断层相关褶皱对砂岩构造裂缝发育的控制约束

在砂岩储层中进行构造裂缝发育规律的研究,对储层预测具有一定的现实意义。文中以库车坳陷东部地区砂岩中发 育的断层转折褶皱和断层传播褶皱为研究对象,统计分析构造裂缝密度大小与断层距离的关系,探讨断层相关褶皱对裂缝 发育程度的规律性认识。分析结果发现:在断层相关褶皱中,构造裂缝的密度随着距断层距离的增大而减小,二者存在明 显的指数关系;并且在靠近断层和转折端的附近,存在一个构造裂缝密度骤减的范围,定义这个范围为“断层 - 转折端共 控构造裂缝带”。断层相关褶皱带内“断层 - 转折端共控构造裂缝带”的发现与认识,对构造裂缝的定量化研究以及油藏数 值模拟等都具有一定的指导意义。     

断层转折褶皱剪切裂缝发育模式探讨

围绕库车前陆盆地内某典型断层转折褶皱剖面,实测统计该剖面不同构造部位的剪切裂缝,分析断层转折褶皱中剪切裂缝的发育规律,进而建立断层转折褶皱剪切裂缝的发育模式。统计结果表明,研究区剪切裂缝有2种类型,一类是与岩层面高角度相交的高角度缝,广泛发育在构造各个部位;另一类是与层面近于平行的顺层裂缝,主要发育在断层面附近,并随岩层的变形,产状发生改变。远离断层面,剪切裂缝发育程度整体上呈减小趋势,下盘裂缝发育强度的减小大于上盘,上盘裂缝发育强度整体大于下盘。褶皱内层剪切裂缝较外层发育,褶皱两翼裂缝发育强度大于褶皱枢纽。断层产状的改变,会引起上盘运动状态的改变,使得在上盘活动轴面附近出现应力集中,局部剪切裂缝发育强度出现增大现象。断层转折褶皱剪切裂缝的发育模式可以分为3个阶段,断层形成前主要发育与层面高角度相交的区域性剪切裂缝;断层形成初期,断层面附近两盘牵引变形不明显,上盘穿过断坡下部破折点处活动轴面的部分会产生新的剪切裂缝,即与岩层高角度相交剪切缝和与断层面低角度相交剪切缝;牵引构造明显时,断层面附近两盘弯曲部位会产生顺层剪切裂缝,两翼的裂缝发育强度大于枢纽。      

塔里木盆地玉北地区奥陶系储层构造裂缝成因模式

在基于成像测井、岩心及薄片资料对玉北地区构造裂缝进行识别并总结其发育规律的基础上, 根据裂缝切割关系、充填方解石阴极发光及包裹体特征划分裂缝发育期次, 并应用有限元法数值模拟不同裂缝发育期古构造应力场特征, 结合裂缝发育力学机制, 分析不同时期断层-褶皱控制下的裂缝成因模式。研究结果表明, 玉北地区奥陶系构造裂缝主要沿高陡带发育, 其发育程度、产状受断层、褶皱共同控制, 共发育4期裂缝, 其中加里东中期Ⅰ、Ⅲ幕裂缝受断层主控、加里东晚期至海西早期裂缝受断层与褶皱共同控制、海西晚期裂缝主要受褶皱控制; 与断裂走向较一致的高角度裂缝对储层发育贡献最大, 加里东晚期-海西早期及海西晚期两期裂缝发育区, 更有利于油气聚集。      

库车前陆冲断带低渗砂岩的裂缝发育模式

致密砂岩是重要的非常规储层,其裂缝的发育程度影响了储集性和渗透性。本文以库车坳陷北部野外裂缝测量和统计分析为例,研究前陆冲断带致密砂岩区裂缝发育的规律。提出前陆冲断带的构造裂缝可以分为三期:前褶皱期、同褶皱期和后褶皱期。根据每个实测剖面各测量点裂缝密度的测量统计分析,并与逆断层及相关褶皱的构造要素,如距断层或褶皱轴面的距离,开展回归分析,分别半定量地建立了逆断层及相关褶皱控制裂缝发育的模型,提出两种成因的构造裂缝,即"局部构造控制的裂缝带"和"区域构造裂缝"。前陆冲断带内局部构造控制的裂缝发育带具有上盘裂缝比下盘发育,背斜顶部和陡翼的裂缝比缓翼和远离断层区域更发育的特点。     

