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1.
The analysis of Upper Jurassic and Lower Cretaceous marine sections developed in surrounding structures of the Laptev Sea revealed that all of them are composed of terrigenous rocks, which enclose abundant concretions cemented by calcareous material. The Upper Jurassic portion of the section is the most variable in thickness and stratigraphic range of sediments usually including hiatuses. Its Lower Cretaceous part represented by the Boreal Berriasian (=Ryazanian) and lower Valanginian stages is most complete. The Upper Jurassic and Lower Cretaceous sections are usually composed of fine-grained rocks (clays and mudstones) in the west and coarser cemented varieties (siltstones and sandstones) with rare mudstone intercalations in the east. Practically all the investigated Upper Jurassic and Lower Cretaceous sections include readily recognizable age and facies analogs of the Bazhenovo Formation and Achimov sandstones, which are petroliferous in West Siberia. There are grounds to assume the occurrence of these formations also on the Laptev Sea shelf, which is confirmed by seismic records. Conditions favorable for the formation of potential hydrocarbon reservoirs could exist in the western part of the paleobasin along the Nordvik Peninsula coast and northeastern Tamyr Peninsula margin. Paleotectonic reconstructions presented in this work are well consistent with stratigraphic conclusions.  相似文献   

2.
East Siberia comprises three petroleum provinces—Lena-Tunguska, Lena-Vilyuy, and Yenisey-Anabar—that occupy the area of the Siberian craton. Petroleum has been generated and has accumulated in Precambrian rifts beneath the sedimentary basins and, more importantly, within the section of the basin itself. The platformal deposits of the basins extend beneath overthrusts on the east and south and are covered by sedimentary rocks of the West Siberian overthrusts on the east and south and are covered by sedimentary rocks of the West Siberian province on the west. Permafrost and gas hydrate deposits are present throughout most of East Siberia.

In the Lena-Tunguska province, rifts that developed during Riphean time are filled by thick sedimentary rocks, in which petroleum deposits have formed. In Early Cambrian time a barrier reef extended across the East Siberian craton from southeast to northwest. A lagoon to the west of this reef was the site of thick rhythmic salt deposits, which are the main seal for petroleum in the province. The sedimentary section of the platform cover ranges in age from Late Proterozoic to Permian. More than 25 oil and gas fields have been discovered in the province, all in Riphean through Lower Cambrian rocks.

The Lena-Vilyuy province includes the Vilyuy basin and the Cis-Verkhoyansk foredeep. During Middle Devonian time, a rift formed along the axis of what was to become the Vilyuy basin. This rift is filled by Upper Devonian and Lower Carboniferous basalt, elastics, carbonates, and evaporites. During this rift stage the region that was to become the Cis-Verkhoyansk foredeep was an open geosynclinal sea. The sedimentary cover consists of Permian, coal-bearing sedimentary rocks as well as elastics from the Lower Triassic, Lower Jurassic, Lower Cretaceous, and Upper Cretaceous, the latter only in the Vilyuy basin. In the Lena-Vilyuy petroleum province as many as nine gas and gas-condensate fields have been discovered.

The Yenisey-Anabar province is largely an extension of the West Siberian petroleum province. Permian sedimentary rocks are present only in the east, where they consist of elastics and some salt. The Triassic, Jurassic, and Cretaceous each are represented by thick clastic deposits. Total thickness of the sedimentary cover is up to 15 km on the west and 8 km on the east. Twelve gas and gas-condensate fields have been discovered in the western part of the province.  相似文献   

3.
The United Arab Emirates(UAE) is the 8 th largest oil producing country and is rich in oil and gas resources. By the end of 2015, 68 oil and 23 gas fields had been discovered. The initial proved and probable(2 P) oil, gas and condensate reserves amount to 81,135.9 MMb(million barrels), 192.09 Tcf(trillion cubic feet),and 6496.58 MMb respectively, which are mostly reservoired in the Jurassic and Cretaceous carbonates. With the latest field data, this study attempts to document the salient features of petroleum systems in UAE. Based on depositional facies of source rock intervals, pods of source rocks were delineated. On the basis of an oiland gas-source correlation, five known petroleum systems were identified and they are Lower Silurian-Upper Permian Khuff gas, northeast foreland Upper Jurassic-Lower Cretaceous gas, Upper Jurassic-Jurassic petroleum, Upper Jurassic/Lower Cretaceous-Lower Cretaceous composite petroleum, and Middle Cretaceous-Middle to Upper Cretaceous/Cenozoic petroleum systems. Of them, the Upper Jurassic/Lower Cretaceous-Lower Cretaceous composite petroleum system contains 73.2% of the total 2 P reserves and thus it is the focus of this study. The Upper Jurassic and Lower Cretaceous source rocks consist of argillaceous limestone, mudstone and shale, which were deposited as intrashelf basin facies. The distribution of oil and gas in this system is controlled by the source kitchens and the regional evaporite seal.  相似文献   

