Genesis of granular calcite in lacustrine fine-grained sedimentary rocks and its indication to volcanichydrothermal events: A case study of Permian Lucaogou Formation in Jimusar Sag, Junggar Basin, NW China

Granular calcite is an authigenic mineral in fine-grained sedimentary rocks.Core observation,thin section observation,cathodoluminescence analysis,fluid inclusion analysis,scanning electron microscope(SEM),and isotopic composition analysis were combined to clarify the genesis of granular calcite in the lacustrine fine-grained sedimentary rocks of the Permian Lucaogou Formation in the Jimusar Sag,Junggar Basin.It is found that the granular calcite is distributed with laminated characteristics in fine-grained sedimentary rocks in tuffite zones(or the transitional zone between tuffite and micritic dolomite).Granular calcite has obvious cathodoluminesence band,and it can be divided into three stages.Stage-Ⅰ calcite,with non-luminesence,high content of Sr element,inclusions containing Cos,and homogenization temperature higher than 170℃,was directly formed from the volcanic-hydrothermal deposition.Stage-Ⅱ calcite,with bright yellow luminescence,high contents of Fe,Mn and Mg,enrichment of light rare earth elements(LREEs),and high homogenization temperature,was formed by recrystallization of calcareous edges from exhalative hydrothermal deposition.Stage-IlI calcite,with dark orange luminescence band,high contents of Mg,P,V and other elements,no obvious fractionation among LREEs,and low homogenization temperature,was originated from diagenetic transformation during burial.The granular calcite appears regularly in the vertical direction and its formation temperature decreases from the center to the margin of particles,providing direct evidences for volcanic-hydrothermal events during the deposition of the Lucaogou Formation.The volcanic-hydrothermal event was conducive to the enrichment of organic matters in fine-grained sedimentary rocks of the Lucaogrou Formation,and positive to the development of high-quality source rocks.The volcanic-hydrothermal sediments might generate intergranular pores/fractures during the evolution,creating conditions for the self-generation and self-storage of shale oil.

Prediction of multiscale laminae structure and reservoir quality in fine-grained sedimentary rocks:The Permian Lucaogou Formation in Jimusar Sag,Junggar Basin

Fine-grained sedimentary rocks have become a research focus as important reservoirs and source rocks for tight and shale oil and gas.Laminae development determines the accumulation and production of tight and shale oil and gas in fine-grained rocks.However,due to the resolution limit of conventional logs,it is challenging to recognize the features of centimeter-scale laminae.To close this gap,complementary studies,including core observation,thin section,X-ray diffraction(XRD),conventional log analysis,and slabs of image logs,were conducted to unravel the centimeter-scale laminae.The laminae recognition models were built using well logs.The fine-grained rocks can be divided into laminated rocks(lamina thickness of<0.01 m),layered rocks(0.01-0.1 m),and massive rocks(no layer or layer spacing of>0.1 m)according to the laminae scale from core observations.According to the mineral superposition assemblages from thin-section observations,the laminated rocks can be further divided into binary,ternary,and multiple structures.The typical mineral components,slabs,and T2spectrum distributions of various lamina types are unraveled.The core can identify the centimeter-millimeter-scale laminae,and the thin section can identify the millimeter-micrometer-scale laminae.Furthermore,they can detect mineral types and their superposition sequence.Conventional logs can identify the meter-scale layers,whereas image logs and related slabs can identify the laminae variations at millimeter-centimeter scales.Therefore,the slab of image logs combined with thin sections can identify laminae assemblage characteristics,including the thickness and vertical assemblage.The identification and classification of lamina structure of various scales on a single well can be predicted using conventional logs,image logs,and slabs combined with thin sections.The layered rocks have better reservoir quality and oil-bearing potential than the massive and laminated rocks.The laminated rocks’binary lamina is better than the ternary and multiple layers due to the high content of felsic minerals.The abovementioned results build the prediction model for multiscale laminae structure using well logs,helping sweet spots prediction in the Permian Lucaogou Formation in the Jimusar Sag and fine-grained sedimentary rocks worldwide.

