Characteristics and evolution of strike-slip tectonics of the Liaohe Western Sag,Bohai Bay Basin

Because of its rich oil and gas resources and the special tectonic location of the Liaohe Western Sag （the Tanlu Fault traverses the sag）, Bohai Bay Basin, a detailed study of its strike-slip tectonics is significant in revealing the sag＇s tectonic evolution, its control on hydrocarbon accumulation, and the activity history of the northern section of the Tanlu Fault in the Cenozoic. Through systematic structure analysis of 3D seismic data of the Liaohe Western Sag, combined with balanced section analysis, a variety of structural features in relation to right-lateral strike-slip faults, such as echelon normal faults, ＂comb＂ structure, ＂flower＂ structure,＂interpretable＂ and ＂buried＂ strike-slip faults have been revealed exist in the Liaohe Western Sag. According to the research in this paper, the complex structural phenomena in the Liaohe Western Sag could be reasonably interpreted as right-lateral strike-slip activity and the strike-slip activities of the Liaohe Western Sag began in the early Oligocene. The activity was weak at the beginning （E3s1-2）, then strengthened gradually and reached its strongest level in the late Oligocene （E3d1）. In the Miocene, the strike-slip activity was low and then strengthened significantly once again from the Pliocene to the present. It is speculated that the entire northern section of the Tanlu Fault has had a similar evolution history since the Oligocene.

Tectonic evolution and its control over deposition in fault basins: A case study of the Western Sag of the Cenozoic Liaohe Depression, eastern China

The main petroliferous basins in eastern China are Cenozoic fault basins, most of which have experienced two-stage tectonic evolution, i.e., rifting subsidence in the Paleogene and post-rifting thermal subsidence in the Neogene-Quaternary. The episodic tectonic evolution and syndepositional faulting had significant influence on the fault basins in terms of accommodation space, deposition rate, and depositional facies zones. In this study, the tectonic deformation characteristics and the tectonic-depositional evolution of the Western Sag of the Cenozoic Liaohe Depression were investigated by comprehensive analysis of the available geological and geophysical data using the modern theory of tectonic geology and the balanced section technique. The tectonic deformation of the Cenozoic fault basin was characterized by superimposed faults and depression. In addition, there existed relatively independent but still related extensional tectonic systems and strike-slip tectonic systems. The tectonic evolution of the fault basin involved five stages, i.e., initial rifting stage （E2s4）, intense faulting stage （E2s3）, fault-depression transition stage （E3sl2）, differential uplifting stage （E3d）, and depression stage （N-Q）. According to the characteristics of tectonic development and evolution of the Western Sag, the depositional evolution in the Cenozoic fault basin was divided into two stages, i.e., multi-episodic rifting filling in the Paleogene and post-rifting filling in the Neogene-Quaternary. The former rifting stage was further subdivided into four episodes with different characteristics of depositional development. The episodic faulting controlled the filling process and filling pattern of the Cenozoic Western Sag as well as the development and spatial distribution of associated depositional systems, whereas the syndepositional faults that developed in multiple stages in various tectonic positions controlled the development of depositional systems and sand bodies in the Western Sag. That is, the fault terraces on steep slopes controlled the development of sand bodies, the fault terraces on gentle slopes controlled the development of low-stand fan bodies, and the fault terraces or fault troughs in the central basin controlled the development of fluxoturbidite bodies.

Estimation on organic carbon content of source rocks by logging evaluation method as exemplified by those of the 4^(th) and 3^(rd) members of the Shahejie Formation in western sag of the Liaohe Oilfield

