准中1区三工河组二段低孔渗储层特征及主控因素

通过岩芯观察、测井和录井资料、铸体薄片观察,研究准中1区三工河组二段储层特征及致密化因素。研究表明,储层砂体发育于水下分流河道、河口砂坝和远沙坝;储集岩以长石岩屑砂岩、岩屑砂岩为主;储集空间以次生溶孔为主,含少量原生孔隙,为孔缝型储层。储层受原生沉积相和后生成岩作用改造的双重控制。强烈的压实作用、钙质胶结是导致储层致密的主要因素,后期深埋溶蚀则是储层得以改造的关键控制因素。优质储层主要发育于水下分流河道,表现为粗粒、弱压实、弱钙质胶结、强溶蚀微观特征。     

断陷湖盆缓坡带古河道定量恢复方法及油气地质意义：以霸县凹陷文安斜坡东营组为例

河流沉积砂体定量表征是油田高效勘探开发的重要基础。文章综合利用定量岩心分析、测井相分析、定量地震沉积学和三维地震剖面识别方法,对霸县凹陷文安斜坡东营组古河道砂体厚度,河道（带）宽度,（满岸）河道水深等河流参数进行了定量化计算。研究表明,文安斜坡东营组发育北部苏桥、中部文安和南部长丰镇三个物源输入口,河流呈NEE-SWW向分散于文安斜坡带,其中河道带宽度（w）为1.04~2.61 km,平均宽度（wcb）为1.71 km;主河道宽度（W）为15.2~179.6 m,平均宽度（Wc）为84.4 m;主河道沉积水深（D）为1.34~5.21 m,平均水深（Dc）为3.29 m;主河道满岸水深（Dmax）为2.35~9.15 m,平均满岸水深（Dmaxa）为5.77 m;主河道沉积厚度（H）为2.15~8.32 m,平均厚度（Hc）为5.25 m,河道长度（L）为18.5~28.2 km,平均河道带长度（Lcb）为25.1 km,流向（A）为40°~65°。确定文安斜坡东营组发育辫状河沉积,斜坡东侧中外带为主要的砂岩卸载区,河流以垂向挖掘性河流为主,侧向迁移为辅,河道砂岩平面呈“条—带”状。文安斜坡西侧内带以侧向迁移河流为主,下蚀作用为辅,河道砂岩呈“席—带”状。东营组河道砂岩具有“下生上储”的有利成藏条件,具有良好的岩性、构造—岩性圈闭（油气藏）勘探前景。     

CCSD主孔榴辉岩中磷灰石的矿物化学特征及对榴辉岩中F、Cl、Sr等元素地球化学行为的影响

为探讨榴辉岩中磷灰石的矿物化学特征及榴辉岩中某些相关元素的地球化学行为,对中国大陆科学钻探(CCSD)主孔500~540m深度的榴辉岩样品进行了岩石化学及磷灰石的矿物化学分析。这些榴辉岩具有不同的矿物组成和化学成分,并可据此分为上下两段,上段500~530m为正常榴辉岩,下段530~540m为高Ti榴辉岩和高Ti-Fe榴辉岩,其原岩可能为类似于辉长质和苦橄质的基性—超基性岩石。其中的磷灰石成分没有明显差别,均为氟—磷灰石,其富F贫Cl的特征可能是造成榴辉岩中高盐度流体包裹体和全岩高F低Cl的主要原因。磷灰石普遍含有一定的Sr、S、Fe元素,多数还含有Cu、Pb、Zn等元素。榴辉岩中P2O5含量与其F、Cl、Sr、S元素的相关程度表明,磷灰石是榴辉岩中F元素的最主要储存库,也是Sr元素的重要储存库之一,而对于Cl元素则只是部分控制,与S元素则没有相关性。榴辉岩中F、Sr及Cl元素的地球化学行为主要受控于磷灰石,因此,在榴辉岩从进变质—退变质过程中,这些元素的活动性直接受控于磷灰石的稳定性。     