Lithofacies and Pore Structure of Fine-grained Sedimentary Rocks of Qing-1 Member of Cretaceous in the Southern Songliao Basin

Fine-grained sedimentary rocks often contain hydrocarbon and mineral resources.Compared with coarse-grained sedimentary rocks,fine-grained sedimentary rocks are less studied.To elucidate the lithofacies and pore structure of lacustrine fine-grained rocks,the 340.6 m continuous core of Cretaceous Qing-1 Member from five wells in the southern central depression of the Songliao Basin was analyzed using X-ray diffraction,Rock-Eval pyrolysis,low-temperature nitrogen adsorption,high-pressure mercury injection,argon ion polishing-field emission scanning electron microscopy,and laser scanning confocal microscopy.Based on mineral compositions,organic matter abundance and sedimentary structure,lacustrine fine-grained rocks in the study area were divided into ten lithofacies,with their spatial distributions mainly influenced by tectonic cycle,climate cycle and provenance.Furthermore,pore structure characteristics of different lithofacies are summarized.(1)The siliceous mudstone lithofacies with low TOC content and the laminated/layered claybearing siliceous mudstone lithofacies with medium TOC content have the highest proportion of first-class pores(diameter>100 nm),making it the most favourable lithofacies for the accumulation of shale oil and shale gas.(2)The massive claybearing siliceous mudstone lithofacies with low TOC content has the highest proportion of second-class pores(diameter ranges from 10 to 100 nm),making it a favourable lithofacies for the enrichment of shale gas.(3)The massive clay-bearing siliceous mudstone lithofacies with high TOC content has the highest proportion of third-class pores(diameter<10 nm),making it intermediate in gas storage and flow.Laser confocal oil analysis shows that the heavy component of oil is mainly distributed in the clay lamina,while the light part with higher mobility is mainly concentrated in the silty lamina.

Bedding parallel fractures in fine-grained sedimentary rocks:Recognition,formation mechanisms,and prediction using well log

Core,thin section,conventional and image logs are used to provide insights into distribution of fractures in fine grained sedimentary rocks of Permian Lucaogou Formation in Jimusar Sag.Bedding parallel fractures are common in fine grained sedimentary rocks which are characterized by layered structures.Core and thin section analysis reveal that fractures in Lucaogou Formation include tectonic inclined fracture,bedding parallel fracture,and abnormal high pressure fracture.Bedding parallel fractures are abundant,but only minor amounts of them remain open,and most of them are partly to fully sealed by carbonate minerals(calcite)and bitumen.Bedding parallel fractures result in a rapid decrease in resistivity,and they are recognized on image logs to extend along bedding planes and have discontinuous surfaces due to partly-fully filled resistive carbonate minerals as well as late stage dissolution.A comprehensive interpretation of distribution of bedding parallel fractures is performed with green line,red line,yellow line and blue line representing bedding planes,induced fractures,resistive fractures,and open(bedding and inclined)fractures,respectively.The strike of bedding parallel fractures is coinciding with bedding planes.Bedding parallel fractures are closely associated with the amounts of bedding planes,and high density of bedding planes favor the formation of bedding parallel fractures.Alternating dark and bright layers have the most abundant bedding parallel fractures on the image logs,and the bedding parallel fractures are always associated with low resistivity zones.The results above may help optimize sweet spots in fine grained sedimentary rocks,and improve future fracturing design and optimize well spacing.

Discussion on classification and naming scheme of fine-grained sedimentary rocks

Based on reviews and summaries of the naming schemes of fine-grained sedimentary rocks, and analysis of characteristics of fine-grained sedimentary rocks, the problems existing in the classification and naming of fine-grained sedimentary rocks are discussed. On this basis, following the principle of three-level nomenclature, a new scheme of rock classification and naming for fine-grained sedimentary rocks is determined from two perspectives: First, fine-grained sedimentary rocks are divided into 12 types in two major categories, mudstone and siltstone, according to particle size(sand, silt and mud). Second,fine-grained sedimentary rocks are divided into 18 types in four categories, carbonate rock, fine-grained felsic sedimentary rock,clay rock and mixed fine-grained sedimentary rock according to mineral composition(carbonate minerals, felsic detrital minerals and clay minerals as three end elements). Considering the importance of organic matter in unconventional oil and gas generation and evaluation, organic matter is taken as the fourth element in the scheme. Taking the organic matter contents of 0.5% and 2% as dividing points, fine grained sedimentary rocks are divided into three categories, organic-poor, organic-bearing,and organic-rich ones. The new scheme meets the requirement of unconventional oil and gas exploration and development today and solves the problem of conceptual confusion in fine-grained sedimentary rocks, providing a unified basic term system for the research of fine-grained sedimentology.