碳酸盐岩构造裂缝发育模式探讨

从影响碳酸盐岩构造裂缝发育的主要因素入手,结合研究实例解剖分析,分别从岩性、层厚、风化作用、断裂作用、褶皱作用和区域构造应力场以及热液改造7个方面探讨了各种因素如何控制构造裂缝的发育程度和分布规律,并提出各种因素分别控制裂缝发育的概念模型。在考虑单一条件下,认为较粗粒的碳酸盐岩比较细的碳酸盐岩更易发育裂缝;薄层比厚层更易发育裂缝;风化壳顶部比下部更易发育裂缝;断裂附近比远离断裂更易发育裂缝;褶皱的转折端比翼部更易发育裂缝;区域应力场的应力集中部位更易比其他地区发育裂缝。热液改造裂缝可分为水力作用型和后充填型。     

松辽盆地朝阳沟油田储层裂缝发育特征及控制因素

裂缝是朝阳沟油田储层的有效储集空间和主要渗流通道,其复杂分布严重影响该油田的开发生产。通过区域构造研究与岩心构造解析,结合地表露头和薄片观察,分析了区内裂缝的发育特征、成因机制及控制因素。该储层主要发育近SN向、近EW向、NW向和NE向4组构造裂缝,裂缝以低角度裂缝为主,主要包括挤压褶皱作用下形成的顺层滑脱裂缝和与逆冲挤压作用有关的低角度剪切裂缝,高角度裂缝主要包括扩张裂缝和中高角度斜缝。裂缝的充填及含油性表明它们大部分为有效缝,并反映在地层条件下的储渗作用。明水组沉积末期的反转构造期是裂缝的主要形成时期,主要形成近SN向和近EW向构造裂缝。裂缝的发育程度受岩性、层厚、断层、褶皱、深度等因素的控制,不同岩性,裂缝发育程度也不同;裂缝的平均间距与裂隙化的岩层厚度呈较好的线性相关关系;绝大多数构造裂缝与断层作用相关;褶皱的不同形成阶段发育不同类型的裂缝;随深度增加,裂缝发育程度明显降低。     

川东北巴中—通南巴地区须家河组致密砂岩储层裂缝发育特征及控制因素

以岩芯及野外观察、分析测试、测井等资料为基础,分析了川东北巴中—通南巴地区致密砂岩储层裂缝的类型及成因,结合裂缝充填矿物包裹体分析,厘定裂缝形成期次。在此基础上,探讨了岩性组合、岩层厚度、断层、褶皱变形强度对裂缝发育的控制作用。研究表明:研究区须家河组裂缝具有多成因、多期次、差异分布的特点。主要发育构造裂缝,且主要分布于致密砂岩储层中,可划分为3期:燕山中期(中侏罗世)的NNW和NWW向共轭构造缝,被细粒方解石充填;燕山晚期(白垩纪)的NE向断层、褶皱伴生高角度缝,被粗粒方解石或石英充填;喜马拉雅期(古近纪)的NW和近SN向断层伴生缝,被粗粒方解石半充填或未充填。成岩裂缝和超压裂缝的成因与黏土矿物失水收缩及烃源岩大量生烃引起的流体增压有关,主要形成时间为晚侏罗世—早白垩世。裂缝发育的差异性主要受控于岩性组合、地层厚度、断层及褶皱变形强度,单层厚度小、距断层距离近、褶皱变形强度大的中、细砂岩储层,裂缝最为发育。     

