鄂尔多斯盆地东部二叠系山西组23段石英砂岩砂体结构类型及成岩作用差异*

鄂尔多斯盆地东部子洲—清涧地区二叠系山西组2₃段石英砂岩区块单井产能与砂体结构类型具有一定相关性。基于单砂体垂向粒度韵律和自然伽马测井资料,将砂体结构划分出块状型砂体、正粒序型砂体和叠加型砂体3种类型。通过铸体薄片鉴定和粒度分析实验,对3种类型砂体储集层在成岩作用类型、特征、发育程度、产物、垂向变化及成岩孔隙演化的差异性进行表征。研究表明,3类砂体的溶蚀作用、压实作用强度及分布特征存在较大差异,粒度及其垂向分布是制约不同结构类型砂体成岩演化的直接因素,进而影响储集层物性,决定了含气层与致密层的垂向分布规律。块状型砂体储集层原生孔隙、次生溶孔共同发育,含气层厚度较大,局部致密。正粒序型砂体垂向物性差异较大,中—下部储集层溶蚀程度较弱,以原生孔隙为主,次生孔隙少量发育,为含气层;上部储集层压实、胶结作用强烈,相对致密。叠加型砂体储集层形成于河流控制作用逐渐增强的过渡环境,兼有正粒序型、块状型砂体的特征,多层含气且厚度大。     

Internal anatomy of a mixed siliciclastic–carbonate platform: the Late Cenomanian–Mid Turonian at the southern margin of the Spanish Central System

The Late Cenomanian–Mid Turonian succession in central Spain is composed of siliciclastic and carbonate rocks deposited in a variety of coastal and marine shelf environments (alluvial plain–estuarine, lagoon, shoreface, offshore‐hemipelagic and carbonate ramp). Three depositional sequences (third order) are recognized: the Atienza, Patones and El Molar sequences. The Patones sequence contains five fourth‐order parasequence sets, while a single parasequence set is recognized in the Atienza and El Molar sequences. Systems tracts can be recognized both in the sequences and parasequence sets. The lowstand systems tracts (only recognized for Atienza and Patones sequences) are related to erosion and sequence boundary formation. Transgressive systems tracts are related to marine transgression and shoreface retreat. The highstand systems tracts are related to shoreface extension and progradation, and to carbonate production and ramp progradation. Sequences are bounded by erosion or emergence surfaces, whose locations are supported by mineralogical analyses and suggest source area reactivation probably due to a fall in relative sea‐level. Transgressive surfaces are subordinate erosion and/or omission surfaces with a landward facies shift, interpreted as parasequence set boundaries. The co‐existence of siliciclastic and carbonate sediments and environments occurred as facies mixing or as distinct facies belts along the basin. Mixed facies of coastal areas are composed of detrital quartz and clays derived from the hinterland, and dolomite probably derived from bioclastic material. Siliciclastic flux to coastal areas is highly variable, the maximum flux postdates relative sea‐level falls. Carbonate production in these areas may be constant, but the final content is a function of changing inputs in terrigenous sediments and carbonate content diminishes through a dilution effect. Carbonate ramps were detached from the coastal system and separated by a fringe of offshore, fine‐grained muds and silts as distinct facies belts. The growth of carbonate ramp deposits was related to the highstand systems tracts of the fourth‐order parasequence sets. During the growth of these ramps, some sediment starvation occurred basinwards. Progradation and retrogradation of the different belts occur simultaneously, suggesting a sea‐level control on sedimentation. In the study area, the co‐existence of carbonate and siliciclastic facies belts depended on the superimposition of different orders of relative sea‐level cycles, and occurred mainly when the second‐order, third‐order and fourth‐order cycles showed highstand conditions.     

