机制存在较大差异。但共同点均表现出基底断裂分段发育特点,而长岭凹陷龙凤山地区的油气成功突破揭示了分段式基底断裂带“控洼-控沉-控源-控藏”的经验。因此,以长岭凹陷成功突破的经验和启示为指导,预测松南新区断陷群的有利勘探方向可在分段基底断裂附近寻源,在最大断距处寻找沉积中心,依据“主控断裂寻源、前缘相带寻储、稳定沉积寻盖、构造复原寻聚、动态演化寻藏”的思路寻找和发现新的油气藏。