4.
中亚卡拉库姆盆地油气分布特征与成藏模式   总被引:6,自引:0,他引:6  
卡拉库姆盆地是世界上仅次于西西伯利亚盆地和波斯湾盆地的第三大富气盆地。本文以获取的最新油气田储量数据为基础,采用石油地质综合分析方法,探讨了该盆地油气的层系和区域分布特征及其成藏模式。受区域盖层控制,盆地内的油气主要富集于两套层系:中侏罗统卡洛阶-上侏罗统牛津阶碳酸盐岩储集层和下白垩统欧特里阶沙特利克组砂岩储集层。前者富集了盆地内68.0%的石油储量、84.0%的凝析油储量和44.2%的天然气储量,后者富集了盆地内36.4%的天然气储量。上侏罗统蒸发岩之下的盐下油气田的区域分布主要受有利储集相带和古隆起构造展布的控制;生物礁和古构造主要发育于盆地东北部的北阿姆河亚盆地,并导致盆地内已发现的盐下油气储量主要分布于此。受蒸发岩区域盖层和深大断裂的控制,盐上油气田主要分布于蒸发岩发育区之外、蒸发岩较薄且主要为硬石膏的地区、以及蒸发岩发育区内的深大断裂附近。蒸发岩之上的盐上层系并非油气特别是天然气勘探的禁区,源自盐下烃源岩的天然气可以在盐上储集层内聚集并形成大气田。  相似文献   

5.
澳大利亚西北陆架油气资源,特别是天然气资源富集,是全球液化天然气的主要供应地之一。西北陆架不仅是澳洲油气勘探潜力最大的地区,而且也是中国油公司拓展海外油气业务的重要地区。以多方面收集的数据资料为基础,探讨澳大利亚西北陆架油气分布规律,揭示油气分布主控因素,进而优选有利勘探区。区域上,已发现的油气储量主要分布于西北陆架最西南端的北卡那封盆地;层系上,油气主要富集于下白玺统泥页岩区域盖层之下的上三叠统、侏罗系或下白玺统碎屑岩储集层。油气分布整体表现为“内油外气、下气上油、以气为主的特征,油田多局限于侏罗纪裂谷作用控制的发育有成熟生油岩的次盆地。腐殖型干酪根类型和烃源岩的高成熟度决定了西北陆架的富气特征,侏罗纪发育的裂谷控制了石油的区域分布。基于油气地质综合研究和油气发现过程,优选出了埃克斯茅斯高地、埃克斯茅斯次盆、巴科一次盆、卡斯韦尔次盆、萨胡尔台地、卡尔德尔地堑和武尔坎次盆7个有利勘探区。  相似文献   

6.
The Congo Basin in central Africa is one of the largest intracratonic sedimentary basins in the world. The geological knowledge of Congo Basin is mainly based on studies from the central part of the basin (“Cuvette Centrale”). We present the results of sedimentary provenance investigations of the Jurassic–Cretaceous strata from the southwestern part of the basin, called the Kasai region. This study combines sandstone petrography with U-Pb and Lu-Hf analyses of detrital zircons to assess the stratigraphy, sedimentary provenance and drainage history of the Upper Jurassic-Cretaceous strata in the Kasai region. The stratigraphy is subdivided into a single Upper Jurassic unit (J1) and four Cretaceous units (C1–C4). Petrographically, sandstones from all units except the conglomeratic C3 are texturally and compositionally mature, dominated by quartzarenite and subarkosic compositions. These characteristics can be attributed to considerable recycling of older sedimentary strata and crustal sources, along with long distance fluvial and aeolian processes. The analyses of fifteen detrital zircon samples from the Upper Jurassic–Cretaceous strata yielded mainly Archean and Proterozoic zircons. This result suggests that sandstones are likely sourced from the underlying Archean-Paleoproterozoic Congo–Kasai Craton and from nearby Proterozoic mobile belts, particularly the Irumide and Lufilian Belts to the south of the basin. The dominance of Archean and Proterozoic detrital zircons in Upper Jurassic–Cretaceous strata suggests that the Kasai portion of the Congo Basin experienced exhumation and erosion, which is possibly associated with far-field reactivation of Archean and Proterozoic structures during and following Gondwana rifting in the late Mesozoic. A large fluvial drainage network sourced from the south of the basin, is interpreted to have developed across central Africa during the Late Jurassic–Cretaceous. This fluvial system is believed to have flowed northward across the Congo Basin and ultimately drained into a wrench fault system called the Central African Shear Zone, which extends in an ENE direction from the Gulf of Guinea through Cameroon into Sudan and Kenya.  相似文献   