地震沉积学在识别重力流沉积体系中的应用

探讨地震沉积学方法在识别陆相断陷盆地重力流沉积体系的研究思路。以歧口凹陷歧南斜坡沙一段的深水厚层砂岩为研究对象, 在现代沉积学和地震沉积学理论和方法的指导下、分频解释和时频分析技术建立高频等时格架的基础上, 通过岩芯相精细描述确定沙一段主要发育重力流水道沉积体系。形成了以古地貌和地震属性约束物源方向, 预测重力流水道的宏观展布;地层切片、反演与三维可视化相结合刻画砂体空间展布形态的断陷湖盆沟道型重力流地震沉积学识别方法和技术。应用该方法对歧南斜坡重力流水道砂体进行了精细刻画, 为在歧口凹陷广泛发育的湖相泥岩中寻找岩性油气藏开辟新的勘探领域, 并在歧口凹陷油气勘探中取得了良好的应用效果, 同时也丰富和发展了断陷盆地重力流沉积体系的地震沉积学研究成果。     

地震沉积学在识别陆相湖泊浊积砂体中的应用

地震沉积学是一门新兴边缘交叉学科,它以三维地震数据为基础,结合岩心、测井等资料,通过先进的地球物理技术,对沉积微相进行精细研究。胜利油田滨682井区沙三中、下亚段以近岸水下扇、浊流和半深湖-深湖沉积为主,浊积砂是该层主要的产油砂体。为了分析该地区浊积砂的分布规律,在地震沉积学理论指导下,运用90°相位调整技术和地层切片技术对滨682井区目的层段进行了研究。研究结果认为：垂向上,滨682井区沙三下亚段的下部和上部以及沙三中亚段的下部和上部是浊积砂体发育的有利层段;在平面上,沙三下亚段沉积早期浊积砂体主要发育在研究区东南部,面积最大可达1.71 km²;沙三下亚段沉积晚期浊积砂体在东部、东南部和南部都有发育,南部浊积砂体面积较大,可达3.37 km²,东南部和东部浊积砂体面积较小,在1.61 km²左右;沙三中亚段沉积早期浊积砂体发育在研究区东北和东南,面积可达1.90 km²;沙三中亚段沉积晚期浊积砂体发育在研究区西部和东南部,面积都较小,一般为1.15 km²。     

北部湾盆地涠西南凹陷南坡古近系流二段滩坝砂体分布规律

涠西南凹陷南坡H 1井区流二段发育了一定规模的滨浅湖滩坝砂体。在滩坝砂体沉积特征分析的基础上,利用地震沉积学分析方法和技术,对滩坝砂体分布规律及演化特征进行了研究。在沉积模型控制和钻井资料标定的基础上,地层切片属性分析能够较好的反映滩坝砂体的分布范围,并且能够较好的对坝砂和滩砂沉积进行区分和识别。地层切片分析表明MC1旋回内滩坝砂体早中期表现为进积特征,滩砂和坝砂沉积范围均明显扩大和迁移,中晚期表现为加积特征,坝砂厚度和范围明显增加;MC2旋回内滩坝砂体沉积过程中分布范围变化不大,滩砂和坝砂均呈明显的垂向加积特征。两个旋回内坝砂沉积主要呈相互平行的条带状分布在研究区东南部及中部。为了增加钻井成功率和探明滩坝砂体主体发育特征,建议目前的勘探重点应放在研究区东南部及中部坝砂沉积发育区。     

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。     

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.     

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。     

‘Earth system governance’ as a crosscutting theme of global change research

In 2001, the four global change research programmes ‘urgently’ called for ‘an ethical framework for global stewardship and strategies for Earth System management’. Yet this notion of ‘earth system management’ remains vaguely defined: It is too elusive for natural scientists, and too ambitious or too normative for social scientists. In this article, I develop an alternative concept that is better grounded in social science theory: ‘earth system governance’. I introduce, first, the concept of earth system governance as a new social phenomenon, a political programme and a crosscutting theme of research in the field of global environmental change. I then sketch the five key problem structures that complicate earth system governance, and derive from these four overarching principles for earth system governance as political practice, namely credibility, stability, adaptiveness, and inclusiveness. In the last part of the article, I identify five research and governance challenges that lie at the core of earth system governance as a crosscutting theme in global change research. These are the problems of the overall architecture of earth system governance, of agency beyond the state, of the adaptiveness of governance mechanisms and of their accountability and legitimacy, and of the modes of allocation in earth system governance—in short, the five A's of earth system governance research.