Multi-source genesis of continental carbonate-rich fine-grained sedimentary rocks and hydrocarbon sweet spots

This paper systematically discusses the multiple source characteristics and formation mechanisms of carbonate-rich fine-grained sedimentary rocks through the analysis of material source and rock formation.The hydrocarbon accumulation characteristics of carbonate-rich fine-grained sedimentary rocks are also summarized.The results show that the main reason for the enrichment of fine-grained carbonate materials in rift lake basins was the supply of multiple material sources,including terrestrial material input,formation of intrabasinal authigenic carbonate,volcanic-hydrothermal material feeding and mixed source.The development of carbonate bedrock in the provenance area controlled the filling scale of carbonate materials in rift lake basins.The volcanic-hydrothermal activity might provide an alkaline fluid to the lake basins to strengthen the material supply for the formation of carbonate crystals.Authigenic carbonate crystals induced by biological processes were the main source of long-term accumulation of fine-grained carbonate materials in the lake basins.Carbonate-rich fine-grained sedimentary rocks with multiple features were formed through the interaction of physical,biochemical and chemical processes during the deposition and post-deposition stages.The source and sedimentary origin of the fine-grained carbonate rock controlled the hydrocarbon accumulation in it.In the multi-source system,the types of"sweet spots"of continental shale oil and gas include endogenous type,terrigenous type,volcanic-hydrothermal type and mixed source type.

四川盆地元坝地区千佛崖组二段细粒沉积岩岩相特征及储集性分析

四川盆地侏罗系千佛崖组页岩油气勘探前景良好,但目前对其细粒沉积岩基本沉积特征及发育规律的认识还不足。为此,利用细粒沉积学原理,依据岩心和测井资料,通过岩心精细描述、薄片鉴定、X衍射全岩分析及扫描电子显微镜观察等技术手段,精细描述了元坝地区千佛崖组二段(简称千二段)细粒沉积岩储层的物质组成、沉积构造、储集空间类型等地质特征,划分了岩相类型,并对主要岩相储层的物性特征和储集空间类型进行分析与比较,明确了有利层段发育位置。研究结果显示:(1)千二段陆相细粒沉积岩可划分成“黏土岩”和“粉砂岩”2种岩石类型,15种岩相类型。其中,富有机质块状黏土岩、富有机质块状含粉砂黏土岩、富有机质纹层状含粉砂黏土岩、富有机质条带状含粉砂黏土岩、富有机质块状粉砂质黏土岩和富有机质纹层状粉砂质黏土岩为6种主要岩相类型。(2)储层储集空间类型多样,包括黏土矿物层间缝、层理缝、黏土矿物晶间孔、黄铁矿晶间孔、溶蚀孔及有机孔等,其中黏土矿物晶间孔分布最为广泛。(3)6种主要岩相的平均孔隙度和渗透率分别为2%和0.023×10^(-3)μm^(2),富有机质纹层状含粉砂黏土岩、富有机质纹层状粉砂质黏土岩和富有机质块状粉砂质黏土岩的储集空间类型丰富,分布广、数量多,孔隙度与渗透率均高于其他岩相且TOC值较高,是最有利的储集岩相类型。(4)千二段有利层段位于其(1)小层全段、(2)小层的底部和(3)小层的中下部。

牛庄洼陷沙四上—沙三下亚段细粒沉积岩成分与纹层结构的关系

湖相细粒沉积岩的纹层发育,但纹层的厚度、密度、连续度等结构特征变化很大,这些变化与细粒沉积岩的沉积环境密切相关。利用图像分析的手段,对牛庄洼陷沙四上—沙三下亚段细粒沉积岩纹层的厚度、密度、侧向连续性进行定量表征,并与细粒沉积岩的各种物质成分对比研究。结果表明:牛庄洼陷沙四上—沙三下亚段细粒沉积岩的纹层厚度、密度、侧向连续性与长英质、黏土、碳酸盐等矿物质量分数基本没有相关性,纹层密度与有机碳含量具有一定的正相关性,长英质矿物与黏土矿物质量分数具有明显的正相关性;牛庄洼陷沙四上—沙三下亚段细粒沉积岩的沉积速率越低,越有利于有机碳含量的提高;长英质矿物与黏土矿物主要是洪水以表层流、层间流的形式一起搬运到深湖环境沉积下来的;湖泊表层碳酸盐矿物的产生与沉淀,与水体深度、沉积速率没有关系,也不存在湖相碳酸盐补偿界面(CCD)。

