Slope structures and formation of rock–soil aggregate landslides in deeply incised valleys

Rock–soil aggregate landslides(RSALs) are a common geological hazard in deeply incised valleys in southwestern China. Large-scale RSALs are widely distributed in the upper reaches of the Dadu River, Danba County, Sichuan Province, and are influenced by slope structure, which can be divided into open, lock, strip, and dumbbell types, as well as soil type and meso-structure, which can be classified as layered rock–soil aggregate, block-soil, and grainsoil. In this study, the evolution of four types of structures, such as layered-dumbbell, block-soil lock, banded block-soil, and block-soil open types, were analyzed by field surveys, surface and deep displacement monitoring, and Flac3 D. It was found that the Danba reach of the Dadu River showed incised valley through the evolution from wide to slow valley affected by internal and external geological processes since the Quaternary Glaciation. In the layered-dumbbell rock–soil aggregate, the main sliding pattern is multi-stage sliding at different depths. Circular sliding in the trailing edge and plane sliding along the bedrock in the front edge body occurin the block-soil-lock type aggregate. Large-scale multi-level and circular sliding over long distances occur in the banded block-soil aggregate. The blocksoil open type is stable, with only circular sliding occurring in local and shallow surfaces of the body. The monitoring and numerical simulation results further show that slope structure and regularity have diversified with RSALs. The results provide a basis for analyzing the stability mechanism of RSALs and preventing RSALs in deeply incised valleys.

Deformation and failure characteristics of anchorage structure of surrounding rock in deep roadway

This paper investigated the stress evolution,displacement field,local deformation and its overall distribution,and failure characteristics of the anchorage structure of surrounding rock with different rockbolt spacing through the model experiments.The influences of the pre-tightening force and spacing of rockbolt on the support strength of the anchorage structure of surrounding rock were analyzed by the simulation using FLAC3D numerical software.The support scheme of the excavated roadway was then designed,and the effectiveness of this support scheme was further verified by the displacement measurement of the roadway.The results showed that the maximum displacement between the roof and floor of the west wing track roadway in Kouzidong coal mine,China is about 42 mm,and the maximum displacement between its both sides is about 72 mm,indicating that the support scheme proposed in this study can ensure the stability and safety of the excavated roadway.

Deep structural research of the South China Sea: Progresses and directions

The South China Sea(SCS)is the hotspot of geological scientific research and nature resource exploration and development due to the potential for enormous hydrocarbon resource development and a complex formation and evolution process.The SCS has experienced complex geological processes including continental lithospheric breakup,seafloor spreading and oceanic crust subduction,which leads debates for decades.However,there are still no clear answers regarding to the following aspects:the crustal and Moho structure,the structure of the continent-ocean transition zone,the formation and evolution process and geodynamic mechanism,and deep processes and their coupling relationships with the petroliferous basins in the SCS.Under the guidance of the“Deep-Earth”science and technology innovation strategy of the Ministry of Natural Resources,deep structural and comprehensive geological research are carried out in the SCS.Geophysical investigations such as long array-large volume deep reflection seismic,gravity,magnetism and ocean bottom seismometer are carried out.The authors proposed that joint gravitymagnetic-seismic inversion should be used to obtain deep crustal information in the SCS and construct high resolution deep structural sections in different regions of the SCS.This paper systematically interpreted the formation and evolution of the SCS and explored the coupling relationship between deep structure and evolution of Mesozoic-Cenozoic basins in the SCS.It is of great significance for promoting the geosystem scientific research and resource exploration of the SCS.

STRUCTURAL EVOLUTION AND METALLOGENY OF SOUTH XINJIANG METALLOGENIC BELT,JIANGXI,SOUTH CHINA

ＳＴＲＵＣＴＵＲＡＬＥＶＯＬＵＴＩＯＮＡＮＤＭＥＴＡＬＬＯＧＥＮＹＯＦＳＯＵＴＨＸＩＮＪＩＡＮＧＭＥＴＡＬＬＯＧＥＮＩＣＢＥＬＴ，ＪＩＡＮＧＸＩ，ＳＯＵＴＨＣＨＩＮＡＬｉｕＪｉｓｈｕｎＷｕＹａｎｚｈｉＬｉＰｅｉｚｈｅｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＧｅ...

