HYDROCARBON POTENTIAL IN JORDAN

The paper presents results from a range of petroleum exploration studies carried out in Jordan – some regional in approach, others focussed on the NE of the country – together with a review of existing literature and industry reports. The dominant active structural feature in Jordan is the NNW‐SSE striking Dead Sea Transform, characterised in southern Jordan by extensional splay fault arrays, pull‐apart basins and relay‐sag basins. Elsewhere in the country there are regional‐scale strike‐slip faults (ENE‐WSW, NNW‐SSE) with multiple phases of reactivation. Stratigraphic studies have identified potential reservoir intervals within the Lower Palaeozoic Salib, Umm Sahm, Disi and upper Dubaydib (Risha Sandstone Member) Formations, and also within the Triassic and Cretaceous intervals. Potential source rocks occur within the Lower Palaeozoic Burj, lower Hiswa and Dubaydib Formations and at basal and Upper Silurian levels, with limited additional potential in the Triassic and possibly Permian successions. Apatite fission track analysis (AFTA), zircon fission track analysis (ZFTA) and vitrinite reflectance (VR) studies of selected wells and outcrop samples indicate that the thermal history of eastern Jordan is dominated by the effects of two major periods of relatively deep burial, with subsequent exhumation phases beginning in the Late Palaeozoic and Late Cenozoic. An intermediate episode (Mesozoic) of deep burial and exhumation is possible. Significant variations in heat flow regimes and burial patterns occur in different parts of Jordan, probably controlled by deep structure and burial history. Over much of the north of the country, the Lower Palaeozoic succession is in the gas window and the underlying section is overmature. The main hydrocarbon generation and expulsion phase in this region was in the Late Palaeozoic and was terminated by “Hercynian” (Late Palaeozoic) uplift. Further south, the Silurian and Upper Ordovician sections are in the oil window, and deeper source intervals are mature for gas. The Triassic interval is a valid hydrocarbon play in the NW and NE of Jordan, with oil sourced from either Permian, Triassic or Cretaceous kitchens. Upper Cretaceous source rocks within the thicker Mesozoic sections in the Azraq Graben are in the oil window and have sourced the small‐scale Hamza oilfield. In addition to the known widespread Upper Cretaceous – Paleocene oil shale potential in Jordan, the Ordovician and Silurian sections have potential for shale gas in northern Jordan and for shale oil further south.     

AN ASSESSMENT OF IRISH OFFSHORE BASINS AND PETROLEUM PLAYS

The Irish offshore contains a large number of Late Palaeozoic to Cenozoic sedimentary basins, most of which are only lightly explored. These are grouped into the Irish Sea, Celtic Sea and Atlantic Margin basins. The basins developed in response to multi-phase rifting which preceded the development of the North Atlantic Ocean. The major rift phases occurred during the Permo-Triassic, Late Jurassic and Early Cretaceous. The Irish Sea basins contain a preserved succession of predominantly Permo-Triassic and Early Jurassic age, with younger strata largely absent due to Cretaceous and Tertiary inversion. The Celtic Sea basins have a thick series of Triassic to Cretaceous strata, overlain by a generally thin Tertiary succession. The Atlantic Margin basins have a variable sedimentary thickness, with the larger basins characterized by a thick Tertiary succession. Two gasfields are currently in production in the North Celtic Sea Basin, while a number of undeveloped oil and gas accumulations have been discovered in both the North Celtic Sea Basin, and the Porcupine Basin on the Atlantic margin. A wide range of reservoir and source-rock horizons have been encountered in the various basins. Most of the exploration to date has concentrated upon structural traps, but the recent resurgence of exploration interest is centred mostly upon a variety of stratigraphic traps, especially at Cretaceous and Tertiary levels, similar to successful plays further along strike in the UK and Norwegian sectors of the Atlantic Margin.     