断层相关裂缝定性识别：原理与应用

介绍一种定性识别和预测断层相关裂缝的新方法-断面脱空法。该方法以断面脱空理论为基础,通过建立断面脱空空间与断层相关裂缝之间的置换模型,从而实现通过观察断层形迹开展地下断层相关裂缝的定性识别。以塔中Ⅰ号断裂带西侧中古3、塔中72两个井区下奥陶统良里塔格组（O₃l）为例,基于地震资料分别开展剖面和平面上的断层相关裂缝识别,并将预测结果与钻井、测井及地震属性分析获得的裂缝发育特征进行对比研究。结果表明:利用断面脱空原理预测结果与钻测井揭示结果基本一致,与根据均方根检测的裂缝平面分布对比,细节上有差异,但总体特征基本一致,表明利用断面脱空原理可以定性地对断层相关裂缝做出预测。断面脱空理论的提出不仅为定性评价地表、地下断层相关裂缝发育分布规律提供一种新思路,更为定量表征断层相关裂缝提供重要的理论依据。     

构造物理模拟和PIV有限应变分析对构造裂缝预测的启示

油气储层中构造裂缝发育与有限应变状态关系密切,为了探索有限应变分析与构造裂缝预测的新技术方法,此次研究设计完成了一组单侧挤压收敛模型的物理模拟实验,并引入粒子图像测速(PIV,Particle Image Velocimetry)技术对实验过程进行了定量化分析。实验模型在垂向上为含粘性层的多层结构,实验结果形成了一个肉眼可见的箱状褶皱。通过PIV技术可以获取实验模型变形演化过程中各阶段的位移场数据,计算出各阶段的增量应变,实现从初始状态到褶皱形成之后整个变形过程的有限应变分析,探讨构造裂缝成因机制和分布规律,进行定量化裂缝预测。挤压变形过程初期,应变分布范围很广,有限应变较弱(约4%~8%),在挤压方向上的线应变表现为弱压应变,在垂向上的线应变表现为弱张应变,这种现象是褶皱和断层产生前平行层缩短和层增厚的纯剪变形结果,也是区域型张裂缝和剪裂缝形成的主要机制。褶皱和断层即将发育之时至发育之后,应变局限在断层发育的剪切带及附近区域,有限应变表现为较强(达20%)的剪切应变和剪切张应变,是断层面附近简单剪切变形作用的结果,也是局部型剪裂缝和张剪裂缝形成的主要机制。     

断层相关褶皱理论与应用研究新进展

自Rich(1934)提出断层转折褶皱的几何学概念以来,Suppe(1983)首次将其定量化,建立了褶皱形态与断层形态和断层滑动之间的定量关系,奠立了断层相关褶皱理论的基本模型。20年来,不但建立了断层传播褶皱、断层滑脱褶皱等基本端员类型的几何学与运动学模型,也建立与完善了断层相关褶皱叠加样式的几何学与运动学模型,例如叠瓦构造、构造楔与干涉构造等。研究同构造沉积作用,建立了生长断层相关褶皱的几何学与运动学模型,将沉积作用与断裂作用、褶皱作用及构造隆升作用等有机地联系起来。考虑地层的力学性质与变形差异,提出与建立了剪切断层转折褶皱理论,并建立了断层相关褶皱的一系列力学模型。20年来,断层相关褶皱的基本研究方法经历了由二维剖面与平面分析向全三维空间分析的转变,由几何学、运动学模型向力学模型的转变,实验模拟技术与数值模拟技术在断层相关褶皱理论模型的建立与检验中发挥了重要作用。断层相关褶皱的理论和方法在工程地质、地震灾害预报与油气勘探开发等领域获得了广泛的应用。中国在天山、祁连山和龙门山等相邻的前陆盆地的活动构造与含油气圈闭研究中,应用断层相关褶皱的理论与方法取得了重要进展。     

Kinematic significance of fold- and fault-related fracture systems in the Zagros mountains, southern Iran

Initiation and formation of folds and the Kazerun high-angle fault zone, in the Zagros fold-and-thrust belt, were related to the continuing SW–NE oriented contraction that probably initiated in the Late Cretaceous, and intensified, starting in Miocene, when the Arabian and Eurasian plates collided. The contraction that led to folding and thrusting of the Phanerozoic sequence in the belt has led to the strike–slip reactivation of basement faults that formed during the Precambrian. Two major systems of fractures have developed, under the same regional state of contraction, during the folding and strike–slip faulting processes. Folding led to the formation of a system of fold-related fractures that comprises four sets of fractures, which include an axial and a cross-axial set that trend parallel and perpendicular to the confining fold axial trace, respectively, and two oblique sets that trend at moderate angles to the axial trace. Slip along high-angle, strike–slip faults formed a system of fractures in the damage zone of the faults (e.g., Kazerun), and deformed folds that existed in the shear zone by rotating their axial plane. This fault-related fracture system is made of five sets of fractures, which include the two sets of Riedel shear fractures (R and R′), P- and Y-shear fractures, and an extensional set.

