石油开采外文翻译北福克兰盆地石油地质

《石油开采外文翻译北福克兰盆地石油地质》由会员分享，可在线阅读，更多相关《石油开采外文翻译北福克兰盆地石油地质（16页珍藏版）》请在装配图网上搜索。

1、Oil, including oil exploration, is the next big subject for the Falkland Islands. We have pleasure in publishing this very full and detailed study of the oil prospects in the North Falkland Basin. Dr Ian Duncan is CEO of Desire Petroleum plc, which is a leading operator in this field, and his articl

2、e is an authoritative account of the current situation.Petroleum Geology of the North Falkland Basinby Dr Ian Duncan, CEO of Desire Petroleum plcWithin the Falkland Islands designated area there are three major basins: North Falkland Basin, Falkland Plateau Basin and South Falkland Basin. The subjec

3、t of this article is the North Falkland Basin, where Desire Petroleum has been exploring for hydrocarbons since 1997.The North Falkland Basin is a failed rift, which formed during the break-up of the ancient landmass of Gondwana. Plate tectonic reconstruction suggests that the entire Falklands area

4、prior to the break-up was originally located to the South-east of South Africa and moved to its present position during the opening of the South Atlantic during the Jurassic to the Cretaceous. The North Falkland Basin can be further subdivided into a northern, or main, basin in which Tranches A to F

5、are located and a southern basin in the area of Tranches I and L. The southern basin is undrilled and comprises an older suite of rocks than that found in the main basin to the north. This article concentrates on the main area in Tranches C and D where the next drilling campaign will take place.Expl

6、oration HistoryThe first phase of exploration was in the early 1990s when Spectrum acquired the first detailed 2D seismic across the area. These data defined the outlines of the N-S trending North Falkland Basin, approximately 180 kms long by 30 kms wide and formed the basis for the evaluation which

7、 led to the first round of licensing in 1996. Seven licences were awarded in 1997 to Shell, Amerada, Lasmo, International Petroleum Corporation (IPC) and Desire. These companies acquired more 2D seismic over their licences and in addition Shell acquired a small 3D survey. Shell, Amerada, Lasmo and I

8、PC formed FOSA (Falklands Offshore Sharing Agreement) jointly to conduct a drilling campaign in 1998. The semi-submersible drilling rig the Borgny Dolphin was contracted and drilling began in April 1998. Amerada drilled two wells: 14/9-1 and 14/9-2; Shell drilled two wells: 14/5-1 and 14/10-1; Lasmo

9、 and IPC drilled one well each: 14/13-1 and 14/24-l.Drilling ended in November 1998.Of the six wells, five recorded good oil and or gas shows but the presence of hydrocarbons in commercial quantities was not established. Over the next few years Amerada, Shell and Lasmo withdrew from the Falklands an

10、d as a result Desire Petroleum became the operator of Tranches C and D and Argos Evergreen became the operator of Tranche A. Following the acquisition of further seismic in 2000, IPC were acquired by Talisman who became the operator of Tranche F.Continuing low oil prices stifled all activity in the

11、area until 2004 when Desire acquired 800km2 of 3D seismic over Tranches C and D. In the same year Rockhopper Exploration was awarded new licences in the area.At the beginning of 2005, Desire raised sufficient money to fund further drilling in the North Falkland Basin and Rockhopper farmed-in to Tran

12、ches C and D. At the time of writing (December 2005) Desire is seeking a rig to commence drilling as soon as one becomes available. During 2005 Desire assumed a 100% interest in Tranche F and Rockhopper acquired further licences in the area. The latest licence position is shown in fig.l.GeologyThe N

13、orth Falkland Basin has a predominantly nonmarine Jurassic to Lower Cretaceous fill overlying Devonian basement. These non-marine sediments are overlain by a marine sequence of Upper Cretaceous to Recent age. In the deepest part of the Basin in Tranche D the total section is over 5 kms in thickness.

