Types,characteristics and implication for hydrocarbon exploration of the Middle Miocene deep-water sediments in Beikang Basin,southern South China Sea

The internal seismic architectures of the Middle Miocene in Beikang Basin, southern South China Sea, were investigated and described using regional 2D seismic data from Guangzhou Marine Geology Survey. In particular, five typical seismic facies were identified based on an integrated analysis of the amplitude, continuity, contact relationship, and morphologies of seismic reflections. Bathyal-abyssal fine-grained sediments, deltaic front sandy bodies, turbidites, and small-scale turbidite channels were developed in the Middle Miocene according to the tectonic-sedimentary evolution of the sedimentary basins in the southern South China Sea. The findings of this study suggest that deltaic front sandy bodies and turbidites can be considered as the two major types of deep-water clastic reservoirs for the depression stage of Beikang Basin. A well-developed source-reservoir-cap assemblage was composed by deep rift-stage source rocks, deep-water clastic reservoirs of the Middle Miocene, and bathyal-abyssal deep-water fine-grained sediments after the Middle Miocene, implying a good potential for hydrocarbon exploration.

Paleocene deep-water sediments and radiolarian faunas: Implications for evolution of Yarlung-Zangbo foreland basin, southern Tibet

This is the first report on the Paleocene deep-water sequences and radiolarian faunas, which are distributed along the southern side of the Yarlung-Zangbo suture zone. The Zheba group is coined to indicate these Paleocene sequences which are subsequently divided into two lithostratigraphic units based on the lithology observed in the field. The lower unit characterized by the rhythmic cherts and siliceous shales is named the Sangdanlin formation, and the upper one composed mainly of flysches is termed the Zheya formation. The radiolarian faunas from the Zheba group are assigned to the RP1-RP6 zones of the Paleocene age. The Early Paleocene ra- diolarian assemblages have the potential to be established into the low latitude radiolarian zones and to fill in the gap between the Late Cretaceous and the Late Paleocene radiolarian zonations. The radiolarian dating provides a valuable tool for the regional correlation and reconstruction of the sedimentary environment of the Neo-Tethyan Ocean. The preliminary work shows that the Paleo- cene sequences accumulated in a foreland basin resulted from the southern Asian margin loading onto the northern Indian passive continental margin. The Yarlung-Zangbo foreland basin se- quences deposited on the Indian passive continental margin also resulted in many good source- reservoir-covering assemblages for oil and gas resources.

ICHNOFACIES IN LATE PALEOZOIC DEEP-WATER SLOPE SEDIMENT OF JUNGGAR BASIN AND ITS ENVIRONMENTAL ANALYSIS

This paper mainly discusses 15 kinds of ichnogenus found for the first time in the study area from the water depth distribution, body size of trace fossils and the relationship between sedimentary environment and deep-water ichnofacies, based on the summarizing of the sedimentary character of deep-water slope environment in the study area. According to the relationship between the type of turbidite and the combination of trace fossils, 15 kinds of ichnogenus are divided into two types, transition type Zoophycos ichnofacies and deep-water type Nereites ichnofacies. The former is mainly distributed in the transitional area between proximal to distal area of turbidite and the latter in the distal area.

鄂尔多斯盆地超低渗透储层成因研究及意义

鄂尔多斯盆地超低渗透油藏资源丰富,但由于其储层物性差,非均质性强,导致开发难度加大。通过对沉积微相与成岩相的综合研究认为:在超低渗透储层背景下存在相对高孔、高渗区,三角洲前缘水下分流河道微相与辫状浊积水道微相碎屑分选较好,杂基含量较低,成岩早期压实胶结作用相对较弱,孔隙保存较好;成岩后期地下流体运动较活跃,溶蚀、溶解作用加强,为相对有利的储集相带。深入研究超低渗透储层的成因,对优选油气相对富集区,促进超低渗透油藏的有效开发提供了理论依据。

