浙西北前陆褶皱冲断带特征及上古生界含油气性

主要通过对晚工及中生代地层的岩石组合、岩相及构造牲的分析，认为浙西北地区直到早三叠世仍为一倾向东南的被动大陆边缘，中三叠世到白垩纪主要发育前陆磨拉石沉积；板块碰撞始于旱三叠世晚期，逆冲推覆冲席为浙西北地区的主要构造形式，推覆方向自南东向北西。浙西北地区残存的晚古生代地层中油气显示比较普遍，表明该区有一定油气探前景。该区晚古生代海相地层中的３套生储盖组合相互配套，其中油源岩在早、中侏罗世进入成熟阶段     

南天山库车褶皱冲断带的伸展构造

为利于库车地区天然气的勘探与开发,对该区构造提出了一些不同的认识。通常认为,自渐新世晚期至今,南天山库车地区一直处于南北向挤压构造环境。但实地考察发现,新生界地层不仅被推覆构造卷入,而且亦有受到南北向拉张构造的改造,发育有5种伸展构造:挤缩地质体后部的块断伸展构造(块断构造)、挤缩地质体的反向伸展构造(反向正断层)、挤缩地质体的横向伸展构造(横向正断层)、挤缩地质体的反转伸展构造(负反转构造)、挤缩地质体隆起部的裂陷伸展构造(正地堑)。收缩与拉伸构造的关系表现为,在同一地段,早时挤缩褶冲,后时伸展块断,先后复合;在同一时段,前缘挤缩冲断,后缘伸展正断,前后并列。南天山构造地貌景观表明,通常被否定的我国西北地区含油气盆地的伸展构造是实在的,且与推覆构造相随相伴,这对于该区推覆构造控气与伸展构造调气的分析评价具有实际意义     

THE CONFIGURATION OF THE BASEMENT BENEATH THE ZAGROS BASIN

It has long been recognised that the deposition and deformation of the Phanerozoic cover in the Zagros Basin (mountains plus foreland) was strongly influenced by the reactivation of old tectonic fabrics in its basement. Facies boundaries and structures trending north-south and NW-SE can be attributed to the reactivation of Pan-African sutures and Najd faults which are exposed in the Nubian-Arabian Shield. However, to the east of a projection of the Oman line SWwards into the Rhub Al Khali Basin, cover structures have a NE-SW trend which is not seen in Arabia. This boundary may overlie a Pan-African suture between Arabia and India (Somalia or Pakistan).
Data including magnetic intensities, geothermal gradients and isopach maps are used here to distinguish old faults which were reactivated in the basement from more recent faults formed in the cover by Zagros shortening. Old faults trending NW-SE are interpreted as having reactivated episodically since the Permo-Triassic opening of Neo-Tethys; perhaps more significantly, the basement faults that reactivated in the East Arabian Block since then trend north-south. The basement configuration is clarified by extending a modified East Arabian Block across the Zagros to an "East Arabian-Zagros block" in which the NW trend of the Zagros lies between two syntaxes. This suggests a new tectonic framework for the region. The repeated reactivation of basement faults throughout the East Arabian-Zagros Block controlled source rocks, traps and seals for the supergiant and giant oil and gas reserves which are present at various stratigraphic levels in different areas.     

STRATIGRAPHIC CORRELATION AND SOURCE ROCK CHARACTERISTICS OF THE BALUTI FORMATION FROM SELECTED WELLS IN THE ZAGROS FOLD BELT,KURDISTAN REGION,NORTHERN IRAQ