Remote sensing analysis of both fracture systems, in a GIS environment, reveals a related kinematic history for folding outside of the Kazerun shear zone and faulting and deformation (fracturing and rotation of folds) within the Kazerun fault zone. Rotation of the folds and formation of the five sets of the fault-related fractures in the Kazerun shear zone are consistent with a dextral motion along the fault. The mean trends of the shortening directions, independently calculated for the fold- and fault-related fracture systems, are remarkably close (N53 ± 4°E and N50 ± 5°E, respectively), and are perpendicular to the general NW–SE trend of the Zagros fold-and-thrust belt. Although segments of the Kazerun fault are variably oriented within a narrow range, the angular relationships between sets of fault-related fractures and these segments remain constant.     

Effect of initial fault geometry on the development of fixed-hinge, fault-propagation folds

This paper describes how a model of fixed-hinge, basement-involved, fault-propagation folds may be adapted to apply to thin-skinned thrust faults to generate footwall synclines. Fixed-hinge, fault-propagation folding assumes that the fold-axial surfaces diverge upwards, fold hinges are fixed in the rock, the fault propagated through the forelimb, thickness changes occur in the forelimb and the forelimb progressively rotates with increasing displacement on the underlying fault. The original model for fixed-hinge, fault-propagation folds was developed for the case of a planar fault in basement with a tip line that was at the interface between basement and the overlying sedimentary cover rocks. The two geometries applicable to thin-skinned thrusts are for the cases where a fixed-hinge fault-propagation fold develops above an initial bedding-parallel detachment, and an initial fault ramp of constant dip which flattens down-dip into a bedding-parallel detachment.     

龙门山南段邛西断层转折褶皱磁组构及其有限应变

龙门山南段位于四川盆地以西,其新生代构造变形特征对于认识青藏高原东缘的变形机制具有一定的指示意义。磁组构是一种灵敏的应变指示计,在变形微弱的沉积岩地区尤为适用。在龙门山南段邛西断层转折褶皱不同构造部位选取48个采样点开展磁组构研究,分析断层转折褶皱的有限应变特征及区域构造变形机制。实验结果表明,邛西地区上白垩统中主要载磁矿物为高矫顽力的赤铁矿,背斜整体应变较弱,且存在3种类型的磁组构,以沉积磁组构和初始变形磁组构为主,铅笔状磁组构少见,主要存在于靠近褶皱中段的前翼部位,说明断层转折褶皱前翼较后翼和核部应变强,且中段地层应变较其他部位更为强烈。此外,各采样点磁线理的优势方位为近南北向(N10°E),表明邛西断层转折褶皱的形成与龙门山南段晚新生代近东西向的地壳水平缩短有关,暗示龙门山南段的最大主压应力方向在晚新生代存在转变的可能。     

逆断层控制构造裂缝发育的力学机制模拟

在探讨逆断层对构造裂缝控制作用的基础上, 应用Comsol有限元软件, 模拟不同水平作用力、不同岩性、不同断层倾角和距断层面远近等因素影响下断层及其周边区域的应力、应变情况, 并分析了不同控制因素下构造裂缝发育的规律。模拟结果表明, 构造裂缝的发育程度随施加的水平应力作用增大而线性增大; 岩石破裂前产生的应变量可用来描述岩石的脆性, 抗压强度对岩石破裂起主导作用, 而岩石的抗剪强度与岩石破裂发育有一定的相关性; 逆断层倾角存在一个临界角度, 使构造裂缝发育最为强烈; 逆断层控制裂缝发育, 距离断裂面越远裂缝发育程度越低, 并存在一个发育程度骤减的范围, 称为"断裂控制带", 该断裂控制带的形成和分布应该与断裂的性质、规模、断距及岩石力学参数等有关。      

