THE HYDROCARBON PROSPECTIVITY OF LOWER OLIGOCENE DEPOSITS IN THE MARAGH TROUGH, SE SIRT BASIN, LIBYA

The main phase of rifting the Sirt Basin (Libya) had ceased by the mid-Cretaceous but Alpine-related tectonic pulses in the late Eocene resulted in northward tilting of the basin. In the Maragh Trough (SE Sirt basin), a regional unconformity consequently separates Eocene carbonates from the overlying Oligocene succession. The unconformity marks a change from Eocene carbonate sedimentation to more mixed shallow-marine deposition in the Oligocene. A regional transgression re-established fully marine conditions in the Miocene.
Deeply-buried (Triassic) source rocks in the Maragh Trough reached peak oil generation during the Oligocene. Two potential reservoir intervals have been identified: upper Eocene rudstones of the Augila Formation, and unconformably-overlying sandstones of the Lower Oligocene Arida Formation. Mid-Oligocene shales provide a regional seal.
Facies distributions and reservoir properties are related to rift-related structural highs. Despite the absence of a nearby source kitchen, Upper Eocene carbonates have been found to be oil-bearing in the Maragh Trough at wells D1- and F1–96. This indicates that hydrocarbons have migrated along graben-bounding faults from deeply-buried source rocks to platform and sub-platform areas. Traps are of combined structural and stratigraphic type.     

南苏门达腊盆地中国石油合同区块成藏组合分析

南苏门达腊盆地是典型的弧后裂谷盆地，其演化经历了4大构造期：始新世中期到渐新世早期为裂谷发育期；渐新世晚期到中新世初期为裂谷-坳陷过渡期；中新世早期到末期为坳陷期；上新世早期至今为盆地反转期。盆地形成以始新统湖相泥岩、生储盖组合特征、圈闭构造风格与油气富集特点，可将其油气成藏组合划分为深部组合、下部组合、中部组合和上部组合。深部组合以新生古储式潜山油气藏为主；下部组合以自生自储式油气藏为主；中部组合以古生新储式油气藏为主；上部组合以与晚期反转构造有关的油气藏为主。3个中国石油合同区块发现的成藏组合各不相同，每一区块还具有发现其它成藏组合的潜力。     

PETROLEUM GEOLOGY AND HYDROCARBON POTENTIAL OF THE GUBAN BASIN,NORTHERN SOMALILAND

The Guban Basin is a NW‐SE trending Mesozoic‐Tertiary rift basin located in northern Somaliland (NW Somalia) at the southern coast of the Gulf of Aden. Only seven exploration wells have been drilled in the basin, making it one of the least explored basins in the Horn of Africa – southern Arabia region. Most of these wells encountered source, reservoir and seal rocks. However, the wells were based on poorly understood subsurface geology and were located in complex structural areas. The Guban Basin is composed of a series of on‐ and offshore sub‐basins which cover areas of 100s to 1000s of sq. km and which contain more than 3000 m of sedimentary section. Seismic, gravity, well, outcrop and geochemical data are used in this study to investigate the petroleum systems in the basin. The basin contains mature source rocks with adequate levels of organic carbon together with a variety of reservoir rocks. The principal exploration play is the Mesozoic petroleum system with mature source rocks (Upper Jurassic Gahodleh and Daghani shales) and reservoirs of Upper Jurassic to Miocene age. Maturity data suggest that maximum maturity was achieved prior to Oligocene rift‐associated uplift and unroofing. Renewed charge may have commenced during post‐ Oligocene‐Miocene rifting as a result of the increased heat flows and the increased depth of burial of the Upper Jurassic source rocks in localised depocentres. The syn‐rift Oligocene‐Miocene acts as a secondary objective owing to its low maturity except possibly in localised offshore sub‐basins. Seals include various shale intervals some of which are also source rocks, and the Lower Eocene evaporites of the Taleh Anhydrite constitute an effective regional seal. Traps are provided by drag and rollover anticlines associated with tilted fault blocks. However, basaltic volcanism and trap breaching as a consequence of the Afar plume and Oligocene‐Miocene rifting of the Gulf of Aden cause considerable exploration risk in the Guban Basin.     

