分层伸展叠加变形二维离散元模拟

分层伸展叠加变形是裂陷盆地演化过程中普遍存在的一种复杂的构造地质现象,是裂陷盆地构造地质研究和油气成藏研究的热点。目前有关分层伸展叠加变形的研究仍处于几何学描述阶段,缺乏对其动力学演化过程的解析。本文采用构造地质研究领域中新兴的模拟方法——离散元,通过构建离散元模型模拟研究分层伸展叠加变形的断裂发育过程。结果表明:(1)上下两套伸展断裂系统之间是否存在韧性滑脱层(泥岩层或膏岩层)是分层叠加变形的主控物质因素;(2)中间韧性地层隔断了下部断层向上的继承性发育,从而形成上下两套断裂系统分层伸展,垂向上叠加的变形特征;(3)受韧性地层侧向牵引作用影响,上部断裂系统的横向展布明显扩大;(4)在相同岩性条件下,降低伸展速度会显著降低两侧断层发育的差异性,但不会改变垂向上分层伸展的变形特征。研究解析了分层伸展叠加变形的动力学演化过程,有助于进一步认识分层伸展叠加变形机制及其对油气运聚成藏的控制作用。     

酸性火山事件粘土层和放射性测量在地层时间对比中的应用

酸性火山事件所形成的粘土岩称之为火－残粘土岩。目前已发现有伊利石－蒙脱石粘土、富钾伊利石“绿豆岩”、“大同黑砂石”（微晶高岭岩）、膨润土矿或蒙脱石粘土岩等４种类型，此外，还有火－沉硅质岩。虽然火－残粘土岩的外貌难以辨认，但因其中含继承性很强的Ｔｈ，Ｕ，＾４０Ｋ，Ｔｉ等元素，因此可利用地球化学研究方法、方射性测量和γ测井将其查明。上述各类型的火－残粘土岩及火－沉硅质岩的γ测井曲线各具特征，不仅可以识     

Discrete Element Modeling of Drop Tests

A discrete element code with impact model has been developed and calibrated to simulate the dynamic behavior of rock materials, with special regard to rock fragmentation upon impact during rock-fall analysis. The paper summarizes the discrete element code, the calibration algorithms developed to identify the model microparameters, and the impact model. Experimental work on drop tests is then used to validate the code on modeling impact fragmentation. It has been found that the developed discrete element code and impact model can reasonably simulate rock fragmentation in drop tests. The use of the discrete element code and impact model can provide good reference results in evaluating impact fragmentation in rock-fall analysis.     

Finite Difference Implicit Structural Modeling of Geological Structures

We introduce a new method for implicit structural modeling. The main developments in this paper are the new regularization operators we propose by extending inherent properties of the classic one-dimensional discrete second derivative operator to higher dimensions. The proposed regularization operators discretize naturally on the Cartesian grid using finite differences, owing to the highly symmetric nature of the Cartesian grid. Furthermore, the proposed regularization operators do not require any special treatment on boundary nodes, and their generalization to higher dimensions is straightforward. As a result, the proposed method has the advantage of being simple to implement. Numerical examples show that the proposed method is robust and numerically efficient.

     

内蒙古大青山晚古生代煤系中火山事件层的物质来源及地层意义

在内蒙古大青山晚古生代煤系地层中发现了９层以上火山事件层，主要由凝灰熔岩、火山角砾岩、熔结凝灰岩、凝灰岩、沉凝灰岩及各种凝灰质沉积岩组成。通过剖面层序分析和岩石学、岩石化学、稀土元素和同位素比值研究，可将本区火山事件层划分为９个喷发旋回；根据火山事件层的分布，本区煤层可与山西大同同时代的煤层相对比；这一研究结果为大区域煤层对比提供了重要的科学依据。根据本区的研究工作并与内蒙海槽火山活动资料相对照，本区火山碎屑物质来自内蒙海槽钙碱性岛弧型火山活动的观点得到证实，也为华北板块与古亚洲洋板块之间的封闭机理，提供了新的资料。     