龙门山南段邛西断层转折褶皱磁组构及其有限应变

龙门山南段位于四川盆地以西,其新生代构造变形特征对于认识青藏高原东缘的变形机制具有一定的指示意义。磁组构是一种灵敏的应变指示计,在变形微弱的沉积岩地区尤为适用。在龙门山南段邛西断层转折褶皱不同构造部位选取48个采样点开展磁组构研究,分析断层转折褶皱的有限应变特征及区域构造变形机制。实验结果表明,邛西地区上白垩统中主要载磁矿物为高矫顽力的赤铁矿,背斜整体应变较弱,且存在3种类型的磁组构,以沉积磁组构和初始变形磁组构为主,铅笔状磁组构少见,主要存在于靠近褶皱中段的前翼部位,说明断层转折褶皱前翼较后翼和核部应变强,且中段地层应变较其他部位更为强烈。此外,各采样点磁线理的优势方位为近南北向（N10°E）,表明邛西断层转折褶皱的形成与龙门山南段晚新生代近东西向的地壳水平缩短有关,暗示龙门山南段的最大主压应力方向在晚新生代存在转变的可能。     

伸展断层相关褶皱的几何学分析及其在车镇凹陷中的应用

本文总结了伸展断层相关褶皱的发育类型,主要包括伸展断层传播褶皱与伸展断层转折褶皱(也叫断弯褶皱)等.伸展断层传播褶皱多形成在较陡的正断层之上,正断层向上传播使断层顶部地层弯曲,进而形成一个伸展的断层传播褶皱,其发育模式与三剪变形发育模式一致.车镇凹陷是渤海湾盆地南部一个典型的中新生代半地堑盆地.本文通过对横穿车镇凹陷的...     

Tectonic implications of damage zone-related fault-fracture networks revealed in drill core through the Nojima fault, Japan

1800 m of drill core through the Nojima fault zone, Japan, reveals subsidiary fault and fracture networks that developed in the fault zone that triggered the 1995 Ms 7.2 Kobe earthquake. The subsidiary fault zones contain a fault gouge of < 1 cm bounded by thin zones of foliated cataclasite or breccia. Fractures are filled with calcite veins, calcite-cemented breccias, clay, and iron-oxide and carbonate alternation of the granitic host rock. These features are typical of extensional fractures that form the conduit network for fluid flux close to a major fault zone. The zone of distributed deformation surrounding the main fault is 50 m in width, and the dip of the Nojima fault at > 1 km depth is 75°. The fault-fracture networks associated with the Nojima fault zone are coseismic and were filled with carbonate and fine-grained material during repeated seismic-related infiltration of the fault zone by carbonate-bearing subsurface water. This study shows that fault-related fracture networks plays an important role as fluid flow conduits within seismically active faults, and can change in character from zones of high permeability to low permeability due to cementation and/or pore collapse.     

Faults and their associated host rock deformation: Part I. Structure of small faults in a quartz–syenite body,southern Israel

We analyze pervasive and discontinuous deformation associated with small faults in a quartz–syenite body in southern Israel. The analysis includes detailed mapping, measurement of in-situ mechanical rock properties and microstructural study of the faults. The mapped faults have 1–100-m-long horizontal traces, consisting of linked, curved segments; the segmented nature of the faults is also apparent at the 1–10 mm scale. The observed deformation features are breccia, as well as intra- and inter-granular fractures; these features are accompanied by reduction of the Young modulus and uniaxial strength of the host rock. The deformation features are zoned from a central fault-core through a damage-zone to the protolith at distances of 0.05–0.06 the fault length. Shear strains up to 300% were calculated from measured marker lines displacements and distortion in proximity to the faults. We argue here that the fault-related deformation during fault propagation is manifested by highly localized deformation in a process zone having a width of 0.001–0.005 of the fault length (fault-related deformation due to subsequent slip along the existing faults is analyzed in Part II). The observed self-similarity of the discontinuities over five length orders of magnitude and the outstanding lack of tensile microcracks suggest fault initiation and growth as primary shear fractures.