石油开采外文翻译(宝典).doc

Oil including oil exploration is the next big subject for the Falkland Islands. We havepleasure in publishing this very full and detailed study of the oil prospects in theNorth Falkland Basin. Dr Ian Duncan is CEO of Desire Petroleum plc which is aleading operator in this field and his article is an authoritative account of the currentsituation. Petroleum Geology of the North Falkland Basin by Dr Ian Duncan CEO of Desire Petroleum plc Within the Falkland Islands designated area there are three major basins: NorthFalkland Basin Falkland Plateau Basin and South Falkland Basin. The subject of thisarticle is the North Falkland Basin where Desire Petroleum has been exploring forhydrocarbons since 1997. The North Falkland Basin is a failed rift which formed during the break-up ofthe ancient landmass of Gondwana. Plate tectonic reconstruction suggests that theentire Falklands area prior to the break-up was originally located to the South-east ofSouth Africa and moved to its present position during the opening of the SouthAtlantic during the Jurassic to the Cretaceous. The North Falkland Basin can befurther subdivided into a northern or main basin in which Tranches A to Fare locatedand a southern basin in the area of Tranches I and L. The southern basin is undrilledand 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 drillingcampaign will take place.Exploration History The first phase of exploration was in the early 1990s when Spectrum acquiredthe first detailed 2D seismic across the area. These data defined the outlines of theN-S trending North Falkland Basin approximately 180 kms long by 30 kms wide andformed the basis for the evaluation which led to the first round of licensing in 1996.Seven licences were awarded in 1997 to Shell Amerada Lasmo InternationalPetroleum Corporation IPC and Desire. These companies acquired more 2D seismicover their licences and in addition Shell acquired a small 3D survey. Shell Amerada Lasmo and IPC formed FOSA Falklands Offshore SharingAgreement jointly to conduct a drilling campaign in 1998. The semi-submersibledrilling 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 and14/10-1 Lasmo and IPC drilled one well each: 14/13-1 and 14/24-l.Drilling ended inNovember 1998. Of the six wells five recorded good oil and or gas shows but the presence ofhydrocarbons in commercial quantities was not established. Over the next few yearsAmerada Shell and Lasmo withdrew from the Falklands and as a result DesirePetroleum became the operator of Tranches C and D and Argos Evergreen became theoperator of Tranche A. Following the acquisition of further seismic in 2000 IPC wereacquired by Talisman who became the operator of Tranche F. Continuing low oil prices stifled all activity in the area until 2004 when Desireacquired 800km2 of 3D seismic over Tranches C and D. In the same year RockhopperExploration was awarded new licences in the area. At the beginning of 2005 Desire raised sufficient money to fund further drillingin the North Falkland Basin and Rockhopper farmed-in to Tranches C and D. At thetime of writing December 2005 Desire is seeking a rig to commence drilling as soonas one becomes available. During 2005 Desire assumed a 100 interest in Tranche Fand Rockhopper acquired further licences in the area. The latest licence position isshown in fig.l.Geology The North Falkland Basin has a predominantly nonmarine Jurassic to LowerCretaceous fill overlying Devonian basement. These non-marine sediments areoverlain by a marine sequence of Upper Cretaceous to Recent age. In the deepest partof the Basin in Tranche D the total section is over 5 kms in thickness. The non-marine rocks were deposited in a large lake into which flowed severallarge 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 filledslowly with fine- grained claystones which at times were deposited in oxygen-freeconditions resulting in rocks with very high organic carbon content. These rocks arethe source of the oil generated in the Basin. Eventually in the Upper Cretaceous as aresult of a significant sea level rise marine conditions became established in the Basin. The North Falkland Basin contains all the ingredients necessary for the discoveryof hydrocarbons namely source rocks reservoir rocks seals and traps.Source Rocks The 1998 drilling campaign established the presence of a thick over 1000metres non-marine oil source rock believed to be one of the richest in the world.These source rocks were immature in five of the six wells drilled but attained maturityin 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 thetemperatures and pressures are sufficiently high to generate and expel oil. Thelocation of this area of mature source rocks quotthe kitchenquot is shown in fig.3. Only thebasal part of the source rock is mature with the majority of the source rock beingimmature. Richards British Geological Survey and Hillier Shell in 2000 in which theyestimated that up to 60 billion barrels of oil had been generated and expelled from thissource rock. There is also a deeper separate source rock mature for the generation ofgas as demonstrated by the good gas shows at this deeper level in well 14/5-1.Seals The abundant claystones throughout the section including the immature upperpart of the source itself provide good sealing potential.Reservoirs Desire believes that finding effective reservoir rocks is the largest risk associatedwith the discovery of hydrocarbons in commercial quantities in this area i.e.sandstones of sufficient quality to produce oil at rates high enough to be commercial.However the seismic character of prospects such as the Liz Prospect provide goodindications that good quality reservoir rocks may be present.Traps The 2D and in particular the 3D seismic data show a number of structural