苏丹裂谷盆地油气藏的形成与分布——兼与中国东部裂谷盆地对比分析

晚中生代大西洋开启并诱导产生中非剪切带，在走滑的张扭力作用下形成苏丹被动裂谷盆地，早白垩世、晚白垩世和古近纪的3期裂谷垂向叠置，早白垩世具有典型的被动裂谷盆地性质，晚白垩世为过渡性质，古近纪则主动裂谷盆地特征更加明显。盆地结构以半地堑为主，但边界断层一般较陡，以多米诺式断层为主，伸展量较小。裂陷早期几乎没有火山活动，因此不存在多个次级沉积旋回，只发育一套优质烃源岩。主力储集层以石英砂岩和长石石英砂岩为主，具有高孔、高渗的特征。油气储量主要分布在后裂谷期层序中或上覆的新生裂谷层序中，具有跨时代聚集油气的特点，油气藏的主要圈闭类型以反向断块和新生裂谷层序中的大型披覆背斜为主，调节带是主要的油气聚集带。苏丹裂谷盆地油气藏特征与中国东部渤海湾等盆地的油气藏形成和分布有明显的差异。图6表1参36     

AN INTRODUCTION TO THE PETROLEUM POTENTIAL OF NIGER

The Republic of Niger can be divided into two sedimentary and tectonic provinces: a Palaeozoic platform-type province in the north and west, and a series of Mesozoic grabens in the east.
Thick Palaeozoic successions are present in the NW (in the Tamesna-Talak area of the Iullemeden Basin), and the NE (in the Djado Basin). The petroleum potential of these areas is not yet proven. By analogy with the Algerian Illizi Basin and the Libyan Murzuk Basin, Silurian source rocks together with Ordovician, Devonian and Carboniferous sandstone reservoir units may occur here.
In East Niger, a complex rift system, whose sedimentary fill ranges in age from Late Jurassic to Early Tertiary, has proven petroleum potential. Reservoir rocks are mainly Cretaceous to Eocene sandstones, sourced by Cretaceous marine shales and Oligocene lacustrine shales.
This paper reviews the petroleum geology of Niger, and assesses potential exploration targets. Commercial developments can shortly be expected following the construction of an export pipeline from Chad to Cameroon, and the resumption of drilling activity in the Agadem and Djado Basins.     

中东扎格罗斯盆地构造演化与油气分布

扎格罗斯盆地是中东地区重要的含油气盆地之一,已探明储量巨大。通过区域构造演化、盆地构造划分、油气分布特征和油气成藏主控因素研究,认为扎格罗斯盆地由被动陆缘盆地演化而成现今的前陆盆地,经历了早古生代克拉通—弧后伸展阶段、晚古生代弧后伸展阶段、中生代被动陆缘盆地阶段和晚中生代—新生代前陆盆地演化阶段。扎格罗斯山前缘断裂带和高扎格罗斯断裂带将盆地自西南向东北划分为前渊带、简单褶皱带和山前冲断带等3个构造带。扎格罗斯盆地前渊带以油田为主,简单褶皱带以气田为主,山前冲断带挤压构造变形强烈,油气难以保存。下白垩统Kazhdumi组烃源岩为中—新生界储层的主要油源,志留系Gahkum组泥页岩为古生界储层的主要气源;新生界碳酸盐岩为主力储层,其次是白垩系Sarvak组和上二叠统Dalan组碳酸盐岩;前渊带以蒸发岩和泥页岩盖层为主,简单褶皱带则以泥页岩盖层为主。背斜构造和盖层类型为油气成藏的主要控制因素。     

塔里木盆地东部断裂系统及其构造演化

通过逾3000 km地震剖面的精细解释,构建了塔里木盆地东部的断裂系统,它们分别是孔雀河断裂系统、东南断裂系统和伸展断裂系统。NW走向的孔雀河断裂系统包括古生代和早三叠世活动的孔雀河斜坡构造楔、晚侏罗世和早白垩世活动的英吉苏右行剪切挤压断裂系和新生代活动的孔雀河断裂。孔雀河断裂系统在晚古生代与塔里木地块和准噶尔地块的碰撞相关,中生代受阿莫尔海关闭构造事件的影响,新生代与印-藏碰撞相关。东南断裂系统包括志留纪的走向NE向NW逆冲的车尔臣断裂,它在白垩纪再次活动,还有新近纪和第四纪活动的NEE走向的阿尔金左行剪切挤压断裂。东南断裂系统志留纪与塔里木地块和中昆仑地体的碰撞相关,中、新生代与拉萨地体-羌塘地体碰撞和印-藏碰撞相关。伸展断裂系统发育于寒武纪、奥陶纪、早志留世、中-晚侏罗世和古近纪。     