7.
The results of geodensity, geothermal, and paleotectonic modeling of some sedimentary depressions in the Far East region and central West Siberia are interpreted from a petroleum-geological standpoint. The prospects of the possibly oil-and-gas-bearing Paleogene and Upper Cretaceous rock complexes in the Lunsk, Makarovsk, and Aniva troughs, West Sakhalin uplift, and Middle Amur intermontane depression are estimated. Petroleum accumulation zones in the preplate complex are forecasted. Localization of Jurassic oil generation centers is defined at a new large oil field in the central West Siberian plate (West Siberian plate). Experience in petroleum geology modeling for structures of different tectonic patterns, lithologies, and rock ages makes it possible to recommend the adopted methodical approach and technology of gravimetric and geothermal interpretation as universal and efficient methods.  相似文献   

8.
合肥盆地中生代地层时代与源区的碎屑锆石证据   总被引:3,自引:0,他引:3  
王薇  朱光  张帅  刘程  顾承串 《地质论评》2017,63(4):955-977
合肥盆地位于大别造山带北侧、郯庐断裂带西侧,其发育过程与这两大构造带演化密切相关。本次工作对合肥盆地南部与东部出露的中生代砂岩与火山岩进行了锆石年代学研究,从而限定了各组地层的沉积时代,确定了火山岩喷发时间,指示了沉积物的源区。这些年代学数据表明,合肥盆地南部的中生代碎屑岩自下而上分别为下侏罗统防虎山组、中侏罗统圆筒山组或三尖铺组、下白垩统凤凰台组与周公山组(或黑石渡组)与上白垩统戚家桥组,其间缺失上侏罗统。盆地东部白垩系自下而上为下白垩统朱巷组与响导铺组和上白垩统张桥组。该盆地出露的毛坦厂组或白大畈组火山岩喷发时代皆为早白垩世(130~120 Ma)。盆地南部的下——中侏罗统及白垩系源区皆为大别造山带,分别对应该造山带的后造山隆升与造山后伸展隆升。而盆地东部白垩系的源区始终为东侧的张八岭隆起带,后者属于郯庐断裂带伸展活动中的上升盘。  相似文献   

9.
Paleontological study of Upper Jurassic and Lower Cretaceous sediments recovered by boreholes in the Agan-Vakh and Nadym-Vengapur interfluves clarified environments of their deposition. As is shown, influx of siliciclastic material to central areas of the West Siberian sea basin varied through time. Taxonomic composition and ecological structure of nektonic and benthic fossil assemblages are analyzed and considered in terms of environmental factors such as hydrodynamics, aeration, temperature, and salinity of seawater.  相似文献   