East Venezuela盆地油气聚集与勘探潜力

East Venezuela盆地是一个大型的不对称前陆盆地,具有丰富油气资源。古生代以来,经历了晚三叠世—侏罗纪裂谷、白垩纪—始新世被动边缘和渐新世至今前陆盆地3个演化阶段。纵向上沉积地层可划分为前白垩系、白垩系和后白垩系3套巨层序。East Venezuela盆地最主要的烃源岩是Guayuta群和Tigre组海相泥页岩和碳酸盐岩。生油岩成熟度由北往南递减。北部烃源灶油气经断层、砂体长距离阶梯式向南部斜坡边缘运移。盆地最主要圈闭类型为背斜、断块、地层和岩性圈闭。Oficina组构造、构造—地层、地层圈闭组合和Naricual组构造圈闭组合是盆地内最主要的两套成藏组合。有潜力的勘探领域包括白垩系—下中新统被动边缘沉积层序、盆地中部前渊区、南部重油带和东部海域。     

PETROLEUM GEOLOGY OF THE WESTERN PART OF THE CENTRAL IRAN BASIN

Eocene extension and magmatism in Central Iran was followed by late Eocene – early Oligocene uplift, erosion, volcanism and the deposition of the continental and evaporitic sediments of the Lower Red Formation. During the late Oligocene – early Miocene, an extensional (or transtensional) phase occurred with the deposition of the limestones and marls of the Qom Formation, followed by the evaporitic deposits or mudstones of the basal part of the Upper Red Formation. Since the late Miocene, compression has resulted in regional shortening and uplift, with the deposition of the thick, clastic-dominated upper part of the Upper Red Formation and the overlying conglomeratic unit. Between 1951 and 2016, a total of 45 exploration, appraisal and development wells were drilled across the western part of the Central Iran Basin where the Alborz, Sarajeh and Aran fields are hydrocarbon discoveries. Traps at these fields are NW-SE oriented detachment folds formed during the late Miocene – Pliocene. Porous and fractured limestones in the Qom e-member are the principal reservoir units, and are capped by evaporites or mudstones in the basal part of the Upper Red Formation. Organic-rich mudstones in the Qom e- and c-members together with shales in the Jurassic Shemshak Formation are potential source rocks. An overview of 80 years of exploration efforts in the western part of the Central Iran Basin suggests that the main reasons for the general lack of success include drilling-associated problems, poor reservoir characteristics, lack of hydrocarbon charge, and underestimating the thickness of the overburden on top of the Qom reservoir.     

北黄海盆地东部坳陷油气成藏时间研究

东部坳陷是北黄海盆地唯一发现油流的沉积坳陷,具有较好的油气勘探前景,其油气藏形成时间将决定该区油气勘探思路和油气勘探方向。通过烃源岩的油气生排烃史和油层的砂岩包裹体研究,综合分析推断了东部坳陷油气藏成藏时间。研究表明,东部坳陷中侏罗统烃源岩的主要生烃期和排烃期为渐新世,下白垩统和上侏罗统砂岩储层包裹体的油充注时间为早中新世。结合盆地构造演化史综合分析推断,北黄海盆地东部坳陷的油气藏形成时间为晚渐新世至早中新世。     

南海边缘海构造旋回对沉积充填的控制——以礼乐盆地新生代沉积为例

礼乐盆地是在南海边缘海构造旋回控制下形成的沉积盆地,受古南海消亡与新南海扩张影响,盆地自晚白垩世以来经历了晚白垩世-早渐新世漂移前、晚渐新世-中中新世漂移和晚中新世-现今漂移后共3期区域演化阶段。古新世-早渐新世,礼乐盆地以滨浅海沉积为主,主要发育三角洲-扇三角洲-水下扇-盆底扇-滨海-浅海沉积体系;晚渐新世-中中新世,沉积物源供给缺乏,以滨浅海和半深海沉积为主,盆地北部发育大型碳酸盐台地;晚中新世以来,沉积物源主要来自盆地东南侧及内部火山,发育水下扇-浅海-半深海-碳酸盐台地沉积体系,以浅海和半深海沉积为主。礼乐盆地具有相对较好的烃源岩、有利的储集相带和良好的区域盖层,油气资源勘探潜力较大。     