基于GMS的Solids建模地层的转化与修正方法探讨

地下水数值模拟软件GMS以其友好的界面、强大的处理功能和优良的三维可视效果受到人们的广泛的应用。建立Modflow模型有三种方法:网格法、概念模型法和Solids法,利用Solids法建立复杂地层模型能起到事半功倍的效果。针对不同的四种地层类型,论述了地层空间信息转化成Modflow模型中的顶底板标高步骤中关于地层转化和修正的方法。     

Discrete Element Modeling of Rock Fragmentation upon Impact in Rock Fall Analysis

A discrete element code has been used to simulate impact-induced rock fragmentation in rock fall analysis using a simplified impact model inspired by the theory of vibrations for foundations on elastic media. The impact velocity, the angle of incidence, pre-existing fractures, and the ground stiffness all play important roles in impact fragmentation. Based on the simulation results, impact fragmentation occurs locally at the impact zone without generating large fragments for a homogeneous rock block. Large fragments are generated only when there are open pre-existing fractures in the rock block or when there are fully persistent closed fractures. Softer ground tends to reduce the potential for impact fragmentation. Energy transformation and failure occur only during impact including approach and restitution stages. Friction energy loss accounts for most of the energy loss during the fragmentation process, while tensile cracking energy loss is not significant.     

基于正演分析的高阻抗地层下多次波压制技术

随着勘探程度的不断提高,勘探目标向着浅、深方向发展是我国东部老油田发展方向之一。在泌阳凹陷深凹区由于存在横向展布比较稳定的白云岩沉积,不仅屏蔽了地震信号能量的有效下传,而且造成了多次波的发育,加之深层系地层经强烈压实作用后,砂泥岩的速度、密度接近,没有较强的波阻抗界面,致使深层系地震资料的信噪比极低,极大地影响了构造解释和储层预测。在基于模型的多次波渐近射线法正演模拟结果基础上,搞清多次波的运动学和动力学特征,为多次波压制方法的选择提供依据,并提出相关的配套处理手段,提高深凹区白云岩高阻抗层下深层地震反射质量的处理水平。通过剔除拟合法去除多次波和能量补偿等手段,提高了泌阳凹陷深层系地震资料的信噪比和分辨率,取得了很好的勘探效果。      

裂缝密度约束的离散裂缝网络建模方法与实现

如何高效地用多种类型资料(如地震、测井、岩芯等)所得到的裂缝信息对离散裂缝网络建模至关重要。为此本文提出一种裂缝密度约束的离散裂缝网络建模方法,将多种裂缝先验信息转换为裂缝密度,通过密度约束裂缝网络模型。方法对裂缝位置的确定方法进行改进,从编程的角度对二维和三维实现进行了分析,同时讨论了方法的适用性及参数设定。为验证方法效果,实例分析部分选用鄂尔多斯盆地延河剖面附近的一井区数据进行裂缝建模,并与实际生产资料进行比对,结果表明该方法所建立的裂缝模型与实际生产数据吻合。     

Implicit Structural Modeling by Minimization of the Bending Energy with Moving Least Squares Functions

Mathematical Geosciences - In this paper, an implicit structural modeling method using locally defined moving least squares shape functions is proposed. The continuous bending energy is minimized...     

构造掀斜主导的断陷湖盆缓坡层序“源—汇”正演模拟定量研究

断陷湖盆缓坡带的构造掀斜作用对其地层叠置样式和沉积体系展布具有重要的控制作用。通过基于“源—汇”系统理论的地层正演模拟研究方法,在三级层序地层格架下（以2 Myr为总时长）对断陷盆地缓坡带构造掀斜型层序地层发育样式及其相关地貌演化、沉积物通量变化进行了定量表征。以恒定的绝对湖平面为研究前提,共建立了高/低沉积物供给的背景下4种不同的地层正演模型。两种不同缓坡带掀斜初始位移模型的设定反映了掀斜点和沉积滨线的相对位置,以便于不同掀斜层序样式对比分析。研究表明,掀斜支点位于滨线之上的模型常形成湖侵和正常湖退,而掀斜支点位于滨线之下的模型常形成强制湖退。滨线迁移轨迹和层序叠置样式的不一致性贯穿整个层序发育过程,是沉积物通量及滨线迁移共同作用的结果。该模型中沉积物通量的变化直接响应于源区地貌演变,滨线迁移则受控于新增可容空间和沉积物供给的相互关系。这一系列构造掀斜型层序模型及其相关成因解释对断陷盆地层序地层格架及其叠置样式的精细解剖具有重要的指导意义。该模拟研究对断陷湖盆的高频湖平面变化特征也有较为合理的解释（如海洋同位素3期以来的贝加尔湖）。然而本次正演模拟所设置的初始地貌较为单一,在相同构造、气候条件下和不同沉积物供给背景下所形成地层模型无法涵盖所有缓坡带层序地层类型。由此可见,基于“源—汇”系统思想探讨断陷盆地层序地层多样性的相关模拟工作仍然任重道远。     

