鄂尔多斯盆地上古生界泥岩在油气成藏中的作用

泥岩可以作为烃源岩提供油气来源,也可以作为盖层保存油气。此外,泥岩在形成异常超压、控制地层流体分布方面也有着特殊的作用,对油气成藏有着非常重要的意义。鄂尔多斯盆地整体处于低压状态,但受泥岩排烃、欠压实影响,局部地层超压。由于区域上的直接盖层厚度较小,超压泥岩是区域油气保存的重要保障,预示着油气勘探的有利区带。盆地地层水外来补给较少,受厚层泥岩的封堵作用,矿化度和pH值整体较高,造成本区成岩作用阶段明显晚于同期同深度的其它区域地层。后期受泥岩中粘土矿物脱水作用影响,泥岩中的水释放使地层水矿化度有所降低,也形成了本区特殊的气水倒置的成藏结构。     

用方差体技术识别小断层及裂隙发育带

为了提高煤田开采的效率,准确、快速地确定断层和裂隙发育带已迫在眉睫。而三维方差体技术突出了地层横向变化对地震道的影响,能够对三维地震地质信息进行提取,还可用于识别断层、裂隙及地层的不连续变化。这里介绍了三维方差体技术的原理及基本算法,并在山东某采区三维地震资料的解释工作中进行了实际应用。结果表明,方差体技术对断层、裂隙发育带等地质异常体具有良好的识别效果。     

地震沉积学研究现状及进展综述

地震沉积学可以定义为:以高精度三维地震资料为基础,以精细沉积学模式为指导,通过综合应用地球物理技术方法,在等时地层格架内研究沉积体系分布特征及其演化的一门学科.在地球物理技术方面,重点介绍了一种新的可以自动追踪所有的等时沉积界面、基于导向体的地层切片生成方法及频谱分解中的时频分析技术.在此基础上指出了地震沉积学的发展趋势,并提出了应用地震沉积学进行沉积、构造和储层的一体化研究,进行有利区带和储层预测的新思路.     

黄骅坳陷歧南凹陷古近系沙一层序地震沉积学研究

目前国际上掀起了地震沉积学的研究热潮,国外学者在北美、印度等含油气盆地进行了一系列的地震沉积学研究,并在油气勘探和开发方面取得了明显的效果,因此本文利用相位调整和地层切片两项关键技术,对黄骅坳陷歧南凹陷沙一层序进行了地震沉积学的研究。在对研究区内各个层序界面精细解释的基础上,利用Recon软件制作了研究区内一系列的地层切片,这些切片提供了沙一层序沉积体系连续的地震图像,刻划了辫状河三角洲沉积体系在不同时期的展布范围以及水下分支河道和间湾的分布位置,为该凹陷寻找薄层隐蔽油气藏提供了较可靠的依据。     

Sediment-supply-dominated stratal architectures in a regressively stacked succession of shoreline sand bodies,Campanian Desert Member to Lower Castlegate Sandstone interval,Book Cliffs,Utah–Colorado,USA

Strongly progradational regressive stacks of shallow marine sandstones are ubiquitous in modern and ancient coastal depositional systems. Many ancient examples form prolific hydrocarbon and freshwater reservoirs in the subsurface. One of the best areas in the world to study progradational shallow marine successions is the Campanian Book Cliffs of Utah and Colorado, where the Desert Member to Lower Castlegate Sandstone interval served as a foundational data set for early sequence stratigraphic models. A strongly progradational stack of 17 parasequences comprises the Desert–Castlegate interval. Parasequences are 6·5 to 20·7 m thick. Normally regressive coarsening-upward successions are abundant, as are flat-topped, rooted foreshore sandstones. Conformable facies contacts mark the transition between the laterally adjoining nearshore terrestrial and shallow marine deposits which are genetically, temporally and spatially linked. The width of the shoreface to inner shelf facies belts varies from 4·8 to 19·9 km per parasequence, with a mean of 12·6 km. Solitary tongue shoreline trajectories are all very low to low angle ascending regressive, varying from +0·0004° to +0·171°. Stacked shoreline system trajectories are also dominantly low angle ascending regressive, with only two descending regressive trajectories, one of which intersects the depositional slope. The predominance of ascending regressive shoreline trajectories and normal regression, rarity of high frequency sequence boundaries, regressive surfaces of marine erosion and descending regressive shoreline trajectories, and absence of third-order sequence boundaries, incised valley fill deposits and no prolonged and regionally extensive sediment bypass, all point towards increasing sediment supply as the dominant driver of the Desert–Castlegate stratal architectures, while reduced accommodation (i.e. decreasing tectonic subsidence) played a secondary role.     