琼东南盆地沉积环境及物源演变特征

运用沉积地球化学、古生态学等手段对琼东南盆地渐新世-中新世沉积环境及沉积物源区特征进行了分析研究,认为渐新世崖三段为淡水滨岸环境,之后海水逐步加深,由海陆过渡环境,演变到崖一段的海湾环境。盆地东部与西部在沉积物源上存在明显差异：在盆地西部的崖城隆起地区,沉积物源区存在较多的基性岩成分,特别是自陵二段开始,基性岩成分所占比例明显增高;盆地东部的松东、宝岛和松南凹陷具有明显混合物源的特性。琼东南盆地存在3套潜在的烃源岩,即始新世湖相烃源岩、渐新世海陆过渡相烃源岩和中新世半深海-深海相烃源岩,松东、宝岛凹陷陵水-三亚期的储层物性要好于松南凹陷。     

MULTIPLE PETROLEUM SYSTEMS IN TERTIARY EXTENSIONAL BASINS, EAST CHINA: A CASE STUDY OF THE GUNAN-FULIN BASIN

The Gunan-Fulin Basin, a small, extensional basin of Tertiary age, is located within the Shenglipetroleum "province" which structurally corresponds to the Jiyan megabasin in East China. The Lower Tertiary succession in the Gunan-Fulin Basin is dominated by the Eocene-lower Oligocene Shahejie Formation, which is divided into four members. Major source rocks are present in the Es3 Member (Eocene), and the Es 1 Member (Oligocene). Both units were deposited during lacustrine transgressions in the Early Tertiary. They are composed of dark, organic-rich mudstones and oil shales of lacustrine origin, and contain good quality Type I-II kerogen. The Es 1 source rock was deposited in a saline lake occasionally invaded by the sea, while the Es3 unit was laid down in a fresh-water lake.
The maturity and characteristics of these source rocks and the related crude oils can be distinguished on the basis of their biomarker contents. Es 1 source rocks and related oils are of relatively low maturity, while those of Es3 derivation are mature to highly-mature. There are therefore two separate petroleum systems in the Gunan-Fulin Basin — Eocene and Oligocene.
These petroleum systems are isolated hydraulically, and have independent migration pathways in which fault planes and unconformity surfaces play important roles. The distribution of oil accumulations in the two systems is different as a result of faulting. Oil from the Eocene source rocks is trapped in reservoirs which are distributed stratigraphically from the basement to the Tertiary, while oil from the Oligocene source rock is confined to Oligocene and Miocene reservoir rocks.
The existence of multiple petroleum systems is an important feature of Tertiary extensional basins in East China, and results from multiple phases of block faulting and a high geothermal gradient.     

东海盆地的形成及演化

东海盆地是一个大型的新生代沉积为主的盆地,沉积岩厚度超过10000m.经历了晚白垩世-古新世断陷,始新世-渐新世断坳,中新世坳陷及上新世-第四纪铺盖等四个演化阶段.并指出各个发育阶段形成了不同圈闭类型及油气歉,并认为盆地具有很好的油气远景.     

东海陆架盆地中新生代构造演化对烃源岩分布的控制作用

东海陆架盆地为发育于克拉通基底之上的中、新生代叠合盆地,该盆地经历了晚三叠世(?)—中侏罗世克拉通边缘坳陷盆地、白垩纪弧前盆地和晚白垩世末—新生代弧后裂陷盆地等3个构造演化阶段。侏罗纪盆地和白垩纪盆地主要残留在中央隆起带;新生代盆地演化在平面上表现出裂陷由西向东迁移的特征。不同时代盆地构造类型和大地构造位置控制了盆地烃源岩发育层位及平面分布:西部坳陷带以古新统月桂峰组湖相泥岩和灵峰组、明月峰组滨海相煤系地层为主要烃源岩;中央隆起带以上三叠统—中侏罗统福州组为主要烃源岩;东部坳陷带以始新统平湖组煤系地层为主要烃源岩,渐新统和中新统煤系地层为次要烃源岩。西湖凹陷天台斜坡带为中、新生代有利烃源岩的叠合区,具有“中生中储”和“新生中储”的优势,是东海陆架盆地天然气勘探的有利地区。     

