Depositional Environment and Lithofacies Analyses of Eocene Lacustrine Shale in the Bohai Bay Basin:Insights from Mineralogy and Elemental Geochemistry

The effect of various depositional parameters including paleoclimate,paleosalinity and provenance,on the depositional mechanism of lacustrine shale is very important in reconstructing the depositional environment.The classification of shale lithofacies and the interpretation of shale depositional environment are key features used in shale oil and gas exploration and development activity.The lower 3rd member of the Eocene Shahejie Formation(Es_(3)^(x)shale)was selected for this study,as one of the main prospective intervals for shale oil exploration and development in the intracratonic Bohai Bay Basin.Mineralogically,it is composed of quartz(avg.9.6%),calcite(avg.58.5%),dolomite(avg.7%),pyrite(avg.3.3%)and clay minerals(avg.20%).An advanced methodology(thin-section petrography,total organic carbon and total organic sulfur contents analysis,X-ray diffraction(XRD),X-ray fluorescence(XRF),field-emission scanning electron microscopy(FE-SEM))was adopted to establish shale lithofacies and to interpret the depositional environment in the lacustrine basin.Six different types of lithofacies were recognized,based on mineral composition,total organic carbon(TOC)content and sedimentary structures.Various inorganic geochemical proxies(Rb/Sr,Ca/(Ca+Fe),Ti/Al,Al/Ca,Al/Ti,Zr/Rb)have been used to interpret and screen variations in depositional environmental parameters during the deposition of the Es_(3)^(x)shale.The experimental results indicate that the environment during the deposition of the Es_(3)^(x)shale was warm and humid with heightened salinities,moderate to limited detrital input,higher paleohydrodynamic settings and strong oxygen deficient(reducing)conditions.A comprehensive depositional model of the lacustrine shale was developed.The interpretations deduced from this research work are expected to not only expand the knowledge of shale lithofacies classification for lacustrine fine-grained rocks,but can also offer a theoretical foundation for lacustrine shale oil exploration and development.

济阳坳陷沙四段上亚段—沙三段下亚段泥页岩层理结构特征及储集性控制因素

济阳坳陷沙四段上亚段—沙三段下亚段泥页岩具有复杂的成分及结构非均质性,对其储集性控制因素尚不明确,制约了页岩油勘探进展。利用岩石薄片分析等资料将研究区以富碳酸盐为特征的泥页岩分为A—J共10种层理结构类型,以B—D类最为发育,所占比例达80%;利用岩石薄片、氩离子抛光-扫描电镜对泥页岩基质孔隙类型进行观察与综合分析,认为研究区孔隙类型主要有刚性颗粒间孔、有机质及黏土矿物收缩孔和碳酸盐晶间孔。从层理结构类型来看,G,H,B和D类储集性较好,其次为E和F类,A和C类较差,其他类型储集性更差。分析不同类型层理结构泥页岩储集性控制因素发现:碳酸盐呈泥晶结构的泥页岩,矿物成分对孔隙发育程度具有主导控制作用;碳酸盐呈晶粒结构(包含柱纤结构)的泥页岩,层理结构对储集性的控制作用较强。根据泥页岩出油井段分析结果,指出下步应以寻找碳酸盐含量为30%～50%的G,H,B和D类层理结构泥页岩为主要勘探方向,优选碳酸盐含量满足上述条件且G和H类层理结构泥页岩层段。

济阳坳陷页岩油储层物质组分对含油性的控制规律

借助岩石学和地球化学分析手段,对济阳坳陷沙四段上亚段和沙三段下亚段页岩油储层进行原油赋存状态和物质组分分析。荧光特征分析结果表明:束缚型和游离型沥青分别选择性赋存于泥质纹层、碳酸盐纹层和裂缝内,泥质纹层作为生油的母质仓储,易于富集炭质沥青和沥青质沥青;碳酸盐纹层相对于泥质纹层具有更优越的储集空间,易于富集胶质沥青和油质沥青,更易流动的油质沥青则汇集到裂缝内。研究发现,方解石脉本质上是一种接近于完全充填的裂缝表现形式,总结出4个亮晶方解石脉体的识别标志,其中轴愈合线附近的方解石晶间孔和未愈合缝可以作为油质沥青的运移通道。页岩油储集空间的发育主要受控于岩石结构与构造及物质组分,矿物组分差异和有机质热演化是页岩油储集空间和含油性的2个主要影响因素。受此影响,泥页岩储集性表现为:(1)纹层状泥页岩储层具有高孔隙度;(2)碳酸盐含量高的泥页岩储层具有高孔隙度;(3)高有机质热演化程度的泥页岩储层具有高孔隙度。