One of the most important tasks of evaluating natural resources of petroliferous basins is to determine the organic matter abundance of source rocks in the basin.The usual method for assessing the organic carbon content of source rocks is based on laboratory analyses.There is a deviation in calculating organic carbon content due to the heterogeneous distribution of organic matter and the artificial factors when sampling.According to the continuous characteristics of information logging,the conventional logging curves(mainly acoustics and resistivity,etc.) were calibrated with the organic carbon experimental data of cores,cuttings or sidewall cores.The organic carbon content of source rocks of the 4 th(Es 4) and 3 rd(Es 3) members of the Shahejie Formation in western sag in the Liaohe depression was estimated directly by a great amount of continuous data including resistivity and acoustic logging,etc.Comparison between the results from computer processing and lab analysis of logging data shows that the organic carbon contents derived from the computer processing of logging data have the same reliability and accuracy as the lab analysis results.The present data show that this method is suitable to evaluate the source rocks of western sag in the Liaohe depression and has great potential in evaluating natural resources of sedimentary basins in the future.On the basis of logging data of source rocks,experimental data and existing geochemical analyses of the Liaohe Oilfield,the corresponding total organic carbon(TOC) isograms of source rocks were plotted.The source rocks of Es 4 and Es 3 of the Shahejie Formation are thought to be beneficial to hydrocarbon accumulation due to the high TOC.

Conditions for the Formation of Oil and Gas Pools in Tertiary Volcanics in the Western Part of the Huimin Sag, Shandong and Their Distribution

Conditions for the Formation of oil and gas pools in Tertiary volcanics in the western part of the Huimin sag, Shandong and then (?)stribution have been studied based on the geological, seismic and well-logging information. In this paper, the types and lithofacies of the volcanic rocks in the western part of the Huimin sag are described; the relationship between rocks and electrical properties, the seismic reflection structures, the development and distribution of the volcanic rocks are expounded; and the fourfold role of the volcanic activities in the formation of the oil and gas pools is also dealt with. It is considered by the authors that the volcanic activities were not destructive to the formation of oil and gas pools but a factor favourable to the accumulation of organic matters and their conversion to hydrocarbon. The volcanic rocks might have served as reservoir rocks and cap rocks, or as a synsedimentary anticline. The prerequisites and important factors for the formation of oil and gas pools and their distribution are pointed out in the paper.

准噶尔盆地盆1井西凹陷石炭系火山岩凝析气藏的发现与勘探启示

准噶尔盆地石炭系火山岩油气藏是油气勘探的重点领域之一。根据录测井资料、地球化学分析数据及岩石薄片鉴定资料,结合地球物理方法,厘清了准噶尔盆地盆1井西凹陷石炭系火山岩油气成藏的主控因素,总结出深层火山岩气藏富集规律,明确了有利勘探方向。研究结果表明:(1)准噶尔盆地盆1井西凹陷风城组烃源岩厚度为100~300 m,面积约为5 400 km2,整体进入生凝析油—干气阶段,生气强度大于20×108m3/km2,为凹陷提供了丰富的天然气源。(2)研究区石炭系火山岩岩性复杂,爆发作用形成的安山质火山角砾岩受到风化淋滤作用,可形成物性较好的风化壳型储层。石炭系—二叠系大型不整合面和广泛发育的深大断裂是重要的输导体系,二叠系上乌尔禾组泥岩作为区域盖层,为凝析气成藏提供了保存条件,油藏主要分布在高部位,气藏分布于低部位。(3)通过“两宽一高”(宽方位、宽频带、高密度)技术,提高地震成像精度,联合时-频电磁技术(TFEM),实现了石炭系火山岩的精细刻画,为深层油气藏的勘探提供了有力支撑。石西16井的重大突破,证实了盆1井西凹陷石炭系火山岩具有巨大的勘探潜力。

塔里木盆地西北缘乌什西次凹的地层系统和构造特征

乌什西次凹位于塔里木盆地西北缘,隶属于库车坳陷的乌什凹陷。它位于南天山主山脉(哈尔克山)和塔里木盆地柯坪—温宿凸起之间。区域构造格局上,这里是塔里木克拉通向西北自然延伸的部分。次凹北缘的阿合奇断裂是南天山造山带和塔里木克拉通的分界。乌什西次凹内发育与柯坪—温宿凸起相似的晚前寒武纪—古生代地层系统,包括寒武系、奥陶系和石炭系的烃源岩。新近系—第四系碎屑岩建造直接不整合于变形的古生代被动大陆边缘碎屑岩—碳酸盐岩沉积建造之上;剖面上,向南天山方向加厚,向塔里木克拉通方向减薄,呈现典型的前陆盆地剖面结构特征。这是一个晚新生代陆内前陆盆地,叠加在晚海西期—燕山期古隆起之上。这里的构造变形主要有3期,分别是中海西期、晚海西期—印支期和晚喜山期。变形以厚皮冲断构造及其相关褶皱为主,薄皮构造不发育。平面上,主构造线走向NE-SW。剖面上,以南天山向塔里木冲断为主。