andstratigraphic trapping mechanisms.Play Concept The 1000 metres thick source rock is mature only at the base in the deeper partsof the Basin. The overlying immature source rock is a very effective regional sealsee fig 4 and it is believed this has prevented the upward migration of oil into theoverlying horizons. These shallower horizons were the main target in the first drillingcampaign and the failure to find commercial hydrocarbons may be the result of thedifficulty in charging these horizons. Desire now believes that the major potential of the Basin may be in the untestedflanks of the Basin at the level of the mature oil source rock as shown in fig 4. At thislevel the oil would have only a short distance to migrate from the mature oil sourcerock to the predicted reservoir rocks. In addition the best reservoir development maybe on the flanks of the Basin. The 3D seismic data acquired in 2005 was designedspecifically 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 typesfound in the Basin.Liz Prospect This is the largest prospect and is likely to be the first one drilled in the nextcampaign. It is a stratigraphic trap and based on seismic amplitude mapping hasgeometry suggestive of a fan-delta deposited by a large river flowing into the lake seefig 5. This fan-delta is detached by faulting from the up dip feeder channel and lateralsealing is provided by the rich oil source rock which is mature at the distal end of thefan. The feeder channel shows drape on the seismic data and this is possible evidencefor the presence of coarse sandstones which are likely to provide good reservoirs. Inaddition to testing the Liz fan at the well location the edge of the Beth fan will also bedrilled. The water depth is around 350 metres and the total depth of the well will becirca 3000 metres.Ninky Prospect This is an example of a structural trap. At a number of levels immediately abovethe mature oil source rock the structural contours are closed against a fault. Unlike theLiz prospect vertical migration up a fault is required to fill the traps but on the seismica 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 quality reservoirsmight be expected but again seismic amplitude geometrics suggest that thicker distalfan sandstones might be present. This prospect is located in a water depth around 400metres with a planned total depth of circa 3100 metres.Environment Desire recognises the international importance of the environment of theFalkland Islands and is committed to doing everything possible to minimise anyimpact on the environment its operations may have. All of the operations will becarried out in accordance with UK North Sea standards and only water-based drillingmuds and low toxicity chemicals will be used. To identify all the possible impacts of the three well operation Desirecommissioned RPS one of the leading environmental consultancies in Europe toundertake an environmental impact assessment EIA. RPS suggested a number ofmeasures to minimise environmental impact and concluded that the proposedoperations can be carried out without a significant impact on the environment. Fulldetails of the EIA can be found on the Desire website at www.desireplc.co.uk.Drilling Drilling in the North Falkland Basin is relatively straightforward. The firstdrilling campaign established that there were no serious drilling hazards and that a3000 metre well could be drilled injust over twenty days. In addition the water depths350-410 metres are not considered deep in todays terms and the weather conditionsare similar to the Central North Sea. As a result a heavy duty deep water drilling rig is not required and as in theprevious campaign Desire intends to use a third generation semi-submersible rig asshown in fig 6.Development In the event of a commercial oil discovery the most likely development scenariois one now widely employed throughout the world and particularly in the North Sea.It would involve completing the producing wells on the seabed and tying them back toa FPSO Floating Production Storage and Offloading facility. Oil would betransported to a refmery located anywhere in the world by shuttle tankers. Minimalonshore facilities would be required in the Islands.Economics Based 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 fieldsare likely to be commercial. For example based on a 30/barrel oil price and a 10discount factor oil fields containing 40 million barrels would be commercial. Oilprices have risen considerably during 2005 and although costs have also risen it isbelieved the overall commerciality of a discovery has been considerably enhanced.Conclusions1. A working hydrocarbon system in the north Falkland Basin has been established.2. The area has the potential to become a major hydrocarbon province but furtherdrilling can only prove this.3. Desire has identified nine prospects for drilling and preparations are well underwayfor resumption in drilling as soon as a suitable rig can be contracted.4. An Environmental Impact Assessment has determined that a three wellexploration-drilling programme will not have a significant impact on the environment.Further explanatory diagrams can be found on Desire Website atwww.desireplc.co.uk.c. Copyright retained by Desire Petroleum plc.References: Richards P. C. and Hillier B. V. 2000 Post- Drilling Analysis of theNorth Falklands Basin - Part 2:Petroleum System and Future Prospects. Journal ofPetroleum Geology Vol23 3pp273-292.Acknowledgements: I would like to thank Dr Colin Phipps for his helpful suggestionsin the presentation of this article.石油包括石油勘探是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 AmeradaLasmo International Petroleum CorporationIPC 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，另外，shell 公司获得了小部三维调查许可。 1998 年，Shell Amerada Lasmo 和