哈萨克斯坦地区石油地质基本特征及勘探潜力分析

哈萨克斯坦位于中亚地区北部,大地构造上属于劳亚大陆南缘,即东欧克拉通和哈萨克板块南部边缘,形成晚古生代大陆边缘盆地,如滨里海盆地。古特提斯关闭使土兰地台（阿姆河-中里海）与劳亚大陆碰撞,继而形成一系列中生代裂陷盆地。哈萨克斯坦发育11个具有一定规模的沉积盆地,目前已在其中5个沉积盆地中发现商业油气,包括滨里海、曼格什拉克、北乌斯丘尔特、南图尔盖和楚河-萨雷苏盆地。哈萨克斯坦是中亚乃至世界油气最丰富的国家之一,石油和天然气可采储量分别达55×10^8t和3×10^12m^3。该国还具有很大勘探潜力,尤其是滨里海盆地,待发现可采石油资源达60×10^8t。     

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。      

全球原型盆地演化与油气分布

在全球古板块重建基础上,对全球4 091个地质单元不同地质历史时期的大地构造特征和原型盆地性质进行厘定,并以468个重点盆地为关键标定,恢复了全球前寒武纪、寒武纪、奥陶纪、志留纪、泥盆纪、石炭纪、二叠纪、三叠纪、侏罗纪、早白垩世、晚白垩世、古近纪和新近纪13个地质时期的原型盆地类型及其古、今位置分布,探讨了全球原型盆地演化规律及其与烃源岩发育和油气富集的关系。全球原型盆地的形成与板块构造演化密切相关:(1)罗迪尼亚超大陆裂解、分离阶段,主要形成克拉通盆地和被动陆缘盆地;(2)冈瓦纳大陆漂移与潘基亚超大陆的形成控制古生代被动陆缘盆地、弧后盆地和前陆盆地的共同发育;(3)潘基亚超大陆的裂解主要控制了裂谷盆地和被动陆缘盆地的发育。全球烃源岩发育与大陆裂解、海平面上升和海侵广泛有关,主要发育于拉张环境下形成的被动陆缘盆地和裂谷盆地,以侏罗纪和白垩纪最为发育。针对多期叠加型盆地,通过分别恢复不同期次的盆地原型,预测其生-储-盖组合分布与油气富集有利区,对中国石油公司开展海外战略选区和油气勘探具有重要的指导意义。     

全球原型盆地演化与油气分布

在全球古板块重建基础上,对全球4 091个地质单元不同地质历史时期的大地构造特征和原型盆地性质进行厘定,并以468个重点盆地为关键标定,恢复了全球前寒武纪、寒武纪、奥陶纪、志留纪、泥盆纪、石炭纪、二叠纪、三叠纪、侏罗纪、早白垩世、晚白垩世、古近纪和新近纪13个地质时期的原型盆地类型及其古、今位置分布,探讨了全球原型盆地演化规律及其与烃源岩发育和油气富集的关系。全球原型盆地的形成与板块构造演化密切相关：①罗迪尼亚超大陆裂解、分离阶段,主要形成克拉通盆地和被动陆缘盆地;②冈瓦纳大陆漂移与潘基亚超大陆的形成控制古生代被动陆缘盆地、弧后盆地和前陆盆地的共同发育;③潘基亚超大陆的裂解主要控制了裂谷盆地和被动陆缘盆地的发育。全球烃源岩发育与大陆裂解、海平面上升和海侵广泛有关,主要发育于拉张环境下形成的被动陆缘盆地和裂谷盆地,以侏罗纪和白垩纪最为发育。针对多期叠加型盆地,通过分别恢复不同期次的盆地原型,预测其生-储-盖组合分布与油气富集有利区,对中国石油公司开展海外战略选区和油气勘探具有重要的指导意义。     