西湖凹陷西次凹古近系花港组—平湖组深层油气成藏过程

西湖凹陷西次凹古近系花港组和平湖组深层油气资源丰富,是东海陆架盆地勘探开发新领域,受储层差异致密化影响,油气成藏机理复杂。为了厘清西次凹深层油气成藏过程,本文通过流体包裹体岩相学特征、显微测温、激光拉曼光谱、包裹体所含油气地球化学等实验分析,结合构造演化、地层埋藏史、热史等,开展了系统的储层特征、油气成藏期次、成藏过程研究。结果表明,花港组深层(>4000 m)和平湖组储层均已致密化,溶蚀孔隙是主要的储集孔隙类型;花港组和平湖组均发育两期油气包裹体,早期含油包裹体较多,晚期以天然气包裹体为主,成藏时间分别为龙井运动期和冲绳运动期,以晚期天然气成藏最为关键。包裹体中油气地球化学特征类似,反映生烃母质以高等植物生源为主,低等生物为辅,与平湖组煤系烃源岩特征一致。冲绳运动叠加平湖组生气增压是晚期天然气成藏的主要动力,此时H10段及以上储层未致密化。根据储层致密化与成藏时序匹配关系可将西次凹M构造深层油气藏类型划分为常规型、先成藏后致密型、先致密后成藏型和边成藏边致密型4种。本文成果可为研究区下一步致密砂岩气的勘探开发部署提供重要的理论依据。

Further Recognition of Petroleum Exploration Potential of Marine Carbonates in Western Tarim Basin

A series of significant discoveries in marine carbonate rocks show great petroleum exploration potential in the Tarim Basin. However, the oil and gas fields discovered in the carbonate rocks are mainly distributed around the Manjiaer Sag in the eastern Tarim Basin. Some explorations occurred and no oil or gas field was discovered around the Awati Sag in the western Tarim Basin. Information from wells and outcrops reveals that there are excellent oil and gas source rock conditions around the Awati Sag. Transformed reef-shoal reservoirs could be formed in the Ordovician carbonate rocks with paleo-geographic background and hydrothermal conditions. Therefore, it is necessary to make a systematical study and overall evaluation of the potential of the periphery of the Awati Sag in terms of source rock evolution, resource potential, high-grade reservoir formation and distribution, and main factors controlling hydrocarbon migration and accumulation.

辽河断陷盆地地层划分对比标志研究

辽河断陷地质构造十分复杂,造成了古近系分割性强、厚度和岩性纵横向变化大等特点.寻找识别标志层,进行精细地层划分对比一直是本区地层研究的难点,制约了油气勘探开发部署.从盆地构造沉积演化分析入手,通过多重地层划分对比方法,对西部凹陷近千口探井进行系统研究,识别了古近系7个区域标志层,描述了古近系沙河街组共14种不同类型底界的接触关系和岩电特征,并以各种类型底界的代表井为基准,划分出同一地层单元内不同类型底界的分布区,使陆相断陷盆地地层划分对比更加简单、具体、易操作,为油气精细勘探提供基础支撑.