Stratigraphic Framework of the Cryogenian in China

The Cryogenian is a critical period in the history of the Earth. It is marked by multiple extreme climate changes that caused alternating global glacial and interglacial intervals. These dramatically changed the sedimentary system, and metal ores and source rocks distributed widely during this period. Therefore, studying the Cryogenian stratigraphic framework and sedimentary basins is important to improve the stratigraphic resolution for metal mineral and hydrocarbon prospecting and exploration ...     

三维介质中探地雷达(GPR)波传播逐段迭代射线追踪方法研究和应用

基于F erm at原理和Sne ll定理对三维任意界面情况下的两点间GPR波传播射线追踪问题进行了研究,采用了一个适用于任意界面情况下计算反(折)射点的一阶近似公式,从任意给定的初始路径出发进行逐段迭代计算,给出了三维逐段迭代射线追踪算法的计算格式,并进行了三维介质下射线追踪计算。结果表明计算速度相当快,且其计算精度可以根据需要达到任意要求。在此基础上,根据雷达波传播规律,考虑每一段的能量损失。根据地质雷达的发射子波,最终获得三维介质中雷达波传播和接收记录。并将结果应用于实际剖面拟合中,提高了解释的精度。     

Reform essential in Rules of Stratigraphic Classification

A demonstration of substantial shortcomings in the rules of stratigraphic classification and terminology adopted in the USSR which are based upon an erroneous concept as to the existence of a single stratigraphic scale. The need for a concurrent development of two independent stratigraphic scales, the international (biostratigraphic) and the regional (essentially lithostratigraphic) is demonstrated by specific examples of studies of new regions in Siberia.--Authors     

Sequence Stratigraphic Modeling of Sedimentary Basin: Conceptual Model and Application to Erlian and Yinggehai Basins, China

INTRODUCTIONQuantitativebasinmodelinghasbecomeoneofthefrontiersinsedimentarybasinanalySis.Alargevarietyofnumericalmodelsconcerningbasinformation,basinfillingprocess,thermalhistory,hydrocarbongenerationandaCCUmulationhavebeenformulatedoverthelastdecadetondAnctheprocessesandevollltionofsedimentarybasins(Mckenzie,1978,signeretal.,1990;Ungereretal.,1990).Thebasinmodeling,utilizingcomputersimulationtechnique,isapowerfultoolforbasinanalySisandhasincreasinglybeenintegratedintoconventionalbasi…     

The Uncertainty in the True End Point of a Fossil's Stratigraphic Range When Stratigraphic Sections Are Sampled Discretely

Stratigraphic sections are often sampled at well-defined discrete points. Because of the incompleteness of the fossil record, a particular species may not be observed even when it is extant at a sampling point. We introduce a model and Bayesian analysis for estimating the true time of disappearance of a lineage from a section in the face of the possibility that failure to find the species beyond its observed stratigraphic range may represent false negatives. We incorporate proper prior information, including an estimated longevity of the species and the probability that it will be observed if extant. Our analysis produces a posterior density for the true extinction time of the species. Summaries of this probability distribution provide a point estimate of the extinction time, a standard deviation for the uncertainty in the estimate, and confidence intervals for the time of extinction. We apply our model to stratigraphic ranges of benthic foraminifera collected from the early Late Cretaceous (Cenomanian and Turonian) from Eastbourne, England.     