Deep Processes of Basin Evolution:A Case Study of the Southern Songliao Basin and Adjacent Area,NE China in Mesozoic-Cenozoic

In south of the Songliao Basin and adjacent area of NE China, there are several high conductive layers in crust and upper mantle. Those layers are interpreted as detachment and rheology, which represent some features of lithosphere, asthenosphere and Moho, and related to the crust-mantle structure of the continent in the study area. The differences of the crust-mantle structures in different places in the study area reflect the differences in the movement and evolution of asthenosphere, lithosphere and crust. The differences can be summarized as follows. (1) Along the south profile of MT, the buried depth of the surface of Moho is 31 ～34 km beneath the Liaohe Basin and 35～37 km beneath the west Liaoning area. Along the north profile of MT, the buried depth of Moho is 32～33 km beneath Changtu area and 36～37 km beneath Kailu area in southern Songliao Basin. The buried depth beneath the central of the Songliao Basin is 29 km.(2) The difference of thickness of lithosphere exists in the south area and the north area of Chifeng-Kaiyuan fault. The thickness of lithosphere is about 65～120 km in the south of the fault, thickening from east to west. The top surface of asthenosphere is highly uplifted in the Liaohe Basin and the highest point is about 65 km in buried depth. The thickness of lithosphere in the north of the fault is about 60～65 km, thinner about 25 km than that in the south of the fault (West Liaoning). Deep processes such as upwelling of mantle thermal flow, extension of lithosphere, underplating, and thinning and subsidence of crust, evidenced from the crust-mantle structures were the direct forces of the basin formation in the study area during the Mesozoic-Cenozoic.

四川盆地及周缘前震旦系裂谷特征与油气地质意义

四川盆地及周缘已被证实发育较大规模的前震旦系裂谷,但其在盆地内部的展布及发育特征尚不明确,因此在一定程度上制约了对盆地深部构造格局的认识。为此,在前人研究的基础上,利用最新的重磁电资料,通过联合解译和小子域滤波等新技术对新元古界构造形态进行了研究,同时结合区域地震大剖面的精细解释并辅以航磁资料进行验证,分析了新元古代裂谷的特征及其对上覆地层的沉积控制作用。研究结果表明:①盆地内部自西北至东南共发育3条近乎平行的前震旦系裂谷,其中以川中裂谷规模最大;②裂谷内部发育一系列与裂谷走向近平行的次级正断层,将裂谷内部结构复杂化,形成一系列断陷;③裂谷内断层在平面上呈平行/斜列式、相向/相背平行式及同向平行式组合,对应在剖面上呈阶梯式、垒堑式、地堑式及铲式半地堑式等组合特征;④盆地东北部盆缘露头揭示南华系—陡山沱组在裂谷内发育冰期—间冰期交互沉积,主要为三角洲、陆棚与斜坡盆地相碎屑岩和冰碛岩。结论认为,应用重磁联合解译+井震资料修订+露头剖面验证的新方法,证实四川盆地前震旦系裂谷的存在,且南华纪裂谷边界(主干)断裂控制了上覆地层沉积古地理格局和坡折带的发育,部分裂谷控制了寒武系或早古生界沉积中心的分布,并对后期沉降中心、构造圈闭的形成以及含油气系统有着极为重要的影响。