准噶尔盆地盆1井西凹陷石炭系—二叠系天然气特征及成藏主控因素

综合利用地震、钻井、测井、岩心、薄片、有机地球化学等资料,对准噶尔盆地盆1井西凹陷石炭系—二叠系天然气的地球化学特征、成因、来源、成藏主控因素以及勘探潜力进行了探讨。研究结果表明:①盆1井西凹陷深层石炭系—二叠系天然气中甲烷的体积分数为70.93%~96.55%,平均值为81.78%,总体为湿气。碳同位素分布相对较广,甲烷碳同位素值为−41.62‰~−30.42‰,平均值为-34.75‰,天然气大多处于成熟—高成熟演化阶段;乙烷碳同位素值为−31.69‰~−24.16‰,平均值为−27.50‰,可见天然气成因以煤型气为主,其次为混合成因气。C7轻烃化合物中甲基环己烷和正庚烷的相对含量均较高,甲基环己烷相对质量分数为32.14%~58.37%,平均值为38.84%,正庚烷相对质量分数为25.37%~56.56%,平均值为47.79%。②研究区天然气成因类型及来源复杂,主要来自于二叠系下乌尔禾组烃源岩的煤型气及其与风城组油型气的混合气,来自风城组烃源岩的油型气较少。③研究区二叠系风城组和下乌尔禾组烃源岩生气潜力大,多种岩性储层发育,断裂和不整合面渗透性砂体为深层天然气的运移成藏提供了输导体系,且石炭系的古凸起和二叠系的岩性圈闭形成互补之势,对天然气在斜坡区的聚集起到了良好的侧向遮挡作用。④研究区鼻凸构造带石炭系火山岩和洼槽二叠系风城组碎屑岩2类规模较大的勘探领域是下一步盆1井西凹陷深层天然气勘探的潜力区。

布尔津盆地西部凹陷乌伦古河组后生氧化作用及成矿潜力分析

布尔津盆地西部凹陷后生氧化作用类型分为潜水氧化和层间氧化。潜水氧化带是由地下水自上而下产生垂直地化分带而形成的,主要分布在乌伦古河组的顶部剥蚀面上有古潜水氧化带发现。层间氧化带是层间承压水侧向迁移而产生的地化分带,鉴于工作重点是寻找与层间氧化带有关的地浸砂岩型铀矿,本文仅对乌伦古河组沉积特征、层间氧化带的特征、铀的迁移和富集做一描述,分析区内铀成矿潜力,为下一步攻深找盲提供了依据。

准噶尔盆地玛湖凹陷西斜坡原油油源解析:基于单体烃碳同位素组成、分子比值与浓度定量分析

通过对玛湖凹陷中部(西斜坡)24个原油样品饱和烃组分、芳烃组分、二苯并噻吩(DBT)、甲基二苯并噻吩(MDBTs)、二苯并呋喃(DBF)和甲基二苯并呋喃(MDBFs)等化合物定量分析及正构烷烃单体C同位素组成分析,将油样分为Ⅰ、Ⅱ两类。与Ⅱ类原油相比,Ⅰ类原油具有:①相对较高的Pr/n-C17、Ph/n-C18值和较低的Pr/Ph值;②相对较高的伽马蜡烷/(C30藿烷+伽马蜡烷)值;③相对较高的C29甾烷异构化比值、三环萜烷/(三环萜烷+C30藿烷)值、三芳甾烷TA(Ⅰ)/(TA(Ⅰ)+TA(Ⅱ)值和甲基二苯并噻吩比值4-MDBT/1-MDBT;④相对较高的二苯并噻吩(DBT)和甲基二苯并噻吩(MDBTs)含量、较低的二苯并呋喃(DBF)和甲基二苯并呋喃(MDBFs)含量和较高的DBT/(DBT+DBF)和MDBTs/(MDBTs+MDBFs)值。其中,两类原油MDBFs含量和DBT/(DBT+DBF)、MDBTs/(MDBTs+MDBFs)值差异比较显著。此外,Ⅱ类原油正构烷烃单体C同位素分布型式具有一定程度的“倒转”,即随碳数增加δ^(13)C值先变轻,至n-C25达到最低值,之后变重,而Ⅰ类原油不具有“倒转”特征。Ⅰ类原油来源于下二叠统风城组烃源岩,Ⅱ类原油来源于中二叠统下乌尔禾组烃源岩与下二叠统风城组烃源岩的原油组分混合产物。Ⅰ类原油比Ⅱ类原油分布于相对较深的储层,两类原油具有不同的运聚通道和分布规律。