Classification of Hydrocarbon-Bearing Fine-Grained Sedimentary Rocks

Fine-grained sedimentary rocks are defined as rocks which mainly compose of fine grains（〈62.5 μm）. The detailed studies on these rocks have revealed the need of a more unified, comprehensive and inclusive classification. The study focuses on fine-grained rocks has turned from the differences of inorganic mineral components to the significance of organic matter and microorganisms. The proposed classification is based on mineral composition, and it is noted that organic matters have been taken as a very important parameter in this classification scheme. Thus, four parameters, the TOC content, silica（quartz plus feldspars）, clay minerals and carbonate minerals, are considered to divide the fine-grained sedimentary rocks into eight categories, and the further classification within every category is refined depending on subordinate mineral composition. The nomenclature consists of a root name preceded by a primary adjective. The root names reflect mineral constituent of the rock, including low organic（TOC〈2%）, middle organic（2%4%） claystone, siliceous mudstone, limestone, and mixed mudstone. Primary adjectives convey structure and organic content information, including massive or limanited. The lithofacies are closely related to the reservoir storage space, porosity, permeability, hydrocarbon potential and shale oil/gas sweet spot, and are the key factor for the shale oil and gas exploration. The classification helps to systematically and practicably describe variability within fine-grained sedimentary rocks, what＇s more, it helps to guide the hydrocarbon exploration.

陆相细粒沉积岩岩相组合类型划分研究现状及其油气地质意义

细粒沉积岩是陆相页岩油气重要的烃源岩和储集层。然而该类岩石具有岩相类型多样、垂向叠置复杂的特征,已知大部分获得高产油气井对应的甜点层通常为多种岩相类型的组合。当前,细粒沉积岩岩相分类方案仍存在分歧,岩相组合相关研究尚处于初步阶段。通过对比近年来国内学者关于陆相细粒沉积岩岩相类型划分方案的差异性,梳理了岩相组合的划分依据,探寻岩相组合划分新方法及其研究的油气地质意义。认为在岩相类型识别基础上,开展天文旋回理论指导下的岩相组合类型划分、展布特征刻画,对于陆相页岩油甜点精细预测具有重要意义;分析不同岩相组合源-储耦合特征、油气分布特征,注重微运移的相关研究有助于提升对页岩油气差异性富集的认识。

细粒沉积岩测井评价研究进展

细粒沉积岩是致密油气、页岩油气的烃源岩层和储集层,是石油地质研究的重点和前沿领域,测井评价细粒沉积岩在非常规油气勘探开发中具有非常重要的意义。通过系统分析国内外细粒沉积岩测井评价技术进展,研究认为:细粒沉积岩在常规测井基础上结合新技术测井开展了岩性、物性、电性、含油性、可动性、润湿性、脆性、烃源岩特性和地应力各向异性等“七性+”特性评价。进一步发展为细粒沉积岩储集性、含油性、可动性和可压性“新四性”评价方法。依据岩性、岩相、孔隙类型和微观孔隙结构、页理、总孔隙度和有效孔隙度等参数评价细粒沉积岩储集性。根据黏土矿物分布、TOC、游离烃含量、含油饱和度、赋存状态及可动油量等参数评价细粒沉积岩含油性。通过成熟度、地层压力、原油密度、原油黏度及气/油比等参数评价细粒沉积岩油可动性。依据黏土矿物成分和含量、脆性矿物成分和含量、杨氏模量、泊松比及最大和最小主应力等参数评价细粒沉积岩可压性。通过成像测井切片技术实现细粒沉积岩米级、毫米级甚至微米级纹层的人工识别与评价。用测井资料开展细粒沉积岩岩相识别与评价。细粒沉积岩测井从常规测井法、新技术测井法向基于数学统计的人工智能法发展。