深层-超深层致密储层天然裂缝分布特征及发育规律

天然裂缝是深层-超深层致密储层的有效储集空间和主要渗流通道,影响着致密储层油气的运移、富集、单井产能、开发方式及开发效果。通过对近年来致密储层裂缝研究成果总结和文献综述,分析了深层-超深层致密储层天然裂缝分布特征及发育规律。将致密储层天然裂缝分为大尺度裂缝、中尺度裂缝、小尺度裂缝和微尺度裂缝4个级别。不同尺度裂缝分布具有幂律分布的特点,裂缝尺度越大,数量越少;裂缝尺度越小,数量越多。大、中尺度裂缝主要起渗流作用,小尺度裂缝主要起渗流和储集作用,而微尺度裂缝主要起储集作用。在地层埋藏过程中的应力体制演化决定了不同时期天然裂缝的类型、产状及其力学性质;构造应力大小、岩石力学层的力学性质和厚度差异控制了多尺度裂缝的形成分布及其发育程度。构造变形导致不同构造部位的局部应力和应变分布产生差异,增强了裂缝发育的非均质性。逆冲断层通过控制其上盘地层变形控制了“裂缝域”的分布规律;走滑断层的组合样式、活动方式和岩石力学层共同控制了相关裂缝的三维空间展布。裂缝形成演化过程中的开启-闭合规律决定了裂缝的储集空间,记录了裂缝有效性的演化历史。

南海北部被动陆缘洋陆转换带张裂–破裂研究新进展

文章基于深地震探测数据与大洋钻探资料,研究了南海北部被动陆缘洋陆转换带张裂–破裂机制科学问题。2018-2023年在国家基金委共享航次的协助下,实施了三维深地震探测实验,共投放海底地震仪52台次,海底电磁仪2台次,放炮数量达8750炮,累积获得了294Gb的第一手数据,并取得了一系列的创新性成果:1)首次获得南海北部陆缘洋陆转换带深达上地幔的三维速度结构,精准确定了研究区洋陆转换带三维空间展布范围宽度为10~20km;2)揭示南海北部陆缘异常活跃的岩浆作用,提出了不同时间段的构造与岩浆相互作用方式,岩浆活动随着伸展作用不断向洋迁移并逐渐占据主导地位;3)建立了边缘海独特的张裂–破裂地质演化模型,最后一期强烈的岩浆活动导致岩石圈破裂,形成由玄武岩为主的“鳄鱼嘴”构造,同时张裂–破裂过程沿其陆缘走向又存在显著的构造–岩浆差异性。

徐家围子断陷沙河子组主干断裂形成演化与地层剥蚀特征

主干断裂的活动控制着徐家围子断陷沙河子组的建造与改造。为了明确断裂活动,运用位移距离曲线方法系统分析了徐家围子断陷主干断裂的生长活动特征,通过不整合面下的同向轴特征分析了徐家围子断陷沙河子组沉积末期的剥蚀改造作用。结果表明:徐家围子断陷主干断裂分段特征明显,徐西断裂与宋西断裂在火石岭组沉积时期分别是数条分段的小断裂,在沙河子组沉积时期连通为整条断裂并持续控陷活动;徐中断裂在沙河子组沉积时期弱伸展弱控陷,在沙河子组沉积末期作为薄弱带发生压扭反转;徐东断裂带中的徐东正断层在沙河子组沉积时期弱控陷,徐东逆断层在营城组一段沉积末期的反转作用下形成;沙河子组沉积末期的反转作用对沙河子组厚度与构造格局产生明显改变,沿徐西断裂与宋西断裂存在较强的剥蚀,徐西断裂北端升平凸起尤为强烈,徐中断裂压扭反转产生一定的走滑分量并遭受剥蚀,徐东逆断层在营城组一段沉积末期的反转中形成,对沙河子组厚度无明显改变,但对徐东构造带构造格局产生明显影响。研究成果可为徐家围子断陷古构造恢复与进一步勘探提供理论参考。

重力——地震联合剥层预测石柱东部裂陷槽分布

石柱东部存在震旦—寒武系裂陷槽已经得到地震资料证实,但由于资料的局限性不能准确刻画裂陷槽展布特征。通过大量实测岩石样品和钻井资料分析研究,认识到石柱地区盐酸岩地层密度高,碎屑岩地层密度较低,且不同地层间存在一定的密度差,是重力资料研究深部结构良好的物性基础。因此在石柱地区开展了重力勘探工作,通过针对裂陷槽的重力—地震联合剥层反演技术,确定了石柱东部震旦—寒武系裂陷槽及深部断裂的分布特征。

Performance Evaluation of Low-Carbon and Clean Transformation of China’s Coal Economy