14、The non-marine rocks were deposited in a large lake, into which flowed several large rivers which formed sandstone deltas and fans as shown schematically in fig 2. This lake was of a size similar to the present day lakes of East Africa. The lake filled slowly with fine- grained claystones, which at

15、times were deposited in oxygen-free conditions resulting in rocks with very high organic carbon content. These rocks are the source of the oil generated in the Basin. Eventually in the Upper Cretaceous as a result of a significant sea level rise marine conditions became established in the Basin.The

16、North Falkland Basin contains all the ingredients necessary for the discovery of hydrocarbons, namely source rocks, reservoir rocks, seals and traps.Source RocksThe 1998 drilling campaign established the presence of a thick (over 1,000 metres) non-marine, oil source rock, believed to be one of the r

17、ichest in the world. These source rocks were immature in five of the six wells drilled but attained maturity in one of them; live oil of 27 degree API was recorded at the surface from well 14/ 10-1.The source rocks are mature in the deeper parts of the Basin where the temperatures and pressures are

18、sufficiently high to generate and expel oil. The location of this area of mature source rocks the kitchen is shown in fig.3. Only the basal part of the source rock is mature with the majority of the source rock being immature.Richards (British Geological Survey) and Hillier (Shell) in 2000 in which

19、they estimated that up to 60 billion barrels of oil had been generated and expelled from this source rock. There is also a deeper separate source rock, mature for the generation of gas, as demonstrated by the good gas shows at this deeper level in well 14/5-1.SealsThe abundant claystones throughout

20、the section including the immature upper part of the source itself provide good sealing potential.ReservoirsDesire believes that finding effective reservoir rocks is the largest risk associated with the discovery of hydrocarbons in commercial quantities in this area; i.e. sandstones of sufficient qu

21、ality to produce oil at rates high enough to be commercial. However the seismic character of prospects such as the Liz Prospect provide good indications that good quality reservoir rocks may be present.TrapsThe 2D and, in particular, the 3D seismic data show a number of structural and stratigraphic

22、trapping mechanisms.Play ConceptThe 1,000 metres thick source rock is mature only at the base in the deeper parts of the Basin. The overlying, immature, source rock is a very effective regional seal, see fig 4, and it is believed this has prevented the upward migration of oil into the overlying hori

23、zons. These shallower horizons were the main target in the first drilling campaign and the failure to find commercial hydrocarbons may be the result of the difficulty in charging these horizons.Desire now believes that the major potential of the Basin may be in the untested flanks of the Basin at th

24、e level of the mature oil source rock as shown in fig 4. At this level the oil would have only a short distance to migrate from the mature oil source rock to the predicted reservoir rocks. In addition the best reservoir development may be on the flanks of the Basin. The 3D seismic data acquired in 2

25、005 was designed specifically to test this new model.ProspectsNine prospects have been identified (see fig.1), most of which have multiple targets. Only two of these will be described in detail to illustrate the variety of prospect types found in the Basin.Liz ProspectThis is the largest prospect an

26、d is likely to be the first one drilled in the next campaign. It is a stratigraphic trap and based on seismic amplitude mapping has geometry suggestive of a fan-delta deposited by a large river flowing into the lake see fig 5. This fan-delta is detached by faulting from the up dip feeder channel and

27、 lateral sealing is provided by the rich oil source rock, which is mature at the distal end of the fan. The feeder channel shows drape on the seismic data and this is possible evidence for the presence of coarse sandstones, which are likely to provide good reservoirs. In addition to testing the Liz

28、fan at the well location the edge of the Beth fan will also be drilled. The water depth is around 350 metres and the total depth of the well will be circa 3,000 metres.Ninky ProspectThis is an example of a structural trap. At a number of levels immediately above the mature oil source rock the struct

29、ural contours are closed against a fault. Unlike the Liz prospect vertical migration up a fault is required to fill the traps but on the seismic a fault is clearly defined reaching from the mature source rock to the overlying traps.As this prospect is near the centre of the Basin, thinner poorer qua

30、lity reservoirs might be expected but again seismic amplitude geometrics suggest that thicker distal fan sandstones might be present. This prospect is located in a water depth around 400 metres with a planned total depth of circa 3,100 metres.EnvironmentDesire recognises the international importance