车排子地区侏罗系沉积模式及有利区带分析

车排子地区是准噶尔盆地重要的油气富集区,由于其处于盆缘超剥带,对侏罗系地层归属及展布特征认识尚不清楚。为了弄清该区侏罗系地层对砂体成因类型及有利储层分布的影响,在地层精细划分的基础上,结合剥蚀量计算,对侏罗系沉积期古地貌进行了恢复;结合残留地层的沉积相标志分析,建立了侏罗系沉积模式,还原了该时期的岩相古地理;通过储层物性研究,明确了有利储层的沉积相类型,结合岩相古地理分布,预测了研究区有利储层的展布。结果表明:车排子地区侏罗系发育扇三角洲相和辫状河三角洲相,车排子凸起东翼陡坡带发育受限型扇三角洲,四棵树凹陷南部陡坡带发育扇三角洲,四棵树凹陷北部缓坡带发育辫状河三角洲。辫状河三角洲前缘砂体为有效储层,是下一步重点勘探目标。

松辽盆地北部四方台组—明水组高精度层序地层特征与有利区带预测

应用沉积学和层序地层学的原理和方法,利用地震、测(录)井、岩芯、露头、古气候及古生物等资料,通过地震合成记录标定,结合盆地区域构造演化特征分析,在松辽盆地北部四方台组—明水组共识别出区域不整合面、古暴露界面、河道侵蚀冲刷面、地层叠加型式转换面4类层序界面,并识别划分出1个新的超层序界面SB4,最终将四方台组—明水组划分为1个超层序组,2个超层序(SSQ1和SSQ2),6个三级层序(SQ1-SQ6),17个体系域,建立高精度层序地层格架。盆地北部层序地层格架内沉积充填演化规律为:层序SQ1～SQ3(SSQ1)沉积时期,盆地主要发育南北向长轴物源的河流及滨浅湖沉积;层序SQ4～SQ6(SSQ2)沉积时期,盆地主要发育东西向短轴物源的辫状河三角洲及滨浅湖沉积;从四方台组时期开始,盆地沉积中心向西北方向不断迁移。根据层序地层格架内的储盖组合分布及成藏条件综合分析可知:纵向上四方台组时期层序SQ1发育本区最有利的储盖组合,而大安—新站地区SQ1低位体系域厚层河床砂岩为本区最有利的油气聚集区带,最有可能形成构造-岩性次生油气藏。

东濮凹陷沙三段隐蔽油气藏分布规律研究

通过高精度层序地层学的研究,认为东濮凹陷是一个多物源、近物源、具有多个沉积沉降中心的内陆盐湖盆地。其分布规律以围绕主要生油洼陷周边分布为特色,形成了三大有利富集区带:东部洼陷带(环濮城-前梨园洼陷)、西部洼陷带(环柳屯-海通集洼陷)和濮卫环洼带(环濮城-卫城次洼带)。近几年的勘探实践证实了这一认识。

基于Flow-3D的水平射流冲刷泥沙数值模拟

为了模拟分析闸口水平射流对下游泥沙冲刷的全过程,基于水工模型试验,采用Flow-3D软件中的泥沙冲刷模型结合RNG模型和FAVOR方法,进行了水平射流冲刷固定底板下游泥沙的模拟试验。根据原水工模型条件,结合模型试验结果,对冲刷过程中的水面线、流速分布、冲坑深度和堆丘高度进行了对比分析。结果显示,数值模拟与原试验结果中水面线和流速分布吻合度很高,冲刷过程中的冲坑深度与堆丘的高度也很接近。分析了冲刷过程中的泥沙运动,模拟了不同粒径泥沙的冲刷过程并将结果进行对比,发现达到冲刷平衡阶段时冲坑深度与堆丘高度随泥沙粒径的增大而减小,该结论符合理论分析,证明该软件中泥沙模型可用于物理试验中的有关变量分析。

滨里海盆地盐下层系的油气地质特征

对滨里海盆地盐下层系的地层与沉积以及石油地质等特征进行了综合研究 ,抓住了盐下层系储集体发育与分布这一油气成藏的关键 ,并通过对已发现的油气田 (藏 )的特点和分布规律分析 ,认为在盐下层系中 ,卡腊通—田吉兹隆起区和北里海—阿兹吉尔隆起区为有利勘探目标区 ;盆地东部延别克—扎尔卡梅斯和扎纳若尔地区为较为有利勘探目标区 ;盆地西部和西南部的阿斯特拉罕—阿克纠宾斯克隆起带的西南坡和西坡以及盆地西北部的乌津地区为具有一定勘探潜力目标区。

