加拿大阿萨巴斯卡Kinosis区域下白垩统McMurray组内河口湾复合点坝砂体构型解剖

河口湾可分为宽阔的外河口湾和较窄的内河口湾。内河口湾水动力条件表现为潮汐影响、河流主控的特征,主要发育点坝或者线状砂坝。加拿大阿萨巴斯卡Kinosis地区发育大量潮汐作用影响的复合点坝沉积,复合点坝内部构型研究直接影响油田的开发效果。基于该区测井及高品质三维地震(频带8~220 Hz,主频90 Hz)等资料,提出1套以解决油田开发问题为核心,基于以"轴变定界、样式定型、井点定面"为原则的内河口湾复合点坝砂体构型解剖方法,研究对象为达到地震可分辨尺度的"复合砂体"。通过岩心和地震相特征分析,刻画了不同级次构型单元内部沉积特征。利用倾角测井等资料,分析了侧积体和侧积层的规模及产状,实现了点坝内部构型解剖。结果表明,内河口湾点坝沉积发育倾斜非均质层(IHS)、生物扰动、泥砾等指示潮汐作用的沉积现象;侧积体倾斜角度为8°~12°,单一侧积体宽度为55~200 m。通过复合砂体构型解剖,明确了构型单元内部隔夹层和层内水层的分布与构型单元的组合有直接关系,提出了针对单一河道单元部署井网的策略。

Using a modern analogue to interpret depositional position in ancient fluvial-tidal channels:Example from the McMurray Formation,Canada

The fluvial-tidal transition(FTT)is a complex depositional zone,where fluvial flow is modified by tides as rivers approach a receiving marine basin.Variations in the relative importance of tidal versus fluvial processes lead to a distinctive distribution of sediments that accumulate on channel bars.The FTT generally consists of three broad zones:(1)a freshwater-tidal zone;(2)a tidally influenced freshwater to brackish-water transition:and(3)a zone of relatively sustained brackish-water conditions with stronger tides.A very common type of deposit through the fluvial-tidal transition,especially on the margins of migrating channels,is inclined heterolithic stratification(IHS).At present,a detailed account of changes in the character of IHS across the FIT of a paleo-channel system has not been reported,although a number of modern examples have been documented.To fill this gap,we quantitatively assess the sedimentology and ichnology of IHS from seven cored intervals in three geographic areas situated within the youngest paleovalley("A"Valley)in the Lower Cretaceous McMurray Formation of Alberta.Canada.We compare the data to trends defined along the FTT in the present-day Fraser River in British Columbia.Canada to interpret paleo-depositional position in the ancient fluvial-tidal channels.Analysis determined that the mean mudstone thickness is 8.2 cm in the southern study area(SA).Mean thickness increases to 11 cm in the central study area(CA),and decreases again to 4.4 cm in the northern study area(NA).The proportion of mudstone is 31%in SA,44%in CA,and 27%in NA.Thicknessweighted mean bioturbation intensity in sands varied from 0.29 in SA and CA.to 0.28 in NA.On the other hand,thickness-weighted mean bioturbation intensity(Bl)in mudstone increases from 1.46 in SA.to 1.77 in CA.and is 1.94 in NA.The ichnological diversity also increased from south to north.Sedimentological results show sinilar trends to those of the Fraser River,enabling the identification of a freshwater to brackish-water transition zone with tidal influence.The interpreted position of the transition is underpinned by the bioturbation intensity and trace-fossil diversity trends,indicating periodic brackish-water conditions throughout SA in the McMurray Formation during low river flow conditions.Together,these data suggest that a broad FTT existed in the"A"Valley,with fluvial-dominated channels to the south that experienced seasonal brackish-water inundation during base flow,and channels experiencing increasing brackish-water influence lying further north towards a turbidity maximun zone.The FIT zone appears to have extended for several hundred kilometers fron south to north.Based on the sedimentological and ichnological data,as well as estimations of lateral accretion rates,we refute the colmonly applied Mississippi River depositional analogue for McMurray Formation channels.Rather,we show that while not a perfect fit,the tidally influenced Fraser River shows much greater agreement with the depositional character recorded in McMurray Formation IHS.Future work on the McMurray system should focus on characterizing tide-dominatecl deltaic and estuarine systems,such as the Ganges-Brahmaputra,and on forward-modeling the evolution of tide-dominated and tideinfluenced river systems.