10.
With the aim of constraining the influence of the surrounding plates on the Late Paleozoic–Mesozoic paleogeographic and tectonic evolution of the southern North China Craton (NCC), we undertook new U–Pb and Hf isotope data for detrital zircons obtained from ten samples of upper Paleozoic to Mesozoic sediments in the Luoyang Basin and Dengfeng area. Samples of upper Paleozoic to Mesozoic strata were obtained from the Taiyuan, Xiashihezi, Shangshihezi, Shiqianfeng, Ermaying, Shangyoufangzhuang, Upper Jurassic unnamed, and Lower Cretaceous unnamed formations (from oldest to youngest). On the basis of the youngest zircon ages, combined with the age-diagnostic fossils, and volcanic interlayer, we propose that the Taiyuan Formation (youngest zircon age of 439 Ma) formed during the Late Carboniferous and Early Permian, the Xiashihezi Formation (276 Ma) during the Early Permian, the Shangshihezi (376 Ma) and Shiqianfeng (279 Ma) formations during the Middle–Late Permian, the Ermaying Group (232 Ma) and Shangyoufangzhuang Formation (230 and 210 Ma) during the Late Triassic, the Jurassic unnamed formation (154 Ma) during the Late Jurassic, and the Cretaceous unnamed formation (158 Ma) during the Early Cretaceous. These results, together with previously published data, indicate that: (1) Upper Carboniferous–Lower Permian sandstones were sourced from the Northern Qinling Orogen (NQO); (2) Lower Permian sandstones were formed mainly from material derived from the Yinshan–Yanshan Orogenic Belt (YYOB) on the northern margin of the NCC with only minor material from the NQO; (3) Middle–Upper Permian sandstones were derived primarily from the NQO, with only a small contribution from the YYOB; (4) Upper Triassic sandstones were sourced mainly from the YYOB and contain only minor amounts of material from the NQO; (5) Upper Jurassic sandstones were derived from material sourced from the NQO; and (6) Lower Cretaceous conglomerate was formed mainly from recycled earlier detritus.The provenance shift in the Upper Carboniferous–Mesozoic sediments within the study area indicates that the YYOB was strongly uplifted twice, first in relation to subduction of the Paleo-Asian Ocean Plate beneath the northern margin of the NCC during the Early Permian, and subsequently in relation to collision between the southern Mongolian Plate and the northern margin of the NCC during the Late Triassic. The three episodes of tectonic uplift of the NQO were probably related to collision between the North and South Qinling terranes, northward subduction of the Mianlue Ocean Plate, and collision between the Yangtze Craton and the southern margin of the NCC during the Late Carboniferous–Early Permian, Middle–Late Permian, and Late Jurassic, respectively. The southern margin of the central NCC was rapidly uplifted and eroded during the Early Cretaceous.  相似文献   

11.
西非海岸盆地群的形成演化受非洲板块构造演化和大西洋张裂的控制,总体上可以分为前裂谷阶段、裂谷阶段和后裂谷阶段。沿岸15个主要盆地从北往南可细分为5段,分别为北段盐盆、中段盆地、尼日尔三角洲、中南段盐盆、南段盆地。深水油气田主要发育于后裂谷阶段的上白垩统和第三系海退层序中,以油田为主。在尼日尔三角洲和中南段盐盆的下刚果盆地,所发现的油气田个数及可采储量均比较集中,个数占西非深水油气田总个数比例分别为55%和29%,占总可采储量的比例分别为48%和41%。烃源岩主要有裂谷阶段下白垩统的湖相烃源岩,后裂谷阶段上白垩统、第三系的海相烃源岩。绝大多数储层为浊积岩储层,类型以深水水道砂岩为主,其次为席状砂储层和砂质碎屑流储层。圈闭类型主要为构造-地层复合圈闭,其次为构造圈闭,另外还有地层-岩性圈闭,其所占比例较小。盐构造和泥岩塑性变形构造总体上控制了西非深水区大多数复合圈闭和构造圈闭的形成。  相似文献   

12.
1D (Petromod) hydrocarbon charge modeling and source rock characterization of the Lower Cretaceous and Upper Jurassic underlying the prolific Cretaceous and Tertiary reservoirs in the Basra oilfields in southern Iraq. The study is based on well data of the Majnoon, West Qurna, Nahr Umr, Zubair, and Rumaila oil fields. Burial histories indicate complete maturation of Upper Jurassic source rocks during the Late Cretaceous to Paleogene followed by very recent (Neogene) maturation of the Low/Mid Cretaceous succession from early to mid-oil window conditions, consistent with the regional Iraq study of Pitman et al. (Geo Arab 9(4):41–72, 2004). These two main phases of hydrocarbon generation are synchronous with the main tectonic events and trap formation associated with Late Cretaceous closure of the neo-Tethys; the onset of continent–continent collision associated with the Zagros orogeny and Neogene opening of the Gulf of Suez/Red Sea. Palynofacies of the Lower Cretaceous Sulaiy and Lower Yamama Formations and of the Upper Jurassic Najmah/Naokelekan confirm their source rock potential, supported by pyrolysis data. To what extent the Upper Jurassic source rocks contributed to charge of the overlying Cretaceous reservoirs remains uncertain because of the Upper Jurassic Gotnia evaporite seal in between. The younger Cretaceous rocks do not contain source rocks nor were they buried deep enough for significant hydrocarbon generation.  相似文献   