陆相断陷咸化湖盆细粒沉积岩特征及沉积环境——以泌阳凹陷核桃园组H3Ⅲ亚段为例

泌阳凹陷作为国内典型的陆相断陷咸化湖盆,在古近系核桃园组三段广泛发育细粒沉积岩。文中利用长井段连续取心资料以及薄片观察、二维XRF扫描、XRD分析、扫描电镜以及地球化学测试等手段,以矿物组分、沉积构造和粒度作为主要依据,把泌阳凹陷H3Ⅲ亚段细粒沉积岩划分为9种岩相类型,其中纹层状混合质页岩、纹层状长英质页岩是发育类型最多的细粒沉积岩;通过Mg/Ca、Al含量、Ti含量、(Fe+Al)/(Ca+Mg)、P/Ti、Sr/Ba和V/(V+Ni)等地球化学指标的垂向变化及岩相组合来分析沉积环境的演化特征。泌阳凹陷H3Ⅲ亚段沉积环境是半深湖—深湖环境,水体盐度为半咸水—咸水,陆源输入总体较强,气候变化相对较大,从下到上经历了干旱、干湿交替、湿润以及干旱的气候变化。岩相的垂向变化受气候、陆源输入、水深、水体盐度的影响,气候、陆源输入、水深决定了长英质矿物和黏土矿物的含量,而碳酸盐矿物的含量主要受到水体盐度和气候的影响。

湖相细粒沉积岩颗粒微观力学特征及类型划分——以鄂尔多斯盆地上三叠统延长组7段页岩为例

细粒沉积岩蕴藏着丰富的油气资源,为了研究细粒沉积岩颗粒微观结构及力学特征,以鄂尔多斯盆地上三叠统延长组7段细粒沉积岩为例,开展了扫描电镜观察和纳米压痕实验分析,据此研究细粒沉积颗粒的几何特征和微观力学性质。研究认为:用粒径、扁平度、棱角性、硬度和弹性模量5个特征参数,可将细粒沉积岩划分为粒度+棱角型、扁平度+棱角型、扁平度+棱角+弹性模量+硬度型、弹性模量+硬度型、棱角+弹性模量+硬度型和粒度+棱角+弹性模量型6种主要颗粒类型;接着,根据颗粒类型的相对含量,进一步将颗粒类型划分为5种组合类型;最后,分析了细粒沉积颗粒类型与矿物类型之间的耦合关系。细粒沉积岩颗粒微观分类方案的建立,有助于理解细粒沉积岩微观结构特征,预测地质“甜点”空间分布,对细粒沉积岩的油气资源评价和效益开发具有重要的理论和科学意义。

陆相混合细粒岩沉积微相及其对甜点的控制作用——以吉木萨尔凹陷芦草沟组为例

【目的】吉木萨尔凹陷二叠系芦草沟组发育了一套陆相混积沉积体系,混积细粒岩沉积微相类型及甜点储层分布规律等研究的不足制约了该区页岩油高效开发。【方法】综合岩心、露头、测井、X射线荧光光谱(X-Ray Fluorescence,XRF)元素录井、分析化验和试油试采等资料,采用岩相构型、沉积微相耦合分析和动静结合等方法,开展了沉积微环境及微相类型划分、沉积模式及其对甜点的控制作用等研究。【结果】(1)研究区主要发育浪成交错层理、水平层理、同生变形构造、黄铁矿、方解石条带、鸟眼构造和结核、缝合线构造、含生物化石和白云岩溶蚀孔8类沉积构造。研究区分为半深湖—深湖、混合浅湖和碎屑浅湖亚相,细分为半深湖泥、云坪、混合滩坝、混合浅湖泥、浅湖砂坝和碎屑浅湖泥等6种微相,不同微相沉积特征及其沉积机制差异明显。(2)建立了咸化湖泊相混积细粒岩沉积微相模式。芦一段自下而上从深湖—半深湖—浅湖演化过程,发育了浅湖砂坝、混合滩坝与云坪微相。其中,云坪呈连片状大范围分布,混合滩坝呈土豆状分布,发育程度较高,不同层规模有差异,浅湖砂坝发育程度一般,呈断续状局限分布,垂向上呈薄储集层与厚层泥岩叠置状。芦二段以浅湖为主,微相类型与芦一段类似,但形态、规模与叠置样式差异较大。云坪和混合滩坝发育数量和规模大大减小,浅湖砂坝则发育程度较高,呈大规模分散土豆状发育,垂向上呈厚层叠置状。不同位置剖面微相的叠置样式不同。(3)甜点段XRF元素分析显示,目的层沉积时为干燥炎热的半咸水环境到咸水过渡环境,古生产力水平较高;下甜点段为富氧环境,上甜点段则为厌氧亚还原到还原环境。(4)沉积微相控制了甜点分布和开发对策。混合滩坝微相Ⅰ类甜点发育程度高,非均质性弱,开发效果最好,采用大规模部署水平井平台化作业进行效益开发。云坪微相Ⅲ类甜点发育,非均质性强,开发效果一般,是后续接替区域。浅湖砂坝Ⅱ类甜点发育,整体分散状,连续性较差,非均质性强,开发效果较好。【结论】后续应在沉积微相空间分布精细研究基础上,参考核磁曲线参数部署水平井开发。

