Effect of Shale Reservoir Characteristics on Shale Oil Movability in the Lower Third Member of the Shahejie Formation, Zhanhua Sag

To reveal the effect of shale reservoir characteristics on the movability of shale oil and its action mechanism in the lower third member of the Shahejie Formation(Es3l), samples with different features were selected and analyzed using N2 adsorption, high-pressure mercury injection capillary pressure(MICP), nuclear magnetic resonance(NMR), high-speed centrifugation, and displacement image techniques. The results show that shale pore structure characteristics control shale oil movability directly. Movable oil saturation has a positive relationship with pore volume for radius > 2 μm, as larger pores often have higher movable oil saturation, indicating that movable oil is present in relatively larger pores. The main reasons for this are as follows. The relatively smaller pores often have oil-wetting properties because of organic matter, which has an unfavorable effect on the flow of oil, while the relatively larger pores are often wetted by water, which is helpful to shale oil movability. The rich surface provided by the relatively smaller pores is beneficial to the adsorption of immovable oil. Meanwhile, the relatively larger pores create significant pore volume for movable oil. Moreover, the larger pores often have good pore connectivity. Pores and fractures are interconnected to form a complex fracture network, which provides a good permeability channel for shale oil flow. The smaller pores are mostly distributed separately;thus, they are not conducive to the flow of shale oil. The mineral composition and fabric macroscopically affect the movability of shale oil. Calcite plays an active role in shale oil movability by increasing the brittleness of shale and is more likely to form micro-cracks under the same stress background. Clay does not utilize shale oil flow because of its large specific surface area and its block effect. The bedding structure increases the large-scale storage space and improves the connectivity of pores at different scales, which is conducive to the movability of shale oil.

Hydrocarbon Reservoir Model of Glutenite in the Fourth Member of Shahejie Formation in Northern Dongying Depression

The glutenite in the fourth member of Shahejie Formation(Es^4) in northern Dongying depression straightforwardly penetrated into the muddy bathyal -abyss facies.The conditions of reservoir is very superior:(1) the high quality thick bedded oil source rock is developed very well in the Lijin sag and Minfeng sag of the study area,and it has the higher capability of generating hydrocarbon;(2) the

Basic characteristics of key interfaces in Upper Ordovician Wufeng Formation – Lower Silurian Longmaxi Formation in Sichuan Basin and its periphery,SW China

Based on anatomy of key areas and data points and analysis of typical features of shell layer in Guanyinqiao Member, basic characteristics of key interfaces, mainly bentonite layers, in the Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation in the Sichuan Basin and its surrounding areas and the relationship between these key interfaces with the deposition of organic-rich shale have been examined systematically. The Wufeng Formation-Longmaxi Formation has four types of marker beds with interface attributes, namely, the characteristic graptolite belt, Guanyinqiao Member shell layer, section with dense bentonite layers, and concretion section, which can be taken as key interfaces for stratigraphic division and correlation of the graptolite shale. The shell layer in Guanyinqiao Member is the most standard key interface in Wufeng Formation-Longmaxi Formation, and can also be regarded as an important indicator for judging the depositional scale of organic-rich shale in key areas. There are 8 dense bentonite sections of two types mainly occurring in 7 graptolite belts in these formations. They have similar interface characteristics with the shell layer in Guanyinqiao Member in thickness and natural gamma response, and belong to tectonic interfaces(i.e., event deposits). They have three kinds of distribution scales: whole region, large part of the region, and local part, and can be the third, fourth and fifth order sequence interfaces, and have a differential control effect on organic-rich shale deposits. The horizon the characteristic graptolite belt occurs first is the isochronous interface, which is not directly related to the deposition of organic-rich shale. Concretions only appear in local areas, and show poor stability in vertical and horizontal directions, and have no obvious relationship with the deposition of the organic-rich shale.