13.
Paleofloral and palynological records of Lower Jurassic sediments in West Siberia, Kuznetsk (Kuzbass), and Kansk-Achinsk basins and their correlation are discussed. In a number of recent papers dedicated to the Jurassic stratigraphy of Siberia this problem is ambiguously treated. The reference palynological scale has been developed for the Jurassic West Siberian sediments and an uninterrupted succession of floral assemblages associated with it and with regional stratigraphic units has been recognized. On this basis the scheme of the correlation between the Lower Jurassic sediments of the Kansk-Achinsk and Kuznetsk basins and West Siberia permitting a better age estimate of coal-bearing deposits, is proposed.  相似文献   

14.
中阿拉伯盆地是中东油气区油气资源最为富集的盆地。本文以该盆地油气田的最新资料为基础,结合盆地构造-沉积演化过程,应用石油地质综合研究方法,探讨该盆地油气的时空分布特征及主控因素。中阿拉伯盆地内发育3个主要含油气系统:下志留统含油气系统、侏罗系复合含油气系统和白垩系复合含油气系统。中阿拉伯盆地油气的层系分布表现为"下气上油",上二叠统—下三叠统储集层富集了盆地内78.9%的天然气可采储量和83.7%的凝析油可采储量,而上侏罗统—下白垩统则富集了盆地内81.9%的石油可采储量。区域上,中阿拉伯盆地的石油储量主要聚集于西海湾坳陷、迪布蒂巴赫(Dibdibah)坳陷、盖瓦尔(Ghawar)凸起和安纳拉(An N`ala)凸起,天然气和凝析油则在卡塔尔凸起更为富集。中阿拉伯盆地的油气分布主要受3个因素控制:优质区域盖层控制了油气的层系分布,主力烃源岩展布和优势运移路径控制了油气的区域分布,基底断裂和盐运动构成的圈闭控制了油气藏的形成与富集。  相似文献   

15.
塔里木盆地共发现 8套砂岩油气储层 ,对其中的 5套典型砂岩油气储层进行了自生伊利石K Ar同位素测年分析与研究。利用该项技术对其成藏史进行初步探讨是本次研究的主要目的。中央隆起下志留统沥青砂岩的自生伊利石年龄为 383.4 5~ 2 35 .17Ma ,表明志留系古油藏形成于加里东晚期—海西晚期 ;上泥盆统东河砂岩的自生伊利石年龄为 2 6 3.82~ 2 31.34Ma ,表明东河砂岩油气藏主要形成于海西晚期 ;库车坳陷依南 2气田 (依南 2井 )下侏罗统阳霞组砂岩的自生伊利石年龄为 2 8.0 8~ 2 3.85Ma ,表明油气充注发生在中新世以来 ;喀什凹陷阿克莫木气田 (阿克 1井 )下白垩统砂岩的自生伊利石年龄为 2 2 .6 0~ 18.79Ma ,表明中新世可能有古油气运移或古油藏形成 ;库车坳陷迪那 2气藏 (迪那 2 0 1井 )古近系砂岩中的伊利石主要为碎屑成因 ,不能用于进行油气成藏史研究 ,但该气藏白垩系砂岩的自生伊利石年龄为 2 5 .4 9~ 15 .4 7Ma ,表明可能为中新世成藏。本次研究表明 ,该项技术在塔里木盆地初步显示出较好的应用效果 ,具有较为广阔的应用前景。  相似文献   

16.
Weathering of pyrite in the core recovered from black shales of the Bazhenovo Formation (Upper Jurassic-Lower Cretaceous) in the West Siberian marine basin promoted the successive formation of melanterite (FeSO4 · 7H2O) and szomolnokite (FeSO4 · H2O). Szomolnokite was detected in West Siberia for the first time.  相似文献   

17.
We have studied Jurassic sections in the Predyenisei subprovince of the West Siberian petroleum basin, which were penetrated in the Vostok-1, Vostok-3, and Vostok-4 stratigraphic wells. The Urman, Togur, Ilan, Peshkovo, Tyumen’, Naunak, and Mar’yanovka Formations are described from a detailed comprehensive core analysis and log data. The depositional environment for these sediments was predominantly continental. There is evidence for short transgressions in the Ilan (Lower Toarcian) and Peshkovo (Upper Toarcian) Formations, as well as the Upper Urman (Upper Pliensbachian) and the Upper Tyumen’ (Bajocian) Subformations. In the Upper Naunak Subformation (Oxfordian), there was a change of facies from continental to littoral continental and littoral marine. The Mar’yanovka Formation developed in normal marine shallow- or moderately deep-water environments. Although good reservoirs are common throughout the Jurassic section in the southeast of West Siberia, only small, lithologically screened deposits are predicted here.  相似文献   