济阳坳陷古近系沙河街组湖相富有机质页岩白云石成因及成岩演化

通过岩石学、X衍射全岩成分分析、稳定碳氧同位素组成分析,以及微量元素和稀土元素组成分析,对济阳坳陷古近系沙河街组页岩中白云石的成因进行研究。结果表明,研究区沙河街组湖相富有机质页岩中的白云岩发育规模小,可识别出3种白云石矿物:原生白云石(D1)、准同生白云石(D2)和铁白云石(Ak)。D1具有原生球形白云石的结构,高镁高钙,白云石有序度为0.3~0.5,且普遍具有外缘次生加大现象和内核溶蚀孔共存的特征;D2有序度为0.5~0.7,具有次生加大、高镁高钙和含铁锰元素的特点;Ak具有高有序度(0.7~0.9)、菱形晶、高镁、高钙和高铁的特征。在利用碳氧同位素组成和稀土元素分馏特征佐证泥晶方解石为原生成因的基础上,根据共生白云石和泥晶方解石之间的氧同位素组成分馏方程,计算得到研究区页岩中白云石的形成温度为36.76~45.83℃,属于湖相低温白云石。此外,基于原生和准同生白云石晶体的熟化生长机制,恢复了与研究区沙河街组湖相页岩成岩环境相对应的白云石成岩序列和白云石化作用进程。

Origin and diagenetic evolution of dolomites in Paleogene Shahejie Formation lacustrine organic shale of Jiyang Depression,Bohai Bay Basin,East China

The origin of dolomite in Shahejie Formation shale of Jiyang Depression in eastern China were studied by means of petrologic identification, compositional analysis by X-ray diffraction, stable carbon and oxygen isotopic composition, and trace element and rare earth element analyses. The results show that the development of dolomite is limited in the lacustrine organic rich shale of Shahejie Formation in the study area. Three kinds of dolomite minerals can be identified: primary dolomite(D1), penecontemporaneous dolomite(D2), and ankerite(Ak). D1 has the structure of primary spherical dolomite, high magnesium and high calcium, with order degree of 0.3-0.5, and is characterized by the intracrystalline corrosion and coexistence of secondary enlargement along the outer edge. D2 has the characteristics of secondary enlargement, order degree of 0.5-0.7, high magnesium, high calcium and containing a little iron and manganese elements. Ak is characterized by high order degree of 0.7-0.9, rhombic crystal, high magnesium, high calcium and high iron. The micritic calcite belongs to primary origin on the basis of the carbon and oxygen isotopic compositions and the fractionation characteristics of rare earth elements. According to the oxygen isotopic fractionation equation between paragenetic dolomite and calcite, it is calculated that the formation temperature of dolomite in the shale is between 36.76-45.83 ℃, belonging to lacustrine low-temperature dolomite. Based on the maturation and growth mechanism of primary and penecontemporaneous dolomite crystals, a dolomite diagenetic sequence and the dolomitization process are proposed, which is corresponding to the diagenetic environment of Shahejie Formation shale in the study area.

船舶压载水处理装置远程监测系统设计与开发

针对船舶压载水处理装置缺乏实时远程监测系统,在出现故障以及需要维护时,工程师必须到达现场才能确认故障并解决。文章提出一种压载水处理装置远程监测系统,通过智能网关与可编程逻辑控制器(Programmable Logic Controller,PLC)连接实现对压载水装置的远程监测,可以实现设备监测、程序更新以及参数可视化等功能,大大节省了现场服务成本。

东营凹陷古近系湖相细粒混积岩沉积成岩特征

东营凹陷古近系湖相细粒混合沉积岩相类型、沉积环境和成岩演化等方面有待深入研究,利用岩心观察、薄片、X衍射和碳氧同位素等分析手段,明确了细粒混积岩相类型和沉积成岩特征.研究认为:岩石矿物组分和古生物含量的纵向变化较好地反映了沉积环境的变化和混合沉积成因过程,可作为细粒沉积层序四级界面识别标志.泥晶和亮晶方解石经历过显著的碳氧同位素分馏,证实了混积岩中泥晶方解石主要隶属于与甲烷细菌活动生成生物气有关的碳酸盐,透镜状和纹层状亮晶方解石纹层源自脉体方解石充填微裂缝,微裂缝和方解石脉集中形成于早期次干气-生油阶段.阐述了从生烃增压、微裂缝形成、有机质热演化排出有机酸、溶蚀泥晶方解石、方解石重结晶和脉体形成,直至影响临近砂体胶结作用的整个同生演化过程,对中深层页岩油气成藏研究具有重要指导意义.