Syndepositional Fault Controlling on Depositional Filling of the Third Member of Shahejie Formation in Beitang Sag

In the continental lake basin whose structures were extraordinarily active, tectonism is an important factor in controlling the sequence and the depositional filling of the basin. This article reports the assemble patterns of syndepositional fault in the third member of Shahejie （沙河街） Formation in Beitang （北塘） sag. The results show that the comb-shape fracture system and the fracture transformation zone were developed in Beitang sag. These assemble patterns obviously controlled the sand-body and spatial distribution of sedimentary system. However, the steep slope belt of fault terrace, the multistage slope belt and the low uplift gentle slope belt controlled the development of sequence styles. Analyses of the spatial-temporal relationship of the assemble pattern of syndepositional faults and the sedimentary system help predict the favorable exploration zone.

Key geological factors controlling the estimated ultimate recovery of shale oil and gas: A case study of the Eagle Ford shale, Gulf Coast Basin, USA

Based on 991 groups of analysis data of shale samples from the Lower Member of the Cretaceous Eagle Ford Formation of 1317 production wells and 72 systematic coring wells in the U.S. Gulf Basin, the estimated ultimate recovery(EUR) of shale oil and gas of the wells are predicted by using two classical EUR estimation models, and the average values predicted excluding the effect of engineering factors are taken as the final EUR. Key geological factors controlling EUR of shale oil and gas are fully investigated. The reservoir capacity, resources, flow capacity and fracability are the four key geological parameters controlling EUR. The storage capacity of shale oil and gas is directly controlled by total porosity and hydrocarbon-bearing porosity, and indirectly controlled by total organic carbon(TOC) and vitrinite reflectance(Ro). The resources of shale oil and gas are controlled by hydrocarbon-bearing porosity and effective shale thickness etc. The flow capacity of shale oil and gas is controlled by effective permeability, crude oil density, gas-oil ratio, condensate oil-gas ratio, formation pressure gradient, and Ro. The fracability of shale is directly controlled by brittleness index, and indirectly controlled by clay content in volume. EUR of shale oil and gas is controlled by six geological parameters: it is positively correlated with effective shale thickness, TOC and fracture porosity, negatively correlated with clay content in volume, and increases firstly and then decreases with the rise of Ro and formation pressure gradient. Under the present upper limit of horizontal well fracturing effective thickness of 65 m and the lower limit of EUR of 3×10^(4) m^(3), when TOC<2.3%, or Ro<0.85%, or clay content in volume larger than 25%, and fractures and micro-fractures aren’t developed, favorable areas of shale oil and gas hardly occur.

断陷湖盆细粒区页岩组构特征与页岩油富集成藏规律:以黄骅坳陷古近系为例

为明确断陷湖盆细粒区页岩微观组构特征及页岩油富集成藏规律,基于黄骅坳陷古近系孔二段、沙三段、沙一段3套页岩层系取心、测井、录井及试油等资料,综合利用矿物分析-场发射扫描电镜、氩离子抛光-场发射扫描电镜、聚焦离子束-场发射扫描电镜等技术手段,针对页岩样品开展多尺度、多维度精细表征,从微观、定量的角度系统分析了页岩矿物、有机质、孔隙及页岩油赋存特征,揭示了页岩油成藏富集规律并建立了富集模式。研究结果表明:在微观视域下,多类型矿物以“组分混合”和“组构叠置”构成复杂页岩类型;储集空间可划分为无机孔隙、有机孔隙和微裂缝3大类9小类,其中无机孔隙贡献率平均可达85%以上,孔径<50 nm的孔隙占据储集空间的主体;微观上有机质可划分为同沉积有机质、交生分异有机质和运移充填有机质3种类型;烃类主要赋存于长英质纹层、灰云质纹层或粉砂岩纹层中。基于矿物、有机质、储集空间、烃类4个要素的“四元耦合”页岩油富集成藏规律,建立了3类富集成藏模式。在该模式指导下,沧东凹陷孔二段实施多口水平井获高产,优质页岩油区块已经实现当今油价下的效益开发,歧口凹陷沙三段及沙一下亚段页岩油均获得重要突破,展示出黄骅坳陷古近系页岩油具有广阔的资源前景。