离散裂隙渗流方法与裂隙化渗透介质建模

流体渗流模拟的连续介质方法通常适用于多孔地质体，并不一定适用于裂隙岩体，由于裂隙分布及其特征与孔隙差异较大。若流体渗流主要受裂隙的控制，对于一定尺寸的裂隙岩体，多孔介质假设则较难刻划裂隙岩体的渗流特征。离散裂隙渗流方法不但可直接用于模拟裂隙岩体非均质性和各向异性等渗流特征，而且可用其确定所研究的裂隙岩体典型单元体及其水力传导（渗透）张量大小。主要讨论了以下问题：（1）饱和裂隙介质中一般的离散流体渗流模拟；（2）裂隙岩体中的REV（典型单元体）及其水力传导（渗透）张量的确定；（3）利用离散裂隙网络流体渗流模型研究裂隙方向几何参数对水力传导系数和REV的影响；（4）在二维和三维离散裂隙流体渗流模型中对区域大裂隙和局部小裂隙的处理方法。调查结果显示离散裂隙流体渗流数学模型可用来评价不同尺度上的裂隙岩体的水力特征，以及裂隙方向对裂隙化岩体的水力特征有着不可忽视的影响。同时，局部小裂隙、区域大裂隙应当区别对待，以便据其所起的作用及水力特征，建立裂隙化岩体相应的流体渗流模型。     

Stratigraphic evidence of human disturbance in an estuary

Prior to European settlement, oligohaline and mesohaline sections of Chesapeake Bay draining Piedmont saprolite supported diverse and abundant diatom and macrophyte populations. Compositional changes in diatoms and macrophytes in oligohaline sections correspond with 17th- and 19th-century deforestation and increased siltation, while effects on downstream populations were less notable. After deforestation, previously sparse diatom populations in a mesohaline estuary draining sandy Coastal Plain soils became more abundant. Fertilization of cultivated land was accompanied by increased production of both attached and free-floating diatoms. After the discharge of sewage, diatom populations increased enormously in the affected areas, followed by a dramatic decrease. The decrease suggests silica limitation after intense phosphorus enrichment. The loss of macrophytes and increase in planktonic diatoms in oligohaline areas in recent years resemble the historical sequences observed in lakes undergoing eutrophication. However, in the estuary, similar declines have also occurred in macrophyte populations in mesohaline areas where eutrophication is much less severe, but where chlorine and herbicide toxicity during the past 20 yr is similar to upstream areas.     

陆相盆地层序构型多元化体系

不同于具有相对稳定构造-沉积背景海相盆地的层序构型,陆相盆地的层序构型具有多样性.针对陆相盆地具有局限、封闭、类型多样、控制因素多变、多物源、古地貌差异大等典型特征,提出"陆相盆地层序构型多元化体系"的观点."陆相盆地层序构型多元化体系"是指不同类型陆相盆地在多种因素综合作用下,会形成不同的层序构型、沉积充填样式,构成陆相盆地层序构型多元化体系.该体系包含经典层序构型和特征性层序构型两大类,在系统总结不同类型陆相盆地经典层序构型的基础上,进一步介绍断陷盆地非同步叠加、迁移型、陆内克拉通盆地"溯源退积"等多种新的特征性层序构型,补充、丰富了陆相盆地层序构型多元化体系.陆相盆地层序构型多元化体系反映了陆相盆地沉积动力学过程的复杂性,可以将不同类型陆相盆地所发育的不同层序构型纳入到一个统一体系,有利于陆相层序地层学研究的系统化,丰富陆相盆地层序地层理论体系.      

依-舒地堑下第三系地层格架与成因单元

依-舒地堑是大庆油田的主探区之一,下第三系是主要勘探目的层,准确地建立地层格架是油气勘探的基础。在占有大量资料的基础上,采用数理统计分析方法,建立了测井曲线、微量元素分层模式,有效地解决了测井曲线局部干扰和地层分析实验样品量少的问题。在综合考虑6种因素的基础上,以生物层序和构造层序单元为基础,建立了依-舒地堑的整体地层格架,提出了依-舒地堑统一地层格架对比方案,指出T₅、T₃、T₁地震反射层具有构造旋回意义,代表盆地演化的不同阶段,T₄、T₂地震反射层具有沉积学以及气候层序的意义。