海域天然气水合物钻探研究进展及启示(I):站位选择

本文通过对国外海域天然气水合物钻探的调研，选取布莱克海台、水合物脊、墨西哥湾、日本南海海槽、韩国郁龙盆地、印度大陆边缘等区域，从水合物站位选择目的和站位选择依据这两个方面进行归纳总结和系统对比。研究指出，根据水合物的实际产出和赋存，可将其划分为两大类型：赋存于海底浅表层的水合物（一般在海底之下100m范围内）和赋存于海底之下中一深层的水合物（一般在海底之下100～400m范围内）。前者的主要识别依据为海水异常、含气流体运移通道和异常地形地貌特征，而后者的主要识别依据为地球物理异常反射特征、含气流体运移通道和有利沉积体。因此，如果将水合物的形成、聚集和分布比喻为一个有机的整体，那么“运”和“聚”就构成了这个系统的“骨骼”和“血液”，它们将控制远景区内的水合物分布。将“水合物识别标志”、“有利沉积体展布”和“流体运移通道”三者有机地结合在一起，可以达到更准确地预测和描述水合物矿体的目的，这是今后海域水合物钻探站位选择依据的主要发展方向。

黄河小浪底水库拦沙后期运用方式探讨

简要分析了小浪底水库拦沙后期"多年调节泥沙,相机排沙出库"运用的必要性,初步拟定了水库调节指令,结合水库及下游河道淤积发展过程预测,探讨了拟定运用方式的合理性。

低渗透油藏网状河道岔道口优质储层特征及其控制因素

松辽盆地南部大情字井地区葡萄花油层多为中低孔、低渗透、薄层砂岩储层,其外围砂体储层特征、优质储层展布规律以及储层质量控制因素不明确,储层特征变化是制约勘探开发的重要因素。利用岩心、铸体薄片、常规压汞分析化验等资料对储层特征研究表明,网状河道岔道口砂体是优质储层发育的新领域,储层岩石类型主要为岩屑长石砂岩,储集空间类型以次生溶蚀孔隙和残余原生孔隙为主;孔隙结构发育良好,主要为中低孔中喉型;试油产液量高。对于网状河道岔道口优质储层的形成,沉积作用是基础条件,成岩作用中溶蚀作用是其形成的关键因素。

Migrated hybrid turbidite-contourite channel-lobe complex of the late Eocene Rovuma Basin, East Africa

Analysis of 3 D seismic data and well log data from the Rovuma Basin in East Africa reveals the presence of a late Eocene channel-lobe complex on its slope.The first two channels,denoted as channel-1 and channel-2,are initiated within a topographic low on the slope but come to a premature end when they are blocked by a topographic high in the northwest region of the basin.New channels migrate southeastward from channel-1 to channel-6 due to the region’s sufficient sediment supply and stripping caused by bottom currents.The primary factors controlling the development of the channel complex include its initial paleo-topographic of seafloor,the property of gravity flows,the direction of the bottom current,and the stacking and expansion of its levees.The transition zone from channel to lobe can also be clearly identified from seismic sections by its pond-shaped structure.At a certain point,thest systems record a transiton from erosive features to sedimentary features,and record a transition from a confined environment to an open environment.Channels and lobes can be differentiated by their morphologies:thick slump-debris flows are partly developed under channel sand sheets,whereas these slump-debris flows are not very well developed in lobes.Well log responses also record different characteristics between channels and lobes.The interpreted shale volume throughout the main channel records a box-shaped curve,thereby implying that confined channel complexes record high energy currents and abundant sand supply,whereas the interpreted shale volume throughout the lobe records an upward-fining shape curve,thereby indicating the presence of a reduced-energy current in a relatively open environment.Within the Rovuma Basin of East Africa,the average width of the Rovuma shelf is less than 10 km,the width of the slope is only approximately 40 km,and the slope gradient is 2°–4°.Due to this steep slope gradient,the sand-rich top sheet within the channel also likely contributes to the straight feature of the channel system.It is currently unclear whether the bottom current has any effect on its sinuosity.