苏北-南黄海盆地构造演化

苏北及南黄海盆地是由多期、多类盆地叠加的复合残留盆地,地质概况基本相似,成因演化近同,自元古界下扬子板块形成后,主要经历了古-中生代地台、中生代前陆盆地、走滑拉分盆地时期以及新生代断陷、坳陷盆地时期.在古生代-中生代发展过程中是一个整体,晚白垩世盆地演化出现分化,发育伸展盆地群,形成一系列叠置在中、古生代盆地之上的箕状断陷,箕状断陷的发育及分布明显受中-古生界内部先存逆冲断裂的控制.     

残留弧后盆地及其辨识准则和实例

准噶尔、塔里木和柴达木通常被认为是造山带周围的克拉通断块,因此,被称为山间盆地.作者主张这些盆地可以与黑海和里海盆地相比较,并提出准噶尔盆地形成在石碳纪,塔里木和柴达木盆地形成在二叠纪,它们是古生代亚洲南部活动边缘火山弧后面的残留盆地.这些盆地中新生代沉积物下覆层存在特大正磁异常表明,在盆地的最深处沉降有大洋岩石.在这些盆地中最老的沉积物很可能是海相页岩.在晚古生代至三叠纪期间的弧-陆碰撞后,盆地部分闭合.这些受到限制的盆地中的静海沉积物是该盆地新近发现的高产油田的很好的生油层.准噶尔、塔里木在它们与张开的海相连之后,在大陆沉积作用下成为一个内陆盆地,尔后,这些盆地被上升的山带分隔开.在构造沿晚第三纪断层重新活动以前,盆地的均衡沉降允许盆地堆积较厚的中生代和早第三纪沉积物.     

黄骅坳陷中生代构造运动对上古生界煤系烃源岩生烃演化的控制

近期,渤海湾盆地黄骅坳陷港北、乌马营和歧北等古潜山内幕与上古生界煤系有关的原生气藏勘探取得重大发现,揭示其巨大的油气资源潜力。为了深入认识该坳陷中生代构造运动对上古生界煤系烃源岩生烃演化的控制作用,采用构造解析、埋藏—热史分析、岩心薄片观察以及盆地生烃模拟等手段,综合分析了中生代构造体制与演化、盆地迁移过程、煤系烃源岩地球化学特征和生烃史,研究了中生代盆地沉降、迁移及岩浆活动对煤系烃源岩生烃的影响。研究结果表明:①黄骅坳陷中生代发生了多期、多类型的构造运动,构造事件主要有三叠纪克拉通抬升—沉降运动、侏罗纪差异压陷—压扭运动、白垩纪火山活动和伸展抬升运动;②盆地迁移过程为由南向北,孔店隆起为南、北迁移的重要界限;③黄骅坳陷上古生界煤系烃源岩经历两次生烃过程,存在着早期油气藏;④沧东凹陷上古生界煤系晚侏罗世末进入有效生烃门限,歧口凹陷上古生界煤系烃源岩早白垩世末进入生烃门限;⑤中生代构造运动对烃源岩一次生烃演化的控制主要体现在中生代各时期盆地迁移事件控制烃源岩一次生烃序列、岩浆岩局部加热事件促使烃源岩中有机质加速生烃和异常成熟等两个方面。结论认为,该研究成果明确了中生代构造运动对上古生界煤系烃源岩一次生烃演化的控制作用,对华北地区中生代构造运动、原型盆地恢复、煤系生烃演化研究以及油气勘探等都具有参考价值。     