苏丹迈卢特盆地石油地质特征及成藏模式

迈卢特盆地是苏丹东南部中—新生代的一个大型陆内裂谷盆地.该盆地发育了强—弱—强3期裂谷,这决定了下白垩统发育主力生油岩、古近系发育主力成藏组合.利用地震资料推断出北部凹陷是主力生烃凹陷,凹陷的半地堑结构和平面斜列特征决定了缓坡带是主力成藏带.而且盆地地温梯度偏低使成藏期偏晚,为古近系提供了充足油源.据此建立了有别于邻区Muglad等盆地和渤海湾盆地的成藏模式,明确了盆地资源潜力和有利勘探方向,为Palogue世界级大油田的快速发现提供了依据.     

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.     

台西南盆地新生代断裂特征与盆地演化

根据断裂发育特征和盆地结构分析,新生代台西南盆地的演化可划分为3个发展阶段:晚古新世—早渐新世陆缘裂陷期,此间断裂多为半地堑和地堑的边界断裂;晚渐新世—中中新世陆缘盆地坳陷期,受南海扩张运动的影响,南部坳陷发生快速拗陷,为盆地的沉降和沉积中心,而北部坳陷则处于隆起状态;晚中新世—全新世陆缘张裂期,由于南海洋壳沿马尼拉海沟向吕宋岛弧之下俯冲,致使南部坳陷沿现今的陆坡区发生一期新的张裂活动,并使南部坳陷快速沉降为深海盆,而菲律宾板块往北西方向俯冲,致使北部坳陷东部发生近东西向挤压构造运动,此时期盆地的沉积中心转移至北部坳陷。     

PETROLEUM GEOLOGY OF THE NOGAL BASIN AND SURROUNDING AREA,NORTHERN SOMALIA: PART 1, STRATIGRAPHY AND TECTONIC EVOLUTION

In this study, 92 closely‐spaced reflection seismic profiles (～4000 line‐km) were tied to biostratigraphic and lithological data from six deep exploration wells in the poorly‐known Nogal rift basin, northern Somalia, and were integrated with outcrop and aeromagnetic data to investigate the basin stratigraphy and tectonic evolution. Aeromagnetic data show NW‐SE trending magnetic anomalies which are interpreted as plutonic bodies intruded during the Early Cretaceous, probably contemporaneously with a pre‐Cenomanian uplift phase. The aeromagnetic data also suggest a change of basement type from Inda Ad Series metasediments in the SE of the study area to igneous and high‐grade metamorphic basement in the NW. Biostratigraphic data and seismic reflection profiles define the Nogal Basin as a WNW–ESE striking half‐graben, approximately 250 km long and 40 km wide, which formed as a result of mainly Cenomanian–Maastrichtian and Oligocene–Miocene intracontinental rifting. The depocentre contains at least 7000 m of Mesozoic and Cenozoic sediments and is located in the centre of the basin (east of well Nogal‐1), to the south of the Shileh Madu Range. To the north, the basin is bounded by a major border fault along which significant variations in the thickness of sedimentary units are observed, suggesting that the fault controlled basin architecture and patterns of sedimentation. Oligocene–Miocene normal faults which resulted in north‐tilted fault blocks are widespread within the main basin; smaller‐scale sub‐basins oriented NW‐SE to WNW‐ESE are observed to the NW of the basin and probably developed contemporaneously. The Late Jurassic rift phase which has been documented elsewhere in northern Somalia is either missing in the Nogal Basin or is preserved only in localised grabens in the western and central parts of the basin. This is probably due to the pre‐Cenomanian uplift and erosion which removed almost the entire Jurassic and Lower Cretaceous successions over a wide area referred to as the Nogal‐Erigavo Arch. A more pronounced rifting episode followed this erosional event in the Cenomanian–Maastrichtian and resulted in the deposition of well‐sorted fluvio‐deltaic sandstones (Gumburo and Jesomma Formations), more than 2000 m thick. In wells in the Nogal Basin, these formations are between two and three times thicker than in wells drilled in footwall locations, and include excellent reservoir rocks sealed by transgressive mudstones and carbonates. A final rifting event in the Oligocene–Miocene was related to the opening of the Gulf of Aden. A rift sag phase which accommodated the Early Oligocene continental sediments of the Nogal Group initially developed at the centre of the basin. This was followed by a period of strong rotational faulting and tilting, which reactivated the Cenomanian–Maastrichtian structures.     