Distribution characteristics, exploration and development, geological theories research progress and exploration directions of shale gas in China

The shale gas resources in China have great potential and the geological resources of shale gas is over 100×10^(12)m^(3),which includes about 20×10^(12)m^(3) of recoverable resources.Organic-rich shales can be divided into three types according to their sedimentary environments,namely marine,marine-continental transitional,and continental shales,which are distributed in 13 stratigraphic systems from the Mesoproterozoic to the Cenozoic.The Sichuan Basin and its surrounding areas have the highest geological resources of shale gas,and the commercial development of shale gas has been achieved in the Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation in these areas,with a shale gas production of up to 20×10^(9)m^(3) in 2020.China has seen rapid shale gas exploration and development over the last five years,successively achieving breakthroughs and important findings in many areas and strata.The details are as follows.(1)Large-scale development of middle-shallow shale gas(burial depth:less than 3500 m)has been realized,with the productivity having rapidly increased;(2)breakthroughs have been constantly made in the development of deep shale gas(burial depth:3500-4500 m),and the ultradeep shale gas(burial depth:greater than 4500 m)is under testing;(3)breakthroughs have been made in the development of normal-pressure shale gas,and the assessment of the shale gas in complex tectonic areas is being accelerated;(4)shale gas has been frequently discovered in new areas and new strata,exhibiting a great prospect.Based on the exploration and development practice,three aspects of consensus have been gradually reached on the research progress in the geological theories of shale gas achieved in China.(1)in terms of deep-water fine-grained sediments,organic-rich shales are the base for the formation of shale gas;(2)in terms of high-quality reservoirs,the development of micro-nano organic matter-hosted pores serves as the core of shale gas accumulation;(3)in terms of preservation conditions,weak structural transformation,a moderate degree of thermal evolution,and a high pressure coefficient are the key to shale gas enrichment.As a type of important low-carbon fossil energy,shale gas will play an increasingly important role in achieving the strategic goals of peak carbon dioxide emissions and carbon neutrality.Based on the in-depth study of shale gas geological conditions and current exploration progress,three important directions for shale gas exploration in China in the next five years are put forward.

Discovery of lacustrine shale deposits in the Yanshan Orogenic Belt,China: Implications for hydrocarbon exploration

The mechanism of formation of lacustrine deposits within stable orogenic belts and their potential for shale oil and gas exploration are frontier themes of challenge in the fields of sedimentology and petroleum exploration. Orogenic belts witness strong tectonic activities and normally cannot host stable lacustrine basins and deep shale formations. Therefore, basins in orogenic belts are considered to have no potential to form shale hydrocarbon reservoirs. Here we investigate the Luanping Basin located in the Yanshan orogenic belt where previous studies regarded rivers and fan deltas as the major main Mesozoic deposits. Based on detailed field exploration and scientific drilling, we report the finding of a large number of lacustrine shale continental deep-water deposits in the Mesozoic strata. Our finding of the occurrence of active shale oil and gas also in this basin also subvert the previous perceptions.We report SHRIMP zircon U-Pb age that define the bottom boundary of the target interval as 127.6 ± 1.7 Ma belonging to the early Cretaceous strata. Tectonics and climate are considered to be the main factors that controlled the deep-water sedimentation during this period. The drill cores revealed evidence of shale gas and the TOC of shale is 0.33%–3.60%, with an average value of 1.39% and Ro is 0.84%–1.21%, with an average value of 1.002%. The brittleness index of shale is between 52.7% and 100%. After vertical well fracturing, the daily gas production is more than 1000 m^(3). Our findings show that the basin has considerable potential for shale oil and gas. The geological resources of the shale gas in the Xiguayuan Fm. are estimated as 1110.12 × 10^(8) m^(3), with shale oil geological resources of 3340.152 × 10^(4) t. Our findings indicate that the Yanshan orogenic belt has potential exploration prospect. This work not only redefines the Luanping Basin as a rift deep-water Mesozoic Lake Basin, but also rules out the previous notion that the basin is dominated by shallow water sediments. The discovery of shale oil and gas also provides an important reference for subsequent petroleum exploration and development in this basin. Our study shows that shale oil and gas reservoirs can be found in the lacustrine basins of orogenic belts which were strongly influenced by volcanism. These results have significant implications for the sedimentology and oil exploration in the Qinling and Xingmeng Orogenic Belts of China, as well as those in other terranes of the world including the New England Orogenic Belt in Australia.