伊盟隆起东胜地区热演化史与多种能源矿产的关系

伊盟隆起东胜地区在古生代和中生代早期,地温梯度低,烃源岩热演化程度低,中生代晚期地温梯度增高,地温梯度可达每百米3.3℃。伊盟隆起东胜地区在中生代晚期发生的构造热事件,以及后期的持续抬升是热流体运动活跃时期,并使该区石炭-二叠系、三叠系及侏罗系的煤化作用主要发生在中侏罗-早白垩世,早白垩世是古生代煤系地层的主要生气期,从早白垩世至今为煤成气的主要运移与破坏时期,也是东胜砂岩铀矿主要的成矿时期。通过镜质体反射率、磷灰石裂变径迹等资料对区内构造演化及生烃史的分析,由于伊盟隆起东胜地区石炭-二叠系及侏罗系煤系地层尚处于低成熟或未熟演化阶段,促使铀矿富集的还原剂-油气只能来自伊盟隆起以南成熟度较高地区的石炭-二叠系煤系地层。     

中国型含油气域——纪念翁文波《世界油田的分布规律》发表50周年

中国型含油气域包括中国大陆及相邻地带，被亚洲型含油气域包裹。由于陆核面积小、活动性强，经大陆增生作用，于古生代末才形成统一的地台；中、新生代又受特提斯洋消减和关闭影响而发生裂解，使得大地构造复杂程度冠于全球。含油气域内古生代、中生代和新生代的含油气层系，在一个盆地中以叠合为特点。含油气盆地除活动大陆边缘盆地外，其余内克拉通盆地已经消失，前陆盆地和裂谷盆地也都与世界典型的盆地有区别，可称为中国式的。     

On China-Type Petroleum Domains-In memory of WENG Wenbo's Distributions of Worldwide Oil Fields on the 50th anniversary of its publication

Mr.WENGWen-bohasearlyproposedtheconceptofnorth-typeandsouth-typepetroleumdomains,andcompiledCollectiveDrawingsforDistributionsofPetroleumProspectsOnshoreChina犤1犦.Theexploratoryeffortsoveronehalfcenturyhavedemonstratedhispredictions.1ResearchStatusonChin…     

On China-Type Petroleum Domains ——in memory of WENG Wenbo＇s Distributions of Worldwide Oil Fields on the 50th anniversary of its publication

China-type petroleum domains include onshore China and adjacent belts,which is enwrapped by Asia-type petroleum domain. Such small, intensively active continental nucleus did not generate a unified platform by continental overgrowth until the end of the Paleozoic, and was separated by the subducted and closed Tethys Sea during Mesozoic and Neozoic period, resulting in the most complex tectonic features in the world. Within the petroleum domains, the hydrocarbon-bearing Paleozoic, Mesozoic and Neozoic sequences were superimposed in a basin. With an exception of the active continental margin basins, the intra-cratonic basins had disappeared, and the foreland basins and rift basins were different from others in the world, so they can be called China-type basins.     

GAS-PRONE SOURCE ROCKS FROM CRATOGENE KAROO BASINS IN TANZANIA

Source-rock quality and organic matter maturity of coals and sediments from several Tanzanian Karoo basins (Permian-Triassic) have been evaluated by microscopic, pyrolytic and geochemical methods. The intracratonic Ruhuhu Basin (SW Tanzania) differs from two peripheral cratogene basins (Mikumi and Rufiji) with respect to the composition of organic matter, thermal evolution and probable hydrocarbon generation in a tensional tectonic stress field of the East African craton at the Palaeozoic/Mesozoic boundary. The Lower Permian sediments and coals and the Upper Permian sediments of the Ruhuhu Basin exhibit moderate source-rock properties. They were not subjected to significant subsidence and are moderately mature source rocks. They possibly experienced temperatures in the range 60–110d? and vitrinite reflectance values of 0.5—0.8 were attained, thus placing them within the “oil window”. Kerogen Type III is typical for all the basins, and productivity indices indicate moderate to advanced stages of evolution. The coastal basins differ in most parameters. The sediments do not have source-rock properties. High vitrinite reflectance values (1.0–2.0%) imply a higher degree of thermal maturation, and geochemical results confirm that organic matter in these sediments is postmature, and that hydrocarbon generation, if it occurred at all, ceased some time ago. The assumption of a stable geothermal gradient from Late Palaeozoic to recent times, combined with field observations, leads to the conclusion that no significant overburden has covered the Ruhuhu Basin. A mean subsidence of 1, 5OO-3,000 m, depending on basin type and stratigraphic position, seems realistic, and this overburden is provided by the sediments of the “younger Karoo cycle” (Triassic). No post-Karoo sedimentary cover was deposited in the Ruhuhu Basin. Migration probably occurred in Jurassic times, shortly after the end of the Karoo sedimentary cycle, and it is presumed that no significant tectonic activity during the Cenozoic affected pre-existing accumulations. The chances that commercial volumes of hydrocarbons (mainly gas) await discovery are fair     