EXPLORATION POTENTIAL OF TRINIDAD AND TOBAGO

The Maturin Basin of eastern Venezuela, including Trinidad. has produced approximately 9.5 billion brls of oil, and is the site of significant new discoveries at El Furrial and El Carito. The present structural basin was formed by oblique compression during Oligocene to Miocene time, with the northem flank being a folded and thrusted terrane over-riding the South American continental margin. This deformed northern flank extends into the subsurface to the basin axis, and includes the southern half of the onshore and offshore territory of the Republic of Trinidad and Tobago. The basin was infilled from west to east by deep-marine shales, turbidites, pelagic oozes and deltaic sediments of Neogene age. Deltaic sands form the reservoirs of all the important oilfields in the basin. Oil occurrence on the northern flank of the basin is associated with thrust-related structures in Venezuela and wrench-related structures in Trinidad.
There are many excellent prospects along the flanks of wrench-related ridges with diapiric cores in the Trinidad and Tobago portion of the basin. Late Pliocene and Pleistocene deltaic sands shale-out northwards in very thick aggradational lobes, enhancing the prospectivity of the southern flanks of these ridges. The prospectivity of the fold-and-thrust belt in Trinidad and Tobago is limited by the distribution of reservoir facies in pre-Pliocene sediments. Candidates for non-deltaic reservoirs are Miocene limestones, Oligocene sheet-sands, Eocene turbidites and Cretaceous fractured argillites.     

苏北盆地热史、埋藏史研究及其对南黄海南部盆地油气勘探的启示

渐新世构造抬升和新近纪地温梯度减小使得盐城组的沉积未对苏北盆地烃源岩起到增温、增熟作用。始新世、古新世地层厚度决定了阜宁组烃源岩的成熟度,戴南组的沉积厚度或残余厚度是影响区内烃源岩成熟度的关键因素;而烃源岩的成熟度控制了凹陷的资源潜力,这是苏北盆地各凹陷油气分布贫富悬殊的主要原因。南黄海南部盆地与苏北盆地属同一构造域,二者在沉积、埋藏、后期改造、成藏期及成藏要素等方面具有一定的相似性,上述认识对该盆地油气勘探具有借鉴意义,南五凹、南四凹是资源潜力相对较好的凹陷。     

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 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.     

哥伦比亚西努-圣哈辛托盆地油气地质特征

运用盆地分析及石油地质学的理论与方法,系统分析了哥伦比亚西努-圣哈辛托盆地的沉积构造演化和油气地质特征,结果表明:西努-圣哈辛托盆地主要发育白垩系及新生界沉积盖层;主要烃源岩为上白垩统Cansona组海相页岩、古新统San Cayetano组页岩及渐新统Maralu组页岩,主要储集层为古新统San Cayetano组砂岩、渐新统Cienaga de Oro组砂岩及灰岩、渐新统Pavo组砂岩,上古新统San Cayetano组泥岩、中新统Floresanto组泥岩以及部分不整合面可作为盖层。西努-圣哈辛托盆地内,与逆冲断层相关的构造圈闭和地层圈闭、与不整合面相关的地层圈闭具有良好的勘探前景。