陆相咸化湖盆细粒沉积岩分类及其石油地质意义

细粒沉积岩作为地壳表层最多的岩石类型,蕴藏着丰富的油气资源,是近些年油气工业领域研究的一个热点。由于细粒沉积岩主要由粒径小于0.0625 mm的颗粒或晶体构成,成分多样复杂,导致其岩石类型术语运用混乱,该问题在陆相湖盆细粒沉积岩研究中尤为突出。为了建立科研人员之间清晰、高效的沟通渠道,提出一套三级命名分类方案,由大到小分别为沉积构造、结构与成分、盐组分。首先,按沉积构造分为层状细粒沉积岩和块状细粒沉积岩;然后,根据沉积结构和成分,划分出7种主要岩石类型;最后,根据盐组分再划分陆相湖盆不同演化阶段的岩石类型。该方案基于描述性的属性作为分类的标准,分级逐级描述,具有反映物源、水动力条件、咸化湖盆演化等成因意义。陆相湖盆细粒沉积岩的岩石学分类,不仅有助于理解细粒沉积岩层系中生烃母质类型和丰度的层位归属及演变,而且有助于预测地质“甜点”空间分布等,对细粒沉积岩的油气资源评价、科学优选目标、提升勘探开发整体效益等具有重要的理论和实践意义。

基于物质来源及成因的细粒沉积岩分类方案探讨

细粒沉积岩分类对细粒沉积岩系统深入研究至关重要,分类方案应当反映岩石组分物质来源、沉积作用方式,且具有广泛适用性。细粒沉积岩物质来源多样,包括陆源碎屑来源、盆内化学沉淀来源、生物源、火山碎屑来源。不同盆地细粒沉积岩的物质来源存在巨大差异,同一盆地同种矿物也通常具有成因多样性。细粒沉积岩作为一种特殊岩石类型,综合考虑物质来源和沉积作用方式,笔者提出了细粒沉积岩四组分三端元分类方案,根据有机质含量分为高、中、低3大类,以陆源碎屑物质、内源化学沉淀物质、火山碎屑物质进行三端元划分,分为4类:陆源碎屑细粒岩类、化学细粒岩类、火山碎屑细粒岩类、混合细粒岩类;并根据三级命名原则、合并命名原则、复合命名原则,分为11个亚类,岩石名称可根据岩石组分的相对含量进行命名。

Sedimentary environment and petrological features of organic-rich fine sediments in shallow water overlapping deposits: A case study of Cambrian Yuertus Formation in northwestern Tarim Basin, NW China

Taking the Cambrian Yuertus Formation outcrop profiles in the Aksu-Keping-Wushi areas of northwestern Tarim Basin as examples, the depositional environments of organic rich fine sediment were analyzed by examining the outcrop profiles macroscopically and microscopically. The study reveals that:(1) The lower part of the Yuertus Formation consists of organic-rich fine sediment or thin rhythmic interbeds of organic-rich fine sediment and siliceous sediment, the formation transforms to terrigenous diamictic grain shoal and inverse grading carbonate rocks upward.(2) The thin limestone interbedded with dark shale rhythmically has inverse grading.(3) The thin-bedded siliceous rock has metasomatic residual granular texture, stromatolithic structure and cementation fabric in vugs.(4) There are iron crust layers at the top of the shallowing diamictic grain shoal, beneath which exposed karst signs, such as karrens, dissolved fissures, sack-like vugs, near surface karst(plastic) breccia, breccia inside the karst system and terrigenous clastic fillings, can be seen.(5) Both the outcrops and seismic profiles show that organic-rich fine sediments above the unconformities or exposed surfaces are characterized by overlapping. The organic-rich fine sediment of the Cambrian Yuertus Formation was deposited in the anoxic-suboxidized restricted gulf lagoon environment, and its formation was controlled by high paleoproductivity and poor oxygen exchange jointly, then a shallow-water overlapping sedimentary model has been established. The results will help enrich and improve the sedimentary theory of organic-rich fine sediments.