In China,the oversupply of coal occurred in 2009,and from that year onwards,China’s coal economy began a low-carbon and clean transformation.Evaluating transformation performance is the research goal of this paper.The data collection for this paper includes data on deep processing of Chinese coal products from 2009 to 2020,as well as data on asset structure evolution and financial performance of 34 listed companies in the Chinese coal mining.Entropy value method is used to calculate the entropy value of low-carbon transformation,and the regression analysis is used to study the performance of cleaner transformation,the conclusion is as follows:(1)From 2009 to 2020,in China’s total energy consumption,coal consumption accounted for 71.6%in 2009 and 56.8%in 2020,the goals set by the state have been achieved.(2)The national goal of reducing the proportion of coal consumption and reducing carbon emissions has forced the transformation of deep processing of coal products.The transformation of coal enterprises towards low-carbon and clean production has achieved remarkable results.(3)From 2009 to 2020,the non coal industry income of 34 listed companies in China’s coal mining industry increased by 8.21%annually.At the same time,the asset structure was adjusted,and nearly 80%of the asset structure evolution showed an orderly development trend.(4)The regression analysis results show that the entropy value of coal deep processing products and the entropy value of asset structure adjustment are significantly related to transformation performance.The paper proposes to summarize the successful experience of China’s coal energy economic transformation,lay a foundation for achieving the carbon peak and carbon neutral goals in the future,further increase the intensity of coal deep processing,increase the proportion of clean energy in total energy consumption,and strive to control asset operation towards the goal of increasing the proportion of non coal industry income.

New Knowledge-based Genetic Algorithm for Excavator Boom Structural Optimization

Due to the insufficiency of utilizing knowledge to guide the complex optimal searching, existing genetic algorithms fail to effectively solve excavator boom structural optimization problem. To improve the optimization efficiency and quality, a new knowledge-based real-coded genetic algorithm is proposed. A dual evolution mechanism combining knowledge evolution with genetic algorithm is established to extract, handle and utilize the shallow and deep implicit constraint knowledge to guide the optimal searching of genetic algorithm circularly. Based on this dual evolution mechanism, knowledge evolution and population evolution can be connected by knowledge influence operators to improve the conflgurability of knowledge and genetic operators. Then, the new knowledge-based selection operator, crossover operator and mutation operator are proposed to integrate the optimal process knowledge and domain culture to guide the excavator boom structural optimization. Eight kinds of testing algorithms, which include different genetic operators, arc taken as examples to solve the structural optimization of a medium-sized excavator boom. By comparing the results of optimization, it is shown that the algorithm including all the new knowledge-based genetic operators can more remarkably improve the evolutionary rate and searching ability than other testing algorithms, which demonstrates the effectiveness of knowledge for guiding optimal searching. The proposed knowledge-based genetic algorithm by combining multi-level knowledge evolution with numerical optimization provides a new effective method for solving the complex engineering optimization problem.

The tectonic differences between the east and the west in the deep-water area of the northern South China Sea

The deep-water area of the northern South China Sea, which has active and complicated tectonics, is rich in natural gas and gas hydrate. While the tectonic characteristics is different obviously between the east and the west because of the special tectonic position and tectonic evolution process. In terms of submarine geomorphology, the eastern shelf-slope structure in Pearl River Mouth Basin is characterized by having wide sub-basins and narrow intervening highs, whereas the western （Qiongdongnan Basin） structure is characterized by narrow sub- basins and wide uplift. As to the structural features, the deep-water sags in the east are all structurally half- grabens, controlled by a series of south-dipping normal faults. While the west sags are mainly characterised by graben structures with faulting in both the south and north. With regards to the tectonic evolution, the east began neotectonic activity when the post-rifting stage had completed at the end of the Middle Miocene. In the Baiyun Sag, tectonic activity became strong and was characterised by rapid subsidence and obvious faulting. Whereas in the west, neotectonic activity began at the end of the Late Miocene with rapid deposition and weak fault activity.