加拿大Athabasca油砂矿区KN区块白垩系McMurray组中段沉积特征

加拿大Athabasca油砂矿区KN区块白垩系McMurray组中段缺乏系统的沉积特征分析。根据研究区59口井的岩心、粒度、生物遗迹、测井及高分辨率三维地震等资料,分析其沉积特征,总结沉积模式。结果表明:研究区沉积物为泥砾、砂、砂泥互层和泥等,粒度中含过渡组分,发育各种河流和潮汐成因的沉积构造及自下而上递增的过渡相生物遗迹。McMurray组中段形成于海陆交互的河口湾体系内靠近陆地一侧,是受潮汐影响的曲流河沉积,发育河床底部滞留、点坝、废弃河道和泛滥平原等微相类型。河流是正韵律下部沉积时期的主要地质营力,形成以块状层理砂为主的下点坝,是优质储层分布的位置;在正韵律的中上部,潮汐作用显现,倾斜的非均质砂泥互层IHS形成于潮汐双向水流和曲流河侧积的共同作用。该结果为优质储层评价和开发布井提供指导。

改良McMurray截骨术治疗陈旧性股骨颈骨折

目的:探讨陈旧性股骨颈骨折病人新的内固定治疗方法。方法:2002年以来,我院采用改良McMurray截骨叉状钢板内固定方法,治疗陈旧性股骨颈骨折病人21例。结果:随访1-5年,平均2.4年,临床评定:优6例,良11例,一般3例,优良率为85%。结论:改良McMurray截骨术治疗陈旧性股骨颈骨折,改变了髋关节的负重力线,增加了骨接触面积,保护了局部的血供,方法简单,疗效可靠,医疗费用低,保留了自身的股骨头,被多数患者所接受,有广泛的临床应用价值。

加拿大Athabasca地区下白垩统McMurray组沉积特征分析

在前人研究基础上,通过钻井岩心描述和测井曲线对比,根据岩石学特征、沉积相标志、测井相标志等对加拿大Athabasca地区下白垩统McMurray组进行了沉积特征分析。McMurray组主要发育了河流相、三角洲相和滨海沉积,总体呈海平面相对上升变化。纵向上,中下部层序以河流相为主,沉积物多为来自盆地周边的近物源,以西部物源为主。短河流汇入盆地后可沿盆地长轴南北发育,成为北部区块的长物源。上部层序受西北方向海侵的影响,自北向南发育滨海-河口湾-三角洲相沉积。

河口湾沉积微相分布和演化特征——针对加拿大LM油田McMurray组的分析

从区域上看,加拿大LM油田McMurray组位于下切谷中,是发育于海侵期的一套河流—河口湾沉积。依据相分析原理,在识别出8种岩相的基础上,在该组划分出6种沉积微相类型,包括河道、受潮汐影响的河道、潮道、潮汐砂坝、河漫滩和混合坪。依据层序地层学理论,综合利用岩心和测井曲线,在识别层序界面和洪泛面的基础上,在该组划分出1个长期基准面旋回、2个中期基准面旋回和3个短期基准面旋回。将短期基准面旋回的各半旋回,自下而上依次命名为S1L、S1U、S2L、S2U和S3L。在高分辨层序地层格架内对沉积微相进行分析,结果表明:微相类型呈现连续性变化,S1L发育陆相河道,S1U发育大型的受潮汐影响的河道,S2L广泛发育大型潮道,S2U发育少量小型潮道,S3L发育非常广泛的潮汐砂坝。其中,受潮汐影响的砂坝是形成最佳储层的砂体类型,其次为陆相河道砂体。

阿尔伯达盆地北极之光项目区块油砂层沉积样式

在大量钻井地质成果及岩心数据研究的基础上,对北极之光油砂项目区块McMurray组的层序及沉积环境进行了划分及对比。结合测井数据,分析了McMurray组沉积相及岩石组合特征。北极之光项目区块中,McMurray组是最重要的油砂发育层,其包含连续的河流、三角洲平原和潮控的河口湾沉积。将McMurray组划分为3段:上部———滨岸及浅海沉积、中部———河口湾及潮间带沉积、下部———陆相河流沉积。确定并讨论了每个层序的地质属性、地质时代、层序地层格架和沉积样式。根据测井数据,将其一步划分为9个亚相,部分亚相又细分成若干微相。并对其沉积模式进行了总结,提出下段河道砂体及中段河口湾及潮汐通道沉积的砂体为McMurrary组主要的油砂储集层。该认识不仅为北极之光项目的可行性提供了依据,而且可对我国在加拿大阿尔伯达盆地的油砂勘探开发工作有重要的参考作用和指导意义。