川中中台山地区致密砂岩储层层序特征及有利区优选

川中中台山地区须三下亚段(须三下)层序构成差异性明显、河流相砂体横向变化较快,层序地层划分较为困难,进而影响优质储层的识别与刻画。为此,基于测井、录井和地震资料,分析中台山地区须三下层序特征,圈定不同朵页体的分布范围,对储层有利区进行优选。结果表明:川中中台山地区须三下地层沉积继承了须二上亚段的地层特征,为东南高西北低、洼中隆的缓坡古构造背景,共识别出3期层序界面和2期湖泛面;致密砂岩储层矿物组分主要为岩屑和长石,孔隙类型以溶蚀孔隙、微裂缝为主;岩性组合主要有厚层砂岩组合、厚层砂夹薄层泥岩组合和厚层泥夹薄层砂岩组合三大类;结合高产井具有断裂、裂缝、储层发育,位于构造相对高部位的特征,将研究区储层划分为3类有利区。研究成果可为后续的勘探开发提供重要参考和理论支撑。

Tight oil accumulation of the redeposited carbonates in the continental rift basin:A case study from Member 3 of Shahejie Formation in Shulu sag of Jizhong depression,North China

Tight oil in the redeposited carbonates was mainly distributed in the Lower Submember of Member 3 of Shahejie Formation in Shulu sag of Jizhong depression,North China.Through high-resolution 3D seismic data,well logging data and drilling data,the Lower Submember of Member 3 of Shahejie Formation was divided into 5 third-order sequences and 15 parasequence sets.The redeposited marl and rudstone were major reserving horizons of tight oil,and ten reserving space types were developed and could be classified into two main categories,i.e.,pores and fractures.Two types of tight oil reservoirs were established,i.e.,the marl hydrocarbon reservoir of the source-reservoir integration and the rudstone hydrocarbon reservoirs of the source-reservoir paragenesis.The assemblage relationship among the high-quality source rocks,system tracts with the source-reservoir configuration was the major control factor for tight oil accumulation in the redeposited carbonates.The lacustrine transgressive system tracts and highstand systems tracts in SQ1 to SQ5 were the favorable horizons for development of the marl hydrocarbon reservoir,the lowstand system tracts in SQ1 to SQ3 were the favorable horizons for development of the rudstone hydrocarbon reservoir.

Space-Time Evolution and Controlling Factor of Fine-Grained Sediments in the Upper Fourth Member of Shahejie Formation, Dongying Depression

Fine-grained rocks（FGR） are the important source rocks and reservoirs of shale hydrocarbon which is the prospect hotspot at present. Widely distributed fine-grained sediments（FGS） of the upper fourth member of Shahejie Formation in Dongying depression are taken as an example to study the space-time evolution and controlling factor of FGS in this paper. Based on the analysis of well cores, thin sections, inorganic and organic geochemistry indicators, FGR are divided into 7 types of lithofacies. Through the study of ‘point-line-plane＇, this study shows that FGS has the characteristics of rhythum, diversity and succession. The first stage is characterized by clayey FGS（massive claystone）. The second stage is characterized by carbonate FGS（low-TOC laminated limestone） and dolomitic FGS（dolomitic-silty shale） formed by transgression. The third stage is characterized by organic-rich carbonate FGS（middle/high-TOC laminated limestone） distributed in cycle. The fourth stage is characterized by FGS mixed carbonate and siliciclastic sediments（calcareous-silty shale）. A variety of space-time evolution of FGS are controlled by multiple factors including tectonism, climate and lake conditions.