云南省新街-董干地区地球化学特征及找矿方向

以云南省新街-董干地区1∶50000水系沉积物测量成果为基础,统计分析了水系沉积物地球化学参数。运用变异系数、成矿有利度、聚类分析及因子分析等方法分析区内19种元素的地球化学特征,划分出五类成矿元素组合,确定了主成矿元素。根据组合异常的空间分布及特征,圈定34处综合异常,结合成矿地质条件划分了四处成矿远景区。

Different initial density turbidite sediments with coarse grain injection and their corresponding flow pattern: Additional insights from numerical simulation in a study case of South China Sea

The work presents the sedimentology and depositional results of the turbidity flow from Miocene to Pliocene along the North Slope of South China Sea(SCS).The integration of the core-log-seismic data has enabled us to clarify turbidity flow with different density and characterize their corresponding seismic geomorphic sedimentation.Based on the differences between the initial density and the later,we classified the turbidity flow into two types,namely:low-and high-density flow with coarse grain injection.According to the hydrodynamic numerical simulation results,we constructed different subcritical turbidity flow models with various density and rebuilt the depositional pattern along the slope.As to the numerical simulation model,we introduced the erosion rate into the classical full Reynolds-averaged N-S(RANS)equation,which is suitable to the deep-sea slope area.Through comparison of the above simulation models,the results show that the high-density turbidites with coarse-grained injection are mostly developed with lower vertical erosion rates and higher lateral abrasion rates.They are characterized with multi-branched and lobe-shaped sedimentary volumes,while low-density turbidites with coarse-grained injection are characterized with higher vertical erosion rates and lower lateral abrasion rates.And this kind of turbidites can generate single-branched and banding deposits.In addition,the fluctuating sea levels and the varying topographies are important to influence the subcritical turbidity flow models in the deep-water slope.

伊洛瓦底盆地始新统沉积相及其油气勘探有利区域

将伊洛瓦底盆地始新统沉积相划分为冲积扇陆相沉积相、浪控三角洲沉积相、河口湾海陆过渡沉积相和无障壁海岸等海相沉积相。在此基础上,了解始新统各地层的沉积相分布情况和整个沉积相演化过程,总结该盆地始新统沉积相的主要沉积模式——浅海陆棚沉积模式和冲积扇—浪控三角洲沉积模式。最后,综合评价该盆地始新统有利勘探区域。

文昌Ⅹ油田物性主控因素定量分析及有利区预测

文昌Ⅹ油田目的层珠海组是低渗背景下发育“甜点”的典型储层,有利区的预测问题亟待解决。为此,针对珠海组分析沉积作用和成岩作用对其物性分布规律的影响。应用成岩数值模拟方法,综合考虑成岩与沉积两大物性影响因素,建立孔隙度预测模型。研究表明:中粗砂岩物性较好,水下分流河道根部物性最好;压实作用和胶结作用降低了储层物性,溶蚀作用改善了储集空间,且压实作用是低渗储层形成的最主要因素。珠海组二段和珠海组三段的孔隙度分布规律存在差异,但总体上有利区分布于靠近南大断裂的区域,埋深相对较浅、成岩强度较弱、离物源较近。

基于测井与录井资料预测W区域马家沟组马五7有利区

针对延长气田的勘探开发现状,马家沟组中组合的探索认知由于岩心资料不足等客观原因,只能通过测井资料及录井资料来判断识别储层,Y802-1井的中下组合试气取得突破,确定了马家沟组中下组合勘探开发的巨大潜力。综合前人认识研究及文献调研,结合区域构造、小层厚度、电性特征及录井气测解释评价,对W区域马五段马五7小层进行储层特征研究,并预测了有利储层发育的平面分布。