蜀南地区下三叠统飞仙关组沉积相

蜀南地区飞仙关组的沉积相类型主要有浑水陆棚相与清水陆棚相,东部两者交替发育,中西部则主要为浑水陆棚相。浑水陆棚相以半局限海亚相为主,包括三个微相;清水陆棚相可分为颗粒滩、滩间、潮坪和内缘斜坡等四个亚相,包括若干微相。飞一段全区为清水陆棚相;飞二段全区均为浑水陆棚亚相的泥质半局限海微相;飞三段,西部为浑水陆棚相,东部为清水陆棚相,其间发育灰泥质半局限海微相;飞四段基本为泥质半局限海微相。飞一时,区内中部有一近南北向的台内凹槽,沿凹槽边缘鲕粒滩较发育。研究区以西的康滇古陆和龙门山岛链与华蓥山断裂带控制着区内沉积相展布,当康滇古陆和龙门山岛链构造活跃时全区发育浑水陆棚,华蓥山断裂带活动时东部发育清水陆棚;当康滇古陆、龙门山岛链与华蓥山断裂带构造的活动性都较低时,全区以清水陆棚为主。     

柴达木盆地第三系咸水湖相生油岩古沉积环境地球化学特征

在系统分析柴达木盆地西部第三系咸水湖相生油岩样品的微量元素、有机物、粘土矿物组成的基础上,揭示了研究区生油岩的无机元素和有机质组成特征;并结合沉积环境的无机与有机地球化学指标,重建了生油岩沉积时的古沉积环境。生油岩的B、Cl-及伽玛蜡烷含量表明,沉积时的水介质条件是半咸水—咸水环境,并伴随湖盆沉积中心北迁过程各层位地层的盐度发生规律性时空]化;生油岩的Fe2 /Fe3 、S2-、Pr/Ph比值、藿烷碳数分布模式及黄铁矿含量反映其沉积时的沉积环境为强还原性;粘土矿物组合特征及含量揭示这些生油岩的沉积相带介于中心咸湖相和边缘咸湖相之间。     

海南岛福山凹陷古近系流沙港组沉积相

古近系流沙港组沉积时期是海南岛福山凹陷的主要成盆期,沉陷幅度较大,地势较陡,由此导致流沙港组深水湖泊沉积和辫状河三角洲沉积相当发育。通过对岩心、测井和地震等资料的综合分析,分别对流沙港组3个岩性段的沉积相进行了研究。单井沉积相和平面沉积相分析表明流沙港组主要发育辫状河三角洲相和湖泊相,并可进一步划分出7种亚相和13种微相。流三段沉积时期辫状河三角洲沉积最为发育,约占研究区总面积的一半,仅在研究区北部为半深湖亚相—深湖亚相分布区。流二段沉积时期是福山凹陷最大湖侵期,深水湖泊相最为发育,研究区北半部几乎全为深湖亚相—半深湖亚相分布区。流二段沉积之后,凹陷周缘发生较大范围隆升,因此,流一段沉积时期的沉积范围比流二段沉积时期小得多,但其沉积相展布格局与流二段沉积时期仍比较相似。通过对ZTR指数(代表锆石、金红石、电气石三种重矿物在透明重矿物中所占的比例)等值线图、砂(砾)岩百分含量等值线图及沉积相展布格局等分析认为,流沙港组沉积时期的物源主要来自南方的海南隆起,东、西方向还存在2个次要物源。     

柴达木盆地北缘结绿素-红山地区古新统至中新统沉积相

根据柴达木盆地北缘露头剖面、钻井剖面的地层学和岩石学研究所取得的各种定量及定性资料,采用冯增昭教授倡导的单因素分析多因素综合作图法,编制了柴达木盆地北缘结绿素—红山地区古新统—始新统、渐新统和中新统的各种单因素图和沉积相图。这是首次将定量的沉积相研究方法应用于柴达木盆地的古新统至中新统。结绿素—红山地区古新统至中新统发育2种沉积相类型,即冲积扇和辫状河。其中辫状河可划分为砾质辫状河和砂质辫状河。古新世—始新世发育冲积扇—辫状河—湖泊沉积体系,渐新世—中新世发育辫状河—湖泊沉积体系。从古新世到中新世,柴达木盆地北缘经历了由大规模冲积扇沉积到辫状河沉积的演化过程。     

珠江口盆地阳江东凹裂陷期沉积环境及其构造控制

珠江口盆地阳江东凹形成于古近纪裂陷期,广泛发育烃源岩的富存层段——文昌组、恩平组,具有陆相断陷盆地沉积以及构造控制下多幕演化的特征.沉积环境演变以及构造?沉积的耦合作用是陆相断陷盆地的重要研究方向,认识其动态过程可为烃源岩识别和油气评价建立基础.本文从三维地震资料、钻井资料入手,通过地震反射特征和井震联合分析,划分了研...     