The Upper Triassic Baluti Formation has been identified and mapped based on its log response in selected wells from the Zagros foldbelt in the Kurdistan Region of northern Iraq. A preliminary evaluation of the formation's source rock potential was made by Rock-Eval screening analysis in four wells along a NW-SE profile (Atrush-1, Shaikan-5B, Taq Taq-22 and Miran-2) with maturity determined from reflectance measurements in samples from well Taq Taq-22. The Baluti Formation consists of thinly interbedded shales, carbonates and anhydrite ranging in thickness from 48 m in well Atrush-1 to 118 m in well Miran-2. The Rock-Eval screening was conducted primarily on bulk cuttings samples plus selected picked cuttings. The TOC content is low to moderate (0.23 to 1.14 wt%). However, the shale content in many of the analysed bulk samples was relatively low, making assessment of the source potential problematic. The highest TOCs are recorded from the thickest analysed sections from wells Miran-2 and Taq Taq-22, where high-gamma bituminous shales are present. Rock-Eval T_max values ranging from 295 to 438°C are not consistent with estimates of pre-Zagros burial to depths of between 4600 m (Atrush-1) and 6900 m (Miran-2). The relatively low T_max values suggest that the S2 response does not reflect kerogen pyrolysis in these samples and may be due to the presence of solid bitumen, which is observed in the Baluti Formation in at least three of the study wells (Taq Taq-22, Miran-2 and Shaikan-5B). Little pyrolysable organic matter remains in the formation due to the interpreted deep pre-Zagros burial and the consequent high maturity in Taq Taq-22 (VR = 1.51%R_o) and Miran-2 (estimated VR >2%R_o), and the poor source character in Atrush-1 and Shaikan-5B. Organic petrography suggests the presence of vestiges of Types I and II kerogen in Taq Taq-22, with bitumen observed as stains in the matrix of the shales and also in the pores and fractures of interbedded dolostones. However, bitumen reflectance determinations for Taq Taq-22 indicate an equivalent vitrinite reflectance maturity of no more than 0.93%R_o, which is significantly less than that of the indigenous vitrinite, implying the solid bitumen in this well is derived primarily from migrated hydrocarbons. Further detailed analysis is required, but the results suggest that the Baluti Formation may have sourced hydrocarbons in its depocentre which is identified in this study as covering a NW-SE trending area between Bekhme and Sangaw.     

THE EFFECT OF BASEMENT FAULTING ON DIAPIRISM

Experimental and natural examples illustrate the influence of sub-salt horizon basement faults on diapirism. In a series of experimental models, viscous diapirs were observed to form above or close to basement faults. In all the models, basement faults initiated a half-graben, where thicker overburden units enhanced differential loading on an underlying buoyant layer. The buoyant material flowed updip to the low-pressure zones in the uplifted block, and updip along the tilted upper boundary of the hanging-wall. Basement faulting extended the overburden, and provided the space through which the buoyant layer could rise. Subsidence and faulting of overburden layers allowed diapirism along the faulted zones. In all cases, the deformation in the overburden was accommodated within a wider zone of faulting than the discrete basement fault which initiated the deformation. Differential compaction enhances differential loading and accumulation of thicker overburden on the downthrown sides of basement faults.
Seismic profiles from the Danish Basin, Dutch Central Graben, Gulf of Mexico and North Sea show that diapirs are spatially associated with basement faults. However, model results show that diapirs triggered by basement faults are not necessarily located directly above the faults.
Basement faults extend the cover sequences. If detached from the cover by a ductile layer, thick-skinned extension is accompanied by thin-skinned extension and decoupling of the cover. The influence of basement faults on diapirs depends on: the thickness and effective viscosity of the ductile layer (e.g. rock salt); the thickness ratio between the buoyant layer and the overburden; the mechanical properties of the brittle cover in the case of clastic sediments; the rate of sedimentation; the displacement rate throw and the dip of the basement faults.     

黄骅坳陷徐杨桥-黑龙村潜山带逆冲构造的发现及其意义

利用研究区高品质的地震资料和测井资料,解释出了数条逆冲断层,重点分析了黄骅坳陷徐杨桥 -黑龙村潜山带逆冲构造的分布、几何特征、成因及发现逆冲构造的意义。这些逆冲断层具有切割深、断距大、剖面宽度大的特点。徐杨桥-黑龙村潜山带逆冲断层形成于燕山早期,郯庐断裂左行走滑是断层形成的主要动力。     