青海共和盆地结构构造与能源资源潜力

共和盆地处于西秦岭、南祁连、东昆仑造山带结合部,其中发现了高温干热岩及多套烃源岩,但地热藏和油气藏的成因、资源潜力与分布规律尚不清楚,难以对其开展准确评价和有效勘探开发。本文在系统研究共和盆地及周缘地层发育、沉积充填、构造变形与盆地深部结构的基础上,深入探讨了盆地演化的动力学机制,分析了盆地地热藏和油气藏的成藏主控因素,预测了有利分布区带和勘探方向。多期活动的哇洪山—温泉、多禾茂、瓦里贡、塘格木右行走滑逆冲断裂与青海南山左行走滑逆冲断裂异向、同向相交(切),叠加地幔上涌作用,导致在中新生代共和盆地长期处于走滑-伸展的独特环境,并控制了盆地7个隆起、断陷构造单元的展布及属性。它经历了6期演化阶段:早中三叠世处于昆北弧前盆地及陆缘火山弧带,共和盆地基底主要岩石发育;晚三叠世阿尼玛卿洋闭合并发生碰撞造山,共和盆地褶皱基底形成;晚三叠纪末期发生碰撞后伸展,发育初始小型陆内裂谷盆地;在侏罗纪—白垩纪区域性伸展环境下形成局部断陷盆地;古近纪晚期—中新世发育拉分-断陷盆地;中新世末至今发育陆内前陆盆地。形成了3个大构造-沉积层序和8个亚层序,发育了深海陆棚相-碳酸盐岩台地相-火成岩相以及多旋回的冲积扇-河流相-滨浅湖相-半深湖相等陆相沉积层序,它们记录了共和盆地的叠合发育演化及多期改造过程,与古特斯阿尼玛卿洋俯冲、后撤式俯冲、碰撞后伸展的近程效应响应,与班公-怒江、雅鲁藏布江新特提斯洋打开、俯冲、闭合以及印度/欧亚大陆碰撞过程的远程效应响应。共和盆地构造-沉积演化特色造就了盆地较好的油气和地热的能源资源条件。盆地发育有中下侏罗统羊曲组、下白垩统万秀组、新近系咸水河组和临夏组等三套烃源岩,可形成上-中-下三套潜力油气勘探层系,需进一步开展地层精细对比、区带评价和圈闭落实工作。共和盆地深部5层结构构造特征及盆地形成动力学过程揭示了其具有丰富的地热能资源潜力。幔源上涌驱动导致地壳内各层向上扰动,叠加走滑伸展的盆地发育环境,形成短路径-多源增热模式。地幔上涌、中下地壳局部熔融体提供了区域热源、局部热源;陆缘弧和碰撞相关花岗岩类叠加多期次断裂、裂缝及热液活动起到“控热储及热传导”作用;上覆巨厚细粒沉积岩阻热扩散而形成“控热盖”,是中高温干热岩型地热藏主控因素,也为浅层水热型地热的生成奠基。研究成果可为存在局部高大地热流的陆内中小型盆地地热藏研究提供借鉴。