18.
东昆仑地区发育一套显生宙碎屑岩地层,包括下寒武统沙松乌拉组、中—上奥陶统纳赤台群、上石炭统—下二叠统浩特洛哇组、下三叠统洪水川组、中三叠统希里科特组以及上三叠统八宝山组。研究区砂岩的CIA值反映沙松乌拉组砂岩源区化学风化程度较高,其余各组砂岩源区化学风化程度较低。主量和微量元素研究结果表明各组砂岩源区以长英质岩石为主,包含少量中性成分。La、Ce、Th、U、∑REE含量和La/Sc、Th/Sc、Sc/Cr、La/Y比值指示沙松乌拉组和纳赤台群砂岩沉积环境为大陆岛弧或活动大陆边缘,浩特洛哇组砂岩形成于被动大陆边缘环境,洪水川组砂岩沉积环境为活动大陆边缘,希里科特组砂岩的微量元素含量及其比值接近于活动大陆边缘和被动大陆边缘,八宝山组砂岩沉积环境为活动大陆边缘。综合分析认为沙松乌拉组和纳赤台群砂岩形成于原特提斯洋俯冲阶段,浩特洛哇组砂岩形成于古特提斯洋持续扩张阶段,洪水川组砂岩形成于古特提斯洋俯冲阶段,希里科特组砂岩形成于陆(弧)陆初始碰撞阶段,八宝山组砂岩形成于陆陆全面碰撞—碰撞后阶段。  相似文献   

19.
东海盆地中、新生代盆架结构与构造演化   总被引:6,自引:0,他引:6  
基于地貌、钻井、岩石测年和地震等资料,分析盆地地层分布、盆架结构、构造单元划分和裂陷迁移规律,结果表明东海盆地由台北坳陷、舟山隆起、浙东坳陷、钓鱼岛隆褶带和冲绳坳陷构成,是以新生代沉积为主、中生代沉积为辅的大型中、新生代叠合含油气盆地;古元古代变质岩系构成了盆地的基底。该盆地不仅是印度-太平洋前后相继的动力体系作用下形成的西太平洋沟-弧-盆构造体系域一部分,而且也是古亚洲洋动力体系作用下形成的古亚洲洋构造域和特提斯洋动力体系作用下形成的特提斯洋构造域一部分,晚侏罗世至早白垩世经历了构造体制转换,盆地格局发生重大变革,早白垩世以前主要受古亚洲-特提斯洋构造体制影响的强烈挤压造山和地壳增厚作用演变为早白垩世以来主要受太平洋构造体制控制的陆缘伸展裂陷和岩石圈减薄作用,经历侏罗纪古亚洲-特提斯构造体制大陆边缘拗陷和白垩纪以来太平洋构造体制弧后裂陷两大演化阶段。白垩纪以来太平洋构造体制的弧后裂陷演化阶段可细分为早白垩世至始新世裂陷期、渐新世至晚中新世拗陷期和中新世末至全新世裂陷期。  相似文献   

20.
Afghanistan consists largely of a series of continental fragments that, moving northward, docked and accreted to the southern proto-Asia continent. The tectonization of the accreted terranes is generally severe and petroleum prospects are limited essentially to the 48,000 mi2 (124,000 km2) North Afghanistan basin. This basin represents the Afghan portion of the Turanian platform, plus the orogenic belt around its southern and eastern perimeter. Exploration to date is judged to be preliminary in character, with some 5 trillion cubic feet (TCF) of gas and 80 million barrels of oil being discovered by 1980. There are two types of traps: Mesozoic low-amplitude drapes or tilted fault blocks, and Neogene highamplitude folds. Appreciable reservoirs are limited to three horizons—Upper Jurassic, Lower Cretaceous, and Paleogene—of which the Lower Cretaceous is considered to be the best. Source rock is confined largely to the Lower and Middle Jurassic shales. Upper Jurassic evaporites form a barrier between the Jurassic source shales and the Lower Cretaceous reservoirs and Neogene folds. There appear to be five principal plays, and estimated total recoverable petroleum in them is 300 million barrels of oil, 9.6 TCF of gas, and 145 million barrels of condensate.  相似文献   

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