Coeval deposition of transgressive and normal regressive stratal packages in a structurally controlled area of the Viking Formation,central Alberta,Canada

Variability in accommodation and sedimentation rates within a basin generates significant deviations in the along-strike stratal stacking patterns of systems tracts. This variability can lead to coeval depositional units that record the juxtaposition of transgressive (retrogradational) and regressive (progradational) stratal stacking patterns. In scenarios where transgressive and regressive units are deposited concurrently, challenges arise when attempting to correlate and place systems tracts into a sequence stratigraphic framework. In these scenarios, the maximum flooding surface records a high level of diachroneity, with the position of the surface variable throughout the stratigraphic column. In this study, Viking Formation (late Albian) deposits in the Western Canada Sedimentary Basin, central Alberta, Canada, preserve significant along-strike variability of palaeoshorelines that developed in response to autogenic processes as well as allogenic controls that were active during deposition. Specifically, structural reactivation of Precambrian basement structures during Viking deposition led to significant variability in depositional environments along the palaeoshoreline. The incremental basement reactivation of the Precambrian Snowbird Tectonic Zone influenced sedimentation patterns and the creation of anomalous zones of accommodation in localized areas of the basin. Across fault boundaries and within the anomalously thick strata, both progradational and retrogradational stacking patterns occur within broadly contemporaneous deposits, complicating the correlation of stratigraphic units. While the concomitant deposition of transgressive and regressive units has been documented in a number of modern marine analogues, the concept is rarely applied to ancient successions. By identifying along-strike variabilities in shoreline geometries and incorporating the autogenic and allogenic controls that were active during deposition, a more accurate sequence stratigraphic framework can be proposed.     

沉积地质学发展新航程——地震沉积学

地震沉积学是在地震地层学和层序地层学基础上发展起来的、沉积地质学与地球物理学相互交叉的新兴学科,在刻画薄层砂体、表征储集层和预测岩性圈闭等方面发挥了重要作用。在表述地震沉积学发展简史的基础上,介绍了地震沉积学的基本概念、基本原理和主要研究流程;在建立精细层序地层格架基础上,重点阐述了90°相移、分频处理与频谱分解、属性优选、地层切片、地球物理反演、地震岩性解释和RGB(红色、绿色、蓝色)地震属性融合等地震沉积学关键技术以及地震沉积相实例分析。认为中国地震沉积学应该围绕不同类型沉积盆地开展油气勘探阶段地震地貌学(地震沉积相模式)和复杂(多样)地震岩性学综合研究,在油气开发阶段,充分利用RGB地震属性融合等多种地球物理方法技术,开展多种成因类型砂体构型和储集层定量表征研究。综合研究表明,地震沉积学是沉积地质学发展的新航程。     

准噶尔盆地春晖油田侏罗系八道湾组物源分析

春晖油田侏罗系八道湾组油层段为中砾岩、细砾岩及含砾砂岩构成的一套粗碎屑沉积,储层非均质性较强,物性与含油性密切相关。为了确定优势储层的发育方向与分布,利用重矿物法和地层倾角法对物源方向进行了研究。重矿物中ZTR指数自西北向东南方向由5增大至20以上,反映出沉积物的搬运方向为西北→东南。18口井的倾角矢量图中矢量点最多的方向也均指示为东南方向,最终确定物源为西北方向的哈拉阿拉特山,同时对近源砾石较高的磨圆度进行了分析。     

河流相砂体识别预测及古气候响应: 以渤中坳陷石南地区明下段为例

河流相砂体的识别预测及其发育演化对古气候变化的响应是当前河流相沉积研究的热点。基于地震沉积学方法,采用三步走的河流相砂体识别预测方法(井震结合建格架→90°相位调整标岩性→切片属性辨砂体),在渤海湾盆地渤中坳陷石臼坨凸起南部(石南)新近系明化镇组下段(简称“明下段”)识别出了顺直和蜿蜒河道砂、河道—堤坝复合体、点砂坝、河口坝、牛轭湖和决口扇6种河流相砂体。依据明下段泥岩颜色,结合藻类种属记录和孢粉记录分析,认为石南地区明下段沉积早期到中期经历了干湿交替→湿润主导的湿润化气候演变; 而明下段沉积中期到晚期经历了湿润主导→干旱主导的干旱化气候演变。润湿化气候演变使得明下段沉积中期河流相砂体宽度和单层厚度减小、弯曲度增大,且带状孤立河道砂体更发育; 而干旱化气候演变使得明下段沉积晚期流相砂体宽度和单层厚度增大、弯曲度减小,且带状河道—溢岸复合带和河口坝砂更发育。研究成果可为其他断陷盆地河流相砂体识别、预测提供参考,对指导构造活动相对较弱的湖盆萎缩期油气勘探实践具有一定的实践价值。     

墨西哥东南盆地白垩系裂缝综合研究——以M区块W构造为例

墨西哥东南盆地M区块W构造是区块的重点构造,W构造白垩系碳酸盐岩储层构造裂缝的发育程度决定了整个区块的勘探潜力。对周边已钻相似构造岩心和成像测井裂缝发育特征的统计表明,中白垩统地层有效裂缝最为发育,裂缝的走向主要为NW—SE向和NE—SW向。研究分析认为,裂缝的发育规律主要受到区域应力和岩性差异的控制,在此基础上建立了“盐底辟之上挤压背斜”裂缝发育模式。最终应用地层切片和曲率属性技术,预测了W构造白垩系裂缝的平面展布：裂缝集中发育在中白垩统,裂缝走向为NW—SE向,与周边钻井统计结果一致,证实了预测的可靠性。