31、 of the environment of the Falkland Islands and is committed to doing everything possible to minimise any impact on the environment its operations may have. All of the operations will be carried out in accordance with UK North Sea standards and only water-based drilling muds and low toxicity chemica

32、ls will be used.To identify all the possible impacts of the three well operation, Desire commissioned RPS, one of the leading environmental consultancies in Europe, to undertake an environmental impact assessment (EIA). RPS suggested a number of measures to minimise environmental impact and conclude

33、d that the proposed operations can be carried out without a significant impact on the environment. Full details of the EIA can be found on the Desire website at www.desireplc.co.uk.DrillingDrilling in the North Falkland Basin is relatively straightforward. The first drilling campaign established tha

34、t there were no serious drilling hazards and that a 3,000 metre well could be drilled injust over twenty days. In addition the water depths (350-410 metres) are not considered deep in todays terms and the weather conditions are similar to the Central North Sea.As a result a heavy duty deep water dri

35、lling rig is not required and, as in the previous campaign, Desire intends to use a third generation semi-submersible rig as shown in fig 6.DevelopmentIn the event of a commercial oil discovery the most likely development scenario is one now widely employed throughout the world and particularly in t

36、he North Sea. It would involve completing the producing wells on the seabed and tying them back to a FPSO (Floating Production, Storage and Offloading) facility. Oil would be transported to a refmery located anywhere in the world by shuttle tankers. Minimal onshore facilities would be required in th

37、e Islands.EconomicsBased on the above assumptions, a number of economic models have been run. As a result of the favourable fiscal regime in the Falklands, relatively small oil fields are likely to be commercial. For example, based on a $30/barrel oil price and a 10% discount factor, oil fields cont

38、aining 40 million barrels would be commercial. Oil prices have risen considerably during 2005 and, although costs have also risen, it is believed the overall commerciality of a discovery has been considerably enhanced.Conclusions1. A working hydrocarbon system in the north Falkland Basin has been es

39、tablished.2. The area has the potential to become a major hydrocarbon province, but further drilling can only prove this.3. Desire has identified nine prospects for drilling and preparations are well underway for resumption in drilling as soon as a suitable rig can be contracted.4. An Environmental

40、Impact Assessment has determined that a three well exploration-drilling programme will not have a significant impact on the environment.Further explanatory diagrams can be found on Desire Website at www.desireplc.co.uk.c. Copyright retained by Desire Petroleum plc.References: Richards, P. C. and Hil

41、lier, B. V., 2000 Post- Drilling Analysis of the North Falklands Basin - Part 2:Petroleum System and Future Prospects. Journal of Petroleum Geology, Vol23 (3),pp273-292.Acknowledgements: I would like to thank Dr Colin Phipps for his helpful suggestions in the presentation of this article.石油,包括石油勘探,是

42、福克兰群岛下一个大的主题。我们很高兴地出版这非常充实详细的北方福兰克群岛石油前景研究。伊恩邓肯博士是Desire Petroleum plc的首席执行官，这个领域的领头者，在现状下，他的文章是权威的。北福克兰盆地石油地质伊恩邓肯博士，Desire Petroleum plc的首席执行官在福兰克群岛指定区域有三个主要盆地：北福克兰盆地，福克兰高原盆地，南福克兰盆地。这篇文章以北福克兰盆地为主，自1997年开始Desire Petroleum已在此勘探烃类物质。北福克兰盆地是冈瓦纳古陆解体时形成的衰退峡谷。板块构造重组学说指出整个福兰克地区在解体之前侏罗纪与白垩纪南大西洋板块开放之时，从南非东南部

43、移动到现在位置。北福克兰盆地可进一步细分为南北两部分，北部也就是主要的包括A区到F区，南部盆地为I区和L区。南部盆地未被钻探，并含有一套比北部盆地老的岩层。这篇文章把重点放在将要开始钻探的C区和D区。勘探历史第一阶段的探索是在90年代初由频谱获得整个地区第一个详细的二维地震数据。这些数据指出了福兰克北部盆地轮廓,大约有180公里宽长和30公里宽,形成了1996年第一轮评价的基础。在1997年7个许可证被授予Shell, Amerada, Lasmo, International Petroleum Corporation(IPC) 和Desire公司。这些公司获得了超过许可证更多的二维地震数据