BASIN EVOLUTION OF THE LURESTAN REGION IN THE ZAGROS FOLD-AND-THRUST BELT, IRAN

The evolution of the central part of the Lurestan region in the Zagros fold-and-thrust belt has been studied using newly generated isopach maps for different time intervals between the Late Cretaceous and the Miocene. The study was based on existing geological maps, gravity data, measured stratigraphic surface sections, original field work and well data. Understanding the processes which have influenced facies and thickness variations in the study area will have a significant impact on future hydrocarbon exploration.
Cenomanian carbonates assigned to the Sarvak Formation, the main reservoir unit in the study area, are composed of both pelagic and neritic facies. These facies occur along the roughly north-south trending "Anaran lineament", interpreted to represent a palaeohigh, which influenced patterns of sedimentation in the Cretaceous-Tertiary. The palaeohigh formed as a result of the reactivation of a basement lineament in the Late Cretaceous. The continuing influence of this lineament on patterns of sedimentation during Oligocene — early Miocene time is indicated by a range of evidence including the presence of clinoform geometries.
Analysis of sedimentary thicknesses in the Zagros foreland basin between the Late Cretaceous and the early Miocene indicates progressive SWward migration of the depocentre. Late Cretaceous ophiolite obduction and plate margin convergence exerted a major influence on stratigraphic architecture, and controlled depocentre migration and foreland basin evolution.     

TECTONO‐STRATIGRAPHIC EVOLUTION OF THE NW SEGMENT OF THE ZAGROS FOLD‐THRUST BELT,KURDISTAN, NE IRAQ

The Kurdistan (NW) segment of the Zagros fold‐thrust belt, located in the Kurdistan Region of NE Iraq, forms the external part of the Zagros orogen and is bounded by the Zagros suture to the NE. To the SW is the Arabian Plate into which the deformation front has migrated progressively, beginning in the Late Cretaceous and culminating in the Tertiary. Regional compression resulted in obduction of the Mawat ophiolites and emplacement of the Avroman and Qulqula nappes onto the continental margin, and the formation of the Kurdistan foreland basin. In this paper, structural, stratigraphic and palaeontological data together with new field observations are used to investigate the tectono‐stratigraphic evolution of this basin, and to study the propagation of the deformation front from the Zagros Imbricate Zone in the NE towards the Mesopotamian foredeep in the SW. Six unconformities within the Kurdistan foreland basin succession are recognized: Turonian (base‐AP9; 92 Ma); Danian (base‐AP10; 65 Ma); Paleocene–Eocene (intra‐AP10; 55 Ma); late Eocene (top‐AP10; 34 Ma); middle‐upper Miocene (a local unconformity; intra‐AP11; 12 Ma); and Pleistocene. These unconformities can be divided into two groups; obduction‐related (Turonian, Danian, and Paleocene‐Eocene); and collision‐related (late Eocene, middle‐upper Miocene, and Pleistocene). The geographical position of the unconformities is used to determine the rate of propagation of the deformation front, which is estimated at ca. 3 mm/yr. This is in agreement with previous studies which suggested a NW‐ward decrease in the propagation rate. The rate was most rapid (2.95 mm/yr) in the Low Zagros Fold‐Thrust Zone and slower (2.06 mm/yr) in the High Zagros Fold‐Thrust Zone. The more rapid propagation rate in the former area may be attributed to the presence there of the Miocene Lower Fars Formation which acted as a shallow décollement surface. Within the Zagros fold‐thrust belt, the intensity of deformation decreases towards the foreland (SW). Deformation in the High Zagros Fold‐Thrust Zone is characterized by thrust imbricates and high amplitude fault‐propagation folds at the surface separated by narrow synclines. However, the Low Zagros Fold‐Thrust Zone (Simply Folded Belt) is characterised by detachments and low amplitude fault propagation folds separated by broad synclines. In the foredeep area, folds are confined to the subsurface. Deeply buried Jurassic units, together with Upper Cretaceous – Paleocene siliciclastics, and the evaporite‐dominated Lower Fars Formation may have acted as décollement surfaces in the NW segment of the Zagros fold‐thrust belt, and controlled the structural geometry and evolution of the area.     

鄂尔多斯盆地西部逆冲推覆构造带特征及其演化与油气勘探

该带以青铜峡-固原断裂为界,以东为南北向构造带,以西为六盘山弧形构造带。逆冲带由一系列向东或北东逆冲的叠瓦状断层所组成,中生代是其主要形成和发育时期。本区含油远景以韦州-马家滩地区的原地岩体及南北向构造带的前缘外带北段为最好。     

库车再生前陆逆冲带的构造特征与成因

库车再生前陆逆冲带自北而南分为以下５个构造速：①北部边缘冲断－隐伏构造楔;②斯的克背斜带;③北部线性背斜带;④拜城背驮凹陷;⑤丘里塔格前缘带。全体形成前锋向南的冲断变形楔。各构造带中发育多种型式的断坪／断坡台阶状逆断层相关褶皱：断层传播褶皱滑脱褶皱、断层传播－滑脱混生褶皱、双重逆冲构造。在不同构造带发不同时代的生长地层,批示了各构造带不的构造变形年代。斯的克背斜带变形时期最早,始于中新世带的亚肯变     