An iron-bearing wave-dominated siliciclastic shelf: Facies analysis and palaeogeographic implications (Silurian-Lower Devonian Sierra Grande Formation,Southern Argentina)

The Sierra Grande Formation (Silurian-Early Devonian) consists of quartz arenites associated with clast supported conglomerates, mudstones, shales and ironstones. Eight sedimentary facies are recognized: cross-stratified and massive sandstone, plane bedded sandstone, ripple laminated sandstone, interstratified sandstone and mudstone, laminated mudstone and shale, oolitic ironstone, massive conglomerate and sheet conglomerate lags. These facies are interpreted as shallow marine deposits, ranging from foreshore to inner platform environments. Facies associations, based on vertical relationships among lithofacies, suggest several depositional zones: (a) beach to upper shoreface, with abundant plane bedded and massive bioturbated sandstones; (b) upper shoreface to breaker zone, characterized by multistorey cross-stratified and massive sandstone bodies interpreted as subtidal longshore-flow induced sand bars; (c) subtidal, nearshore tidal sand bars, consisting of upward fining sandstone sequences; (d) lower shoreface zone, dominated by ripple laminated sandstone, associated with cross-stratified and horizontal laminated sandstone, formed by translatory and oscillatory flows; and (e) transitional nearshore-offshore and inner platform zones, with heterolithic and pelitic successions, and oolitic ironstone horizons. Tidal currents, fair weather waves and storm events interacted during the deposition of the Sierra Grande Formation. However, the relevant features of the siliciclastics suggest that fair weather and storm waves were the most important mechanisms in sediment accumulation. The Silurian-Lower Devonian platform was part of a continental interior sag located between southern South America and southern Africa. The Sierra Grande Formation was deposited during a second order sea level rise, in which a shallow epeiric sea flooded a deeply weathered low relief continent.     

Clinoform architecture and along‐strike facies variability through an exhumed erosional to accretionary basin margin transition

Exhumed basin margin‐scale clinothems provide important archives for understanding process interactions and reconstructing the physiography of sedimentary basins. However, studies of coeval shelf through slope to basin‐floor deposits are rarely documented, mainly due to outcrop or subsurface dataset limitations. Unit G from the Laingsburg depocentre (Karoo Basin, South Africa) is a rare example of a complete basin margin scale clinothem (>60 km long, 200 m‐high), with >10 km of depositional strike control, which allows a quasi‐3D study of a preserved shelf‐slope‐basin floor transition over a ca. 1,200 km² area. Sand‐prone, wave‐influenced topset deposits close to the shelf‐edge rollover zone can be physically mapped down dip for ca. 10 km as they thicken and transition into heterolithic foreset/slope deposits. These deposits progressively fine and thin over tens of km farther down dip into sand‐starved bottomset/basin‐floor deposits. Only a few km along strike, the coeval foreset/slope deposits are bypass‐dominated with incisional features interpreted as minor slope conduits/gullies. The margin here is steeper, more channelized and records a stepped profile with evidence of sand‐filled intraslope topography, a preserved base‐of‐slope transition zone and sand‐rich bottomset/basin‐floor deposits. Unit G is interpreted as part of a composite depositional sequence that records a change in basin margin style from an underlying incised slope with large sand‐rich basin‐floor fans to an overlying accretion‐dominated shelf with limited sand supply to the slope and basin floor. The change in margin style is accompanied with decreased clinoform height/slope and increased shelf width. This is interpreted to reflect a transition in subsidence style from regional sag, driven by dynamic topography/inherited basement configuration, to early foreland basin flexural loading. Results of this study caution against reconstructing basin margin successions from partial datasets without accounting for temporal and spatial physiographic changes, with potential implications on predictive basin evolution models.