辽河西部凹陷新生代断裂构造特征与油气成藏

为了揭示辽河坳陷西部凹陷新生代断裂构造与油气关系,运用油区构造解析理论对西部凹陷新生代断裂构造发育及演化特征进行系统分析。结果表明:以沙三段中下部大套泥岩为界,西部凹陷形成了上下叠加的2个断裂系统,主要发育长寿型、早衰型和后生型3种类型断层和张性正断层、走滑断层、走滑正断层和走滑逆断层4类不同性质断层。断裂活动控制了西部凹陷烃源岩的分布与演化、油气的运聚以及圈闭形成:断陷期是主要的烃源岩形成期,持续沉降有利于烃源岩演化;伸展变形阶段形成的下部断裂系统有利于油气的聚集,走滑变形阶段发育的上部断裂系统有利于油气的运移;构造活动强烈期是圈闭主要形成期,在沙四段—沙三段沉积早期及东营组沉积晚期形成两期主体圈闭。根据断裂发育特征和演化过程,指出双西隐伏走滑断层带和台安—大洼断层带的海外河以南部分是有利勘探区。

烃源岩有机质丰度的测井计算方法及影响因素探讨

近年来,结合丰富的地球物理信息和地球化学实验数据来研究烃源岩,可有效克服常规岩样分析资料连续性差、成本高的难题,且获得了广泛的应用,但在实际应用过程中发现,其准确性并非很高。文中以辽河西部凹陷为例,结合取心井SG1的烃源岩地球化学和测井资料,重点对比了不同成熟度范围的烃源岩的测井响应差异。通过讨论影响烃源岩TOC测井计算方法准确性的各种因素,对比了最小二乘法与ΔlgR方法的优缺点,认为最小二乘法拟合公式的3个常数(A,B,C)包含了多种影响计算结果的因素,因此,最小二乘法更能反映烃源岩层TOC的变化,且在应用时具有较强的可操作性。

烃源岩生烃潜力恢复与排烃特征分析——以辽河西部凹陷古近系烃源岩为例

根据排烃门限理论,对生烃潜力法进行了改进,建立了生烃潜力指数恢复模型,并对辽河西部凹陷各类型有机质的排烃特征分别进行了详细分析。研究表明,研究区不同类型有机质烃源岩排烃特征存在很大差异,有机质类型越好,排烃门限深度越浅,Ⅰ型和ⅡA型有机质的排烃门限深度为2 200 m,ⅡB型为2 700 m,Ⅲ型为2 900 m;相同埋深条件下,有机质类型越好,烃源岩单位有机碳排烃量越大,达到排烃高峰期越早,排烃效率也越高。研究区排烃期主要有2期,第一期为东营组沉积期(主要为东营组抬升遭受剥蚀前);第二期为明化镇组沉积期至现今。研究区烃源岩总排烃量为156.23×108t,其中沙三段和沙四段烃源岩分别占61.5%和21.2%,是西部凹陷的主力排烃源岩。

异常低压背景下储集层成岩特征——以渤海湾盆地辽河坳陷西部凹陷南段古近系为例

应用大量压力、物性、试油测试数据,分析渤海湾盆地辽河坳陷西部凹陷南段古近系低压和异常低压对储集层成岩作用和物性的影响。当地层压力为低压或异常低压时,孔隙流体压力较小,上覆静岩压力主要由砂岩骨架颗粒承担,有时甚至出现"过压实"现象,导致储集层致密,促进机械压实作用;地层剩余压力与碳酸盐胶结物含量之间呈负相关关系,具有低压或异常低压的致密砂岩碳酸盐胶结物含量比处于静水压力—弱超压条件下的砂岩更高;低压区和异常低压区的砂体孔隙流体中含有较多的Si4+,有利于硅质胶结作用的进行;处于低压或异常低压背景下的储集层,当溶蚀作用发生时,其原始物性已经相对较差,不利于溶蚀流体的注入和溶解物质的排出,溶蚀作用相对较弱。因此,发育低压或异常低压的储集层物性较差。

兴隆台地区沙三段砂体发育模式与岩性油气藏勘探

兴隆台地区位于辽河坳陷西部凹陷。沙三段沉积时期,西部凹陷正处于凹陷的强烈断陷期,深水浊流沉积十分发育。当时,处于西部凹陷深陷带的兴隆台地区存在一个水下低凸起,阻止了来自研究区东部的近物源沉积物,浊流携带物被迫倾泄在水下凸起的东坡和深洼中。因此,兴隆台潜山的东斜坡及其向东延伸的深洼区发育上倾尖灭型和透镜状浊流砂体。这些浊流砂体纵向主要分布于层序界面附近的湖侵体系域下部和湖退体系域上部,最大湖泛面附近也有分布。砂体分布与层序界面的这种关系,反映断陷盆地断裂活动是导致湖水升降和发生浊流沉积的主要控制因素。砂体这种分布模式对预测岩性油气藏分布有指导意义。