中国石油海外岩性地层油气藏勘探进展与前景展望

通过中国石油走出去30年来海外大量勘探实例解剖,系统总结了岩性地层油气藏的勘探现状、分布特征和勘探模式,并指出了全球岩性地层油气藏的勘探前景及中国石油海外探区岩性地层油气藏的勘探潜力。研究结果表明:①全球岩性地层油气藏勘探经历了4个阶段,目前处于成熟发展阶段,大型深水沉积体和生物礁成为巨型岩性地层油气田发现的主要领域。②中国石油海外勘探新发现的岩性地层油气藏与全球岩性地层油气藏均主要分布在复合圈闭中,主要发育于前陆、裂谷和被动大陆边缘盆地,前者在裂谷盆地中发现的储量最多,前陆盆地次之,后者在前陆盆地中发现的储量最多,裂谷盆地次之。③中国石油海外实施构造和岩性地层油气藏同部署、同勘探策略,形成了3种特色高效的勘探模式,复式岩性地层油气藏立体勘探,发现了乍得邦戈尔盆地下组合高丰度岩性、高位潜山和低位潜山-岩性复合体油藏以及哈萨克斯坦南图尔盖盆地河道砂、扇三角洲、湖底扇和潜山等多类型岩性地层油气藏;复杂岩性体高精度三维地震勘探,发现了土库曼斯坦阿姆河盆地大型缓坡礁滩体气藏、巴西桑托斯盆地湖相礁滩体巨型油田以及缅甸若开次盆深水浊积砂岩生物气藏;薄层低幅度构造-岩性复合体地质工程一体化勘探,发现了南美奥连特盆地低幅度构造-岩性复合体油藏和中东阿曼次盆薄层礁滩体油藏。④全球岩性地层油气藏的勘探将从成熟探区拓展到低勘探程度的前沿领域、从陆上拓展到深水—超深水区,被动大陆边缘盆地深水沉积体、盆底扇和生物礁是岩性地层油气藏勘探的热点;裂岩盆地深层扇体、基岩潜山,前陆盆地和被动大陆边缘盆地礁滩体相关的复合圈闭是中国石油海外岩性地层油气藏勘探的主要对象,具有良好的前景。

基于多源信息表征的深部巷道围岩结构灾变演化机理

深部煤炭资源开采的强度和深度不断增加,深部巷道围岩的结构性失稳灾变问题日趋严峻、复杂,严重制约深部煤炭安全高效开采。鉴于深部巷道围岩结构变形失稳的渐进演化过程中释放多物理场响应信息,采用自主研制的深部地下工程结构变形失稳全过程模拟试验系统,配合声发射、并行电法、电磁辐射等监测系统,研究基于多源信息表征的深部巷道围岩结构灾变演化机理。开展了完整、层状和块状3种结构围岩的破坏性物理模型试验,利用声、电、磁多源信息演化规律对不同结构围岩的荷载-位移全过程进行了定量化评价和多源信息表征,从荷载-位移全程曲线、多源信息响应规律、围岩峰后损伤特性3个角度综合揭示了不同结构围岩的灾变演化及变形失稳机制。研究结果表明:(1)随着围岩完整性的降低,围岩由塑性破坏向脆性破坏转变,其变形破坏过程的波动性和渐进式破坏特征更加显著,层状和块状结构围岩的物理模型峰值承载能力相比于完整结构分别降低4.73%和20.73%;(2)与完整结构围岩的声、电、磁多源信息的连续性响应过程不同,层状和块状结构围岩呈现出阶段式响应规律且特征值更突出,尤其块状结构围岩的阶段跳跃性现象显著;(3)完整、层状和块状结构围岩的裂隙发育区面积依次为448.84、651.76和824.49 cm^(2),即随着围岩结构完整性的降低,裂隙发育区面积不断增大,在本研究中增大范围在1.5~1.9倍;(4)围岩的破坏失稳由完整结构的强度控制型向块状结构的结构控制型转变,而层状结构表现出强度-结构联合控制特征,围岩破坏失稳的结构效应越来越显著。

下扬子南部中新生代盆地差异演化特征

下扬子南部相邻的望江、怀宁、潜山3个中新生代盆地具有显著的差异演化特征。研究区深部约12 km发育个滑脱面,其上部的先存构造在伸展作用下发生活化,控制了盆地的结构、沉积填充和形成演化。中部的怀宁盆地属于晚侏罗—早白垩世岩浆活动上拱形成的裂陷盆地,沉积充填了套厚层的火山碎屑沉积。晚白垩世—古近纪时期.