苏德尔特潜山带元素地球化学特征及意义

海拉尔盆地苏德尔特潜山带是勘探突破的重要地区,储层普遍含有凝灰质,盆地改造强烈,断裂系统复杂,导致沉积和成岩环境复杂.通过对苏德尔特潜山带储层微量元素地球化学特征的综合分析和研究指出:w(v) /w (Ni)和w(Sr) /w (Ba)是2个重要的标志性微量元素地球化学特征参数;w (Sr) /w (Ba)大于1时水体变浅,w(V) /w (Ni)较高时富氧程度和酸度增加.结合w(Na2O)、w(K2O)和w(TFe)(全铁)的含油气储层元素分析结果和成岩黏土矿物分析结果指出:沉积期为偏酸性和氧化度较高的沉积环境,成岩期为偏碱性的碱性成岩作用环境,这一认识对苏德尔特潜山带储层的石油地质勘探具有重要意义.     

南天山前陆冲断带中段乌什-温宿地区构造分析与油气成藏

建立了乌什-温宿地区的地质结构模型,恢复了其新生代演化历史,探讨了油气远景。指出乌什-温宿地区由乌什凹陷和温宿凸起2个构造单元组成,乌什凹陷为具有挤压性质的断陷,温宿凸起为受基底卷入逆冲断裂控制的古隆起,构造样式侧向变化显著;该区新生代主要变形期为渐新世晚期-中新世早期和上新世-早更新世2期,水平挤压缩短量13～21km,缩短率14%～20%,平均变形速率0.56～0.9mm/a;受多旋回演化背景的控制,乌什-温宿地区形成多种有利的圈闭类型,具有早、晚两期成藏的特点。     

辽中南洼走滑反转带的形成及其对油藏的控制作用

走滑反转带对油气具有明显的控制作用。通过三维地震精细构造解释,结合钻井资料,分析了走滑反转带的形成机理及对油气成藏的控制作用。研究表明:断裂系统表现出右旋走滑性质,断裂的发育与里德尔右旋剪切模型相对应;走滑反转带的形成主要经历了4个阶段;渐新世时期,在右旋走滑挤压应力影响下,辽中南洼中央沿早期正断裂发生剧烈的抬升和平移,使凹陷中央较厚地层产生隆升,形成中央走滑反转带、伴生的同向走滑断裂和次级同向走滑断裂带;反转带控制了油气的聚集成藏,中央走滑反转带油气分布在馆陶组和明华镇组,主要为重质原油;同向走滑断裂和次级同向走滑断裂带油气分布在东营组,主要为中—轻质原油。     

酒西盆地老君庙逆冲断裂带及其演化

这是一条典型的逆冲断裂带,由老君庙和庙北两逆冲断层组成。断面上陡下缓,向下顺上石炭统太原组软弱层滑脱。该构造带沿走向从东至西位移量和缩短量逐渐减少,褶皱幅度减小但宽度增大,逆冲岩席厚度由薄增厚。岩席厚度的变化可能是导致其它变形差异的主要原因。断裂带的演化过程可分为四个阶段。褶皱尤其是断裂是从东向西、由南向北逐渐发育的。     

黄骅坳陷孔西潜山推覆构造的发现及意义

印支－燕山期的推覆构造在华北地台的北缘、南缘及内部台褶带都已有发现,但在地台东部广大的盆地地区,至今未见有报道。本文通过地震剖面解释、钻孔资料等研究,厘定了黄骅坳陷孔西潜山推覆构造,并分析认为郯庐断裂带的左行剪切运动为其发生、发展的动因模式。这一发现对指导黄骅坳陷及临近盆地基底中进一步的油气勘探具有重要的理论和实践意义。      