辽河断陷西部凹陷沙三段沉积相及相模式

西部凹陷沙河街组三段沉积厚度大,分布范围广,是深层储层的重要组成部分。通过对沙三段岩芯、钻/测井和地震资料的研究,识别出冲积扇、扇三角洲、近岸浊积扇、远岸浊积扇、断槽重力流水道、滑塌浊积扇及湖泊等7种沉积相类型,其中扇三角洲和浊积扇中各砂体微相的相互重叠构成区内最好的储层;该区沙三段沉积时期主要发育5套沉积体系,以冲积扇-扇三角洲-湖底扇沉积体系为主;在沙三段早中期,湖盆为水进沉积序列,西斜坡发育的扇三角洲和远岸浊积扇的砂体逐渐东移,展布范围逐渐扩大,而东陡坡扇三角洲中各亚相相带逐渐变窄,近岸浊积扇砂体呈长条状展布;到沙三段晚期,湖盆为水退沉积序列,西斜坡砂体展布范围、砂体厚度基本继承了前期的特征,东陡坡扇三角洲内各亚相相带逐渐变宽,并且向湖盆凹陷中心推进;沉积相带展布与迁移特征反映了古地形、边界同生断层、湖平面的相对变化以及物源的供给量等因素对沉积格局的控制。

辽河坳陷双台子构造带沙三段沉积相展布特征与沉积主控因素

辽河西部凹陷双台子构造带E2s3发育重力流沉积,沉积相类型为湖底扇中扇和外扇,同沉积断层和古地貌是控制沉积的主要因素。论文描述了同沉积断层和古地貌的展布特征,并以此为基础,开展了沉积相主控因素的研究工作。建立了"沟道控砂,坡度控形,物源控供给"的沉积模式:辫状沟道沉积分布在受同沉积断层和古地貌的联合控制的古沟道内。古地貌坡度小,辫状沟道沉积向盆地中心搬运的距离长,沟道弯曲度大,沉积分异作用更加明显,盆地内主要以砂岩与泥岩互层为特征(双南)。古地形坡度大,辫状沟道沉积向盆地中心搬运距离短,沟道弯曲度小,沉积分异作用差,盆地内主要以厚层砂岩和薄层泥岩组合为特征(双台子)。双台子和双南具有不同的物源,两个地区在同一层序内具有不同的砂体叠置样式。双南和双台子沉积作用机制上的不同,导致了二者在沉积相带展布、砂体叠置样式等方面的差异。对储集体而言,双台子比双南具有更有利的沉积相带。

渤海湾盆地辽河西部凹陷古近纪变形特征及成因

辽河西部凹陷位于渤海湾盆地东北部,其古近纪构造演化与成因机制研究不仅对油气勘探具有指导作用,同时对深入分析渤海湾盆地和郯庐断裂带的成因演化也具有启示意义。通过三维地震资料系统解释和编图、同沉积断裂系统与沉积厚度关系分析、断层活动强度统计等方面研究,认为辽河西部凹陷在古近纪经历了早期伸展和晚期走滑两期变形叠加过程。早期伸展变形发生在始新世,包括初始断陷期(Es4)和强烈断陷期(Es3)两个阶段,形成北东向主干断层及东断西超的半地堑世组合,控制北东向沉积中心的展布;晚期走滑变形发生在渐新世东营期,使先存北东走向基底断层发生右旋走滑位移,并诱导盖层形成近东西向新生正断层组合,从而形成南部张扭沉降、北部压扭隆升的构造格局。Es1-2期是从伸展变形向走滑变形发展的过渡时期,构造活动微弱。区域构造应力场分析和沙箱实验证明,始新世北东向伸展断裂系统受太平洋板块俯冲产生的北西-南东向弧后拉张作用控制,而渐新世走滑断裂系统则受郯庐断裂右旋走滑作用控制,动因来源于印度-澳大利亚板块向欧亚板块俯冲作用产生的远程效应。