东濮凹陷古近系沙河街组页岩油储层岩石学及微观孔隙结构特征

泥页岩的岩石学及微观孔隙结构特征是评价页岩油气储集性能的关键指标。通过岩心观察、薄片鉴定、扫描电镜、压汞-液氮吸附联合测定及微米CT三维重构等实验分析,对东濮凹陷沙河街组页岩油储层的岩石学特征、岩相类型、孔缝类型、孔喉分布及含油性特征等进行研究。实验分析结果表明,东濮页岩油储层矿物组分主要为黏土矿物、碳酸盐矿物,含有少量长英质矿物,主要的岩相类型包括纹层状灰岩相、纹层状黏土岩相、纹层状灰质细粒混合岩相、纹层状黏土质细粒混合岩相、块状黏土岩相和块状白云岩相;储集空间包括晶间孔、粒内溶蚀孔、黏土矿物晶间孔及有机质孔,微裂缝可分为成岩缝和构造缝,纹层状灰岩相和纹层状灰质细粒混合岩相的储集空间类型多样,储集空间相对较大。岩相和层理构造是影响储层孔隙发育及优劣的重要因素,纹层状灰质细粒混合岩、纹层状灰岩相及纹层状黏土质细粒混合相孔隙尺寸大,孔喉连通性较好,裂缝较为发育,同时具有好的含油性及可动性,其中以纹层状灰岩相最优,它们是东濮凹陷页岩油重点勘探对象。

烟雾峁地区延长组深湖细粒沉积岩岩相特征

为研究细粒沉积岩的分布、深湖的岩相划分和储层评价,寻找有利区带,选取鄂尔多斯盆地延长组长7深湖细粒沉积岩进行矿物含量、有机质含量及沉积结构等岩性特征分析,建立量化分类方案。结果表明:细粒沉积岩可分为富有机质层状页岩相、富有机质凝灰质条带泥岩相、富有机质层状泥岩相、富有机质层状粉砂质泥岩相、含有机质层状细砂岩相和含有机质块状砂岩相6种岩相类型,分别具有“一高四中一低”“两高两中两低”“一高三中两低”“五中一低”“四中两低”和“一中五低”等测井曲线特征;烟雾峁地区长7段为含有机质层状细砂岩相和含有机质块状砂岩相,物性较好,有利于致密油的聚集。分析烟雾峁致密油藏岩相特征,推测油藏有利岩相,建立不同类型的岩相,为缺乏岩芯资料井段的岩相识别提供思路。

天文旋回在页岩油勘探及富有机质页岩地层等时对比中的应用

地球演化过程中存在着不同尺度旋回性,其时间跨度可以由一天至数亿年。地球轨道周期驱动的轨道尺度的沉积旋回,是目前定量化地层划分对比研究最好的时间尺度选择。富有机质页岩的连续性使得轨道尺度的天文旋回更容易保存,而米氏旋回的“时间内涵”是进行地层等时对比的有效手段,可以对富有机质页岩进行高精度的地层划分和对比。本文以中国东部渤海湾盆地东营凹陷页岩油勘探的主力烃源岩层段为例,利用地球轨道周期实现陆相富有机质页岩多尺度地层等时对比,相关研究具有重要的科学和页岩油勘探指导意义。以斜率作为地层划分与对比的基本单元,实现东营凹陷富有机质页岩六级层序等时对比,误差小于4万年。通过天文年代标尺的区域对比,明确东营凹陷页岩油高产层段时间为42.85~41.85 Ma,在E2-E4这3个长偏心率周期范围内,与斜率周期的高振幅段恰巧吻合,推测其与斜率周期驱动的纹层状页岩发育所导致的页岩油高产有关。地球轨道周期具有较高的时间分辨率且较容易识别,万年级的年代框架为陆相页岩高精度等时对比提供了可能,可为页岩油勘探中优质烃源岩层段预测提供精细年代框架。