44、，另外，shell公司获得了小部三维调查许可。1998年，Shell, Amerada, Lasmo 和 IPC组成了FOSA组织（福克兰群岛海岸共享协议）来共同管理钻井工程。在1998年4月，Borgny Dolphin半潜式钻探签约并开始钻探。Amerada公司钻了两口井：14/9-1 和14/9-2井；Shell公司钻了两口井：14/5-1 和 14/10-1井; Lasmo公司和IPC公司各钻了一口井：14/13-1 和14/24-1井。钻探于1998年11月结束。在这6口井中，5口有良好的油气显示，但是烃类物质的商业储量并不足够。在以后的几年里，Amerada, Shell 和Las

45、mo公司将从福克兰地区退出，这导致Desire Petroleum公司成为C区和D区经营者，Argos Evergreen公司成为A区经营者。通过2000年更深的地震测井，Talisman获得了IPC成为F区的经营者。持续低迷的油价抑制了该地区的所有活动直到2004年获得了C区和D区800km2的地震数据。在这一年，洛克霍普勘探公司获得了这一地区的开发许可。2005年初，Desire公司斥巨资投资北福克兰盆地深部钻井，Rockhopper加入到C区和D区。在本文攥写时（2005年12月）Desire公司正在寻找钻机尽快开钻。在2005年Desire公司承担了F区100%的产权，Rockhopp

46、er获得了该地区更多的开发许可。最近的开发许可位置如图1所示。图1.北福克兰盆地目前许可和前景图地质北福克兰盆地拥有一套以陆相侏罗纪到下白垩纪为主下附泥盆纪的地层。这些陆相沉积物上附晚白垩纪到新近纪海相沉积序列。在盆地D区最深部分总截面厚度要超过5千米。这些陆相岩层在一个大的湖泊中沉积，几条大型河流汇入形成砂岩三角洲和扇形沉积，如图2所示。这个湖和现在东非的湖泊大小相近，湖中慢慢沉积细粒粘土矿物，这些物质在缺氧环境下沉积导致岩石有机碳含量很高，这些岩石是石油主要来源。最终在早白垩纪，海平面上升造成盆地海相条件确立。北福克兰群岛盆地含有寻找烃类物质的所有条件，即烃源岩，储集层，盖层和圈闭。图2.

47、北福克兰盆地下白垩纪地质图烃源岩1998年钻井确定了厚的（超过1000米）被认为是世界上最富集的陆相石油烃源岩，6口井中5口烃源岩是不成熟的，只有一口是成熟的。从井14/10-1中开采出来的石油API值为27已标记在表面。烃源岩在盆地更深部分已经成熟，那里的温度和压力已经足够高到产生和排泄石油。这一地区的成熟烃源岩“厨房”位置如图3所示。只有基部烃源岩是有大部成熟源岩组成。2000年Richards（英国地质调查）和Hiller(Shell公司)估计在这些源岩中曾产生和排泄石油600亿桶。还有一个更深的独立成熟源岩可生成天然气，就像在井14/5-1中深部良好的天然气显示一样。盖层整个地区丰富的

48、粘土矿物含有未成熟的顶部，这提供了良好的潜在封闭条件。储层Desire公司认为有效储集层的发现是该地区发现烃类物质商业储量的关键。例如，优质砂岩可产生较高的产油率可以成为商用。然而预期的地震特性如利兹预测提供的良好预测表明良好的优质储积岩会显现出来。图3.北福克兰盆地烃源岩分布图圈闭二维，特别是三维地震数据显示了大量的结构和地层圈闭机制。Play Concept1000米厚的烃源岩只有在深部盆地的基底是成熟的。上附未成熟源岩是一种有效的局部圈闭，见图4，这被认为阻挡了石油向上附岩层的运移。这些较浅地层是第一次钻井工程的主要目标，把握这些地层的困难可能是导致商业烃化物发现失败的原因。图4. 未检