深部煤层不同类型隐伏构造致灾规律研究

深部开采过程中,矿井地质类型复杂,在“三高一扰动”条件下,隐伏构造附近极易引发煤与瓦斯突出等煤岩动力灾害。为明确隐伏构造诱发动力灾害的机制,以平煤股份八矿为工程背景,数值模拟研究了不同采掘方向正、逆断层及两者同时存在时的应力-应变演化特征及致灾规律,分析了不同隐伏构造对掘进头的影响。结果表明:掘进遇单一断层,应力-应变集中在工作面前方及断层内部,掘进遇正断层更易产生应力集中,且应力集中区域范围更大,在同等掘进距离下,逆断层主应变略大于正断层;随着掘进距离的增加,当掘进距离增加至15 m时,应力-应变集中区逐渐重合,最终在断层区域形成应力-应变叠加区;掘进遇多断层,应力集中在工作面前方、两断层之间的构造煤上。遇正-逆断层、逆-正断层,叠加应力-应变分布特征表现出差异性,遇正-逆断层,叠加应力-应变主要分布在正断层附近,而遇逆-正断层,两断层之间构造煤中应力-应变也显著增加。逆断层及逆断层主导的多隐伏构造附近,应变能增长速率更大,更有利于应变能积聚,煤与瓦斯突出危险性增加。在采动应力、断层构造应力及煤岩体中的静应力三者的共同作用下,最终引发煤与瓦斯突出等煤岩动力灾害。多隐伏构造较单一构造更易产生应力集中,煤岩动力灾害危险性增加。

珠江口盆地番禺27洼裂陷期构造演化及其对源-汇系统的控制

番禺27洼位于珠江口盆地中央隆起带中部的番禺低隆起区,为发育在中生代陆缘岩浆弧基底之上“南断北超”的新生代凹陷,钻井取得的油样与砂岩储层抽提烃证实该洼陷存在文昌组中-深湖相烃源岩供烃,但已钻井均没有实际钻至文昌组,烃源岩发育的有利部位与有利时期仍存在不确定性。对控洼断裂系统及洼陷结构样式的研究表明,番禺27洼的发育和演化具有“先存构造约束、右旋伸展主控、岩浆底侵改造”三元耦合成因,控制了三幕裂陷阶段“左阶不对称地堑-左行雁列式半地堑-萎缩期宽缓半地堑”的结构样式。裂陷期三幕控洼断裂差异活化影响沉积中心变迁,洼陷结构差异演化影响洼陷沉积充填格局。随着裂陷期断裂活动的减弱,沉积中心逐渐由东向西、由两端向中部迁移。源-汇沉积体系在裂陷早期以NW轴向和中部转换带沉积体系为主,裂陷中期至裂陷晚期逐渐向北部缓坡大型沉积体系和西北部长轴优势沉积体系转换。西次洼长期作为沉积中心,是优质烃源岩发育的有利部位。裂陷中期发育大型半地堑式湖盆,并伴有较强的岩浆活动,是优质烃源岩发育的最有利时期。裂陷中期至裂陷晚期西北部大型源-汇沉积体系的长期发育为古近系大型储集体的形成提供了有利条件。

渤海湾盆地深层砂砾岩储层孔-缝成因机制及演化特征——以渤中19-6构造古近系孔店组为例

优质储层的识别和预测是深层-超深层碎屑岩储层油气勘探研究的重点。以渤海湾盆地渤中19-6构造古近系孔店组砂砾岩为研究对象,借助物理模拟实验等手段,研究了孔店组优质储集空间的成因及演化,建立了渤海湾盆地深层砂砾岩储层的孔-缝演化模式。取得的主要认识如下:①长石等颗粒的溶蚀孔为优质储集空间,钾长石的溶蚀随温度升高渐强甚至超过斜长石,钾长石在深层有更大的增孔潜力。②砾石级的颗粒、长英质的成分及低杂基含量更有利于压裂缝的产生,长石中压裂缝的发育程度要高于石英;垂向上,第一期压裂缝在2500 m左右的深度开始形成,第二期压裂缝在3000 m以深形成,而且其数量在4000 m左右的深度达到峰值,第三期压裂缝在4500 m以深开始形成,而且其数量随深度增大而逐渐增加。③孔隙度的垂向变化受到早期压实、晚期胶结以及中期溶蚀作用的控制。早期压实减孔17.38%;晚期铁白云石胶结减孔7.76%;有机酸溶蚀增孔5.45%。④油气充注与第二期溶蚀增孔及第一期和第二期压裂缝的发育相对应,油气在3000 m左右的深度处富集;4000 m以深压裂缝大量发育,叠加钾长石等溶蚀,预测深层砂砾岩中发育优质储层。