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。     

THE GEOLOGY AND HYDROCARBON HABITAT OF THE BRISTOL CHANNEL BASIN

The Bristol Channel Basin forms an early Mesozoic ((?Permo-) Triassic-Jurassic) basin development with a relatively thin cover of Cretaceous and Tertiary sediments. On the basis of structural trends and stratigraphy, the Basin can be divided into two sub-basins: the ENE-WSW trending Main Bristol Channel Basin and the E-W trending East Bristol Channel Basin. In between them there is an Intermediate Area which incorporates features of the sub-basins on either side. This subdivision appears to be the result of the presence of major NW-SE basement faults which intersect the Bristol Channel area in several places. As a result of intermittent periods of tectonic activity three main stages of basin development can be recognised: (1) a (?Permo-) Triassic- Middle Jurassic stage terminated by mid-Kimmerian epeirogenetic movements, (2) an Upper Jurassic—Lower Cretaceous stage terminated by a Lower Cretaceous (late Berriasian-pre-Aptian) period of deformation, (3) an Upper Cretaceous—Tertiary stage. The bulk of the preserved sedimentary fill in the main Bristol Channel Basin consists of up to 11,000 ft of (?Permo-) Triassic-Jurassic sediments. The section is severely truncated by the overlying late Lower Cretaceoussediments or, in theirabsence, by Upper Cretaceous strata. Below the unconformity, the Upper Jurassic and, depending on their structural position, parts or the whole of the Middle and Lower Jurassic are missing. The East Bristol Channel Basin hasapreserved fill of some 7,500 ft of Triassic-Jurassic sediments. The Middle and Upper Jurassic are completely preserved in the centre of this Eastern Basin, contrasting with the situation found in the main Basin. The basin fill of both sub-basins consists largely of Triassic continental red-beds, mainly silty claystones and evaporites and Jurassic marine calcareous siltstonesand claystones. Structures are essentiully the result of the Lower Cretaceous tectonic phase(s) and are therefore mainly confined to the Triassic—Jurassic—early Lower Cretaceous sections. A number of structural traps of interest to exploration have been delineated and (unsuccessfully) tested in the Main Bristol Channel and Intermediate Area. Evaluation of the currently available data indicates that the absence of significant hydrocarbon indications in these wells is probably due to insufficient and untimely hydrocarbon generation. The possible generation is thought to have occurred prior to the main phases(s) of structural deformation, during a period of temporarily increased heatflow (Middle Jurassic—Lower Cretaceous). An additional unfavourable aspect for hydrocarbon prospects is the lack of good quality reservoir developments. From a megateetonic point of view the Bristol Channel Basin formspart of a regional rift basin development which also includes the Celtic Sea and Western Approaches Basins. The different basins and blocks of this area can, according to their behaviour during the Mesozoic, be grouped as follows: (a) the East Bristol Channel, E. of the zone of majorNWSE faults (e.g. Sticklepath fault), (b) a Central Fault Block, comprising the Cornubian Platform, the Main Bristol Channel and Haig Fras Basins, (c) Flanking Basins, such as the Intermediate Area, the Celtic Sea and Western Approaches Basins.