49、测区域Desire公司认为主潜力盆地可能位于与图4所示烃源岩同一水平位置的未检测盆地的两翼部分。从这一位置，石油从成熟烃源岩到预测储积岩只有很短一段距离。此外，最好的油气开发可能位于盆地的两翼。2005年三维地震数据的获得就是专门为测试这个新模型而设计的。前景预测9个前景已经被认同（图1），多种拥有多重目标。只有他们中的两个将被详细的描述以说明这个盆地所发现前景类型的多样性。利兹预测这将是最大的也是下一轮钻井工程第一个勘探预测。这是一个地层圈闭，基于地震振幅映射显示有一个入湖大型河流沉积形成的扇形三角洲（图5所示）。这个扇形三角洲从上部倾斜断层分离，侧圈闭由富含石油的源岩组成，它们在三角洲的末

50、端是成熟的。补给通道显示了地震数据上的褶皱，这可能是形成良好储层的粗砂岩存在的证据。除了位于井口位置的三角洲需要利兹检测外，位于贝丝三角洲的边缘部分也需要钻探。水深大概有350米，井的总深大概有3000米。Ninky预测这是一个典型的构造圈闭。在成熟烃源岩上部的大量水平位置，构造轮廓在断层处是闭合的。不像利兹预测那样油气沿断层垂向运移充满整个圈闭，而是基于地震，断层从成熟烃源岩到上覆圈闭明确定义。图5.上白垩纪沉积环境利兹预测前景图由于这次勘探是在盆地中心进行，细薄储层可能被发现，但是地层振幅映射显示，厚的远端三角洲砂岩可能会出现。这次钻探位于水深约400米总计划深度约3100米深的地方。环境

51、Desire公司承认福克兰群岛环境的全球重要性并承诺会做任何可能的事情把开发带来的环境危害最小化。所有的开发均按照英国北海标准进行，只有水基钻井和低毒化学物质会被使用。为了确定三口井开发可能带来的影响，Desire公司委托RPS公司，欧洲环境评估的领导者，来进行环境影响评估（EIA）。RPS提出了大量的把环境影响最小化的措施并得出结论：被提议的业务可以操作并不给环境带来大的影响。环评详情可见Desire公司网站 www.desireplc.co.uk 。钻井北福克兰盆地钻探是相当简单的。第一轮钻井工程确定没有太大的钻井危害，一个3000米深的井可以20天内完成。另外，水深（350-410米）在

52、今天看来也不深，天气状况和中央北海类似。结果不再需要深水重型钻机，在以往工程中，Desire公司需要使用第三代半潜式钻机，如图6所示。图6.半潜式钻井设备图发展在商业石油勘探史上，最可能的开发方案是世界上广泛应用特别是在北海的开发方案。它包括海底产油井的完成和变成浮动的生产、储存和卸载设施。石油将被来回穿梭的油轮运输到任何地方的炼油厂。岛上可能会需要最小的设施。经济基于以上的假设，大量的数经济学模型已经建立。由于福克兰群岛优惠的财政政策，相对较小的油田可能成为商用。例如，基于30美元/桶的石油价格和10%的折现因子，含有40,000，000桶的油田就有商用价值。尽管开发成本有所增长，但是200

53、5年石油价格也有大幅攀升，商业勘探从整体上看是平衡的。结论1. 北福克兰盆地油气生成系统已经确立。2. 这一地区有潜力成为主要的油气省，但只有进一步的钻井才能证明这一点。3. Desire公司已经确立了9个勘探前景，钻井恢复准备工作正在逐步进行，只要合适的钻机已签订。4. 环境评估最终显示钻井开发工程不会对环境带来显著的影响。更多的开发项目可以在Desire公司网站上获得www.desireplc.co.uk。参考文献：Richards, P. C. and Hillier, B. V., 2000 Post-Drilling Analysis of the North Falklands Basin - Part 2:Petroleum System and Future Prospects. Journal of Petroleum Geology, Vol23(3),pp273-292. 声明：我非常感谢罗林佩利普斯博士在本文的写作过程中所提供的建议。