库车褶皱冲断带断裂、构造对油气藏的控制作用

充分认识库车褶皱冲断带断裂、构造在油气成藏过程中的作用，将有助于该区和中国西部相似地区的油气预测和勘探。依据断裂的力学性质，分类探讨了该区的断裂及其伴生构造对油气藏的控制作用。在强烈活动时期，断裂均具有疏导功能；在相对稳定时期，断裂的控藏作用随断裂力学性质变化。挤压型断裂以封闭作用为主，相关的圈闭构造有逆断层下盘背斜、逆断层上盘伴生背斜和滑脱层下盘风化壳等；走滑型断裂以垂向疏导和侧向阻隔的双重作用为主，相关的圈闭构造有花状构造和雁列背斜，其中最利于油气聚集的位置是雁列背斜远离断裂的一端和弧形断裂内侧；伸展型断裂以疏导作用和改善储集性能为主，相关的正牵引背斜和反向抬斜断块是钻探成功率最高（接近100%）的圈闭构造。库车褶皱冲断带“封存箱”的实质是断裂构造封存，挤压型和走滑型断裂作为封存箱的顶底板和侧板。     

鄂尔多斯盆地西部逆冲推覆构造带重力资料数字处理及其应用

本文用拉普拉斯方程的级数解形式,对研究区的重力资料作了解析延拓处理,进而阐明逆冲推覆带滑脱面的性质、空间展布及深层构造特征。     

准南前陆冲断带构造特征及其对油气成藏的影响

自晚古生代以来,准噶尔盆地先后经历了海西、印支、燕山和喜马拉雅多期构造运动,伸展、挤压、剪切等构造作用交替进行,多旋回构造发展造成多期活动、类型多样的构造组合,形成了众多不同级次的断裂,发育了许多不同类型的褶皱构造,特别是准噶尔盆地南缘,受天山造山带及邻区构造演化控制,多期不同类型盆地和构造变形叠加,使得准南前陆冲断带断裂发育、构造复杂。指出受新近系以来的强烈冲断构造变形作用,准南前陆冲断带具有自南向北扩展的复杂多变的新生代逆冲挤压构造和埋藏式的冲断楔前缘,发育台阶状逆断层及各类断层相关褶皱,具有“东西分段、南北分排”的特征;造山带隆升时产生的力源在释放过程中克服的阻挡对象不同,导致冲断带东段、中段、西段不同的构造具有相似的构造变形特征的同时又表现出一定的差异。     

塔北隆起轮东斜坡带走滑断层特征及其石油地质意义

走滑断层是轮东斜坡带最主要的断裂构造类型.在新三维地震资料解释的基础上,研究分析该区走滑断层特征、成因及演化,进而探讨其石油地质意义.结果表明:该区断层切面上走滑断层具有形迹丰富、共轭、雁列构造的特征;剖面上走滑断层具有断面陡直、花状构造特点,并具有典型的“海豚效应”和“丝带效应”;受区域剪切作用形成的挤压应力场影响,区内走滑断层形成于海西中晚期,并长期继承性活动;该走滑断层对区内石油运聚保及其再分布具有极其重要的影响,控制了轮东斜坡带寒武—奥陶系的构造样式,改善寒武—奥陶系碳酸盐岩地层的储层储集性能,提高岩溶发育程度,进而影响区内油气成藏和油气分布特征.     

库车再生前陆逆冲带生长褶皱的倾斜剪切恢复

去褶皱倾斜剪切恢复是褶皱作用的逆过程.利用生长地层可以恢复褶皱不同生长阶段的几何形态,建立一系列的不同时期褶皱的几何形态.分析褶皱翼长、褶皱翼倾角、轴面倾角的变化,可以得出褶皱生长机制,同时也用于判断对于地表地质、钻井资料以及地震剖面的解释是否正确.生长褶皱恢复过程中必须遵循地质平衡的准则,同时每一步恢复后的剖面在地质上应该是合理的.用倾斜剪切恢复技术对库车再生前陆逆冲带的生长褶皱进行了系统的恢复.恢复结果表明,米斯布拉克背斜是通过翼旋转发育的,发育过程中背斜顶部逐步少量地进入前翼;依奇克里克背斜是通过膝折带迁移的机制发育的,发育过程中翼倾角不变,翼长逐渐增加;大宛其背斜是通过翼旋转的机制生长的,生长过程中翼长几乎没有发生变化,前翼与向斜的水平地层之间的夹角逐渐减小.这说明库车再生前陆逆冲带是通过翼旋转和膝折带迁移两种机制变形的.褶皱的生长时间、生长机制与烃类的聚集有紧密的关系.