渤海湾盆地庙西北地区古近系沙河街组三段源-汇系统重建

基于钻井岩心和三维地震资料,从物源岩性、分水岭和古水系、搬运通道3个方面对渤海湾盆地庙西北地区物源特征和沉积相展布进行了分析,并通过沉积区古地貌恢复和剥蚀物源区古地貌回溯重建了古近系沙河街组三段(沙三段)沉积时期的源-汇系统。研究结果表明:(1)渤海湾盆地庙西北地区古近系沙三段发育一个完整的近源搬运型源-汇系统,庙西北凸起为物源区,渤东凹陷为主要沉积区;庙西北凸起物源岩性包括中生界花岗岩、下元古界石英片岩及下元古界角砾岩;主分水岭沿凸起长轴呈近南北向展布,古水系散布其间,搬运通道主要为5个古沟谷和2个古断槽;渤东凹陷沙三段主要发育快速堆积的扇三角洲—湖泊相沉积,岩性主要为含砾砂岩、细砂岩及泥岩,分选性和磨圆度均较差,岩石成分及矿物组合均与庙西北凸起石英片岩及花岗岩较为匹配,扇三角洲沉积体呈近东西向展布,在渤东凹陷北部以连片朵状扇三角洲为主,南部为孤立朵状。(2)沙三段沉积期,庙西北凸起剥蚀作用具有“西强东弱”的特征,古分水岭逐渐向西迁移,凸起中部及北部物源面积大、垂向高差大,物源供给能力更强;渤东凹陷沙三段厚度为100~600 m,具有东南薄、西北厚的特征,沉积中心位于区域北部,且北部地层剥蚀作用更强,向东部延伸长度可达3.2 km;扇三角洲的发育位置受控于物源区搬运通道,其发育规模则受控于物源区域面积,渤东凹陷北部及中部扇三角洲沉积体规模更大,是勘探有利区。

川中地区大安寨段页岩热演化史及油气地质意义

下侏罗统自流井组大安寨段为四川盆地陆相页岩油开发的最有利层段,页岩油勘探潜力巨大,然而对该地层的热演化史缺乏系统研究。利用含油气盆地模拟系统,对比分析了川中地区北部与中部大安寨段页岩热演化及生烃差异,并探讨其对页岩油富集的影响。研究区大安寨段页岩现今热演化程度由西南向东北逐渐增高,平面上可分为高成熟区和成熟区。高成熟区位于研究区北部,镜质体反射率为1.3%~1.7%,主要发育Ⅲ型有机质,在晚侏罗世早期进入早期生油阶段,晚侏罗世末达到生烃高峰,存在2期生烃作用;成熟区位于研究区中—南部,镜质体反射率为0.9%~1.3%,主要发育Ⅱ1型—Ⅱ2型有机质,侏罗系沉积厚度相对较小,有机质成熟时期较晚,晚侏罗世末进入早期生油阶段,早白垩世进入生烃高峰,仅有1期生烃过程。相较于北部地区,中部地区沉积了大套的富有机质页岩,是大安寨段页岩油坚实的物质基础,但古近纪以来的构造抬升与地层剥蚀,对该区的油气保存具有一定的破坏作用。

松辽盆地西南部姚家组下段局部排泄源特征及与铀矿化关系分析

松辽盆地西南部上白垩统姚家组下段含水层是重要的铀矿化区域。为了深入了解该地区的铀成矿机制,文章采用水文地质分析、放射性元素含量测定、水化学特征分析等手段,结合区域构造和含水层结构研究,对姚家组下段局部排泄源及其与铀矿化的关系进行了深入研究。研究揭示了姚家组下段具备完整的补给-径流-排泄体系;补给区大面积发育潜水氧化带,径流区发育层间氧化带;更重要的是,确定了局部排泄源为隐伏排泄源,并发现含矿含水层地下水向上部第四系含水层排泄过程中,在局部排泄源区域引起了一系列水文地质特征的变化。局部排泄源的空间存在对铀矿化形成具有控制作用,这为松辽盆地西南部铀矿的进一步勘探提供了重要的理论依据。

渤海湾盆地辽中凹陷北部东营组沉积体系发育演化与构造古地貌的控制作用

根据地震和钻、测井资料,识别渤海湾盆地东北部辽中凹陷北部东营组中下段地震相和岩相组合类型,揭示沉积体系的发育演化规律;拉平古水平面,恢复东营组沉积时期构造古地貌,探讨构造古地貌对沉积体系发育演化的控制作用。结果表明:辽中凹陷北部东营组中下段可识别6种地震相与9种岩相组合类型,发育辫状河三角洲、曲流河三角洲、湖底扇以及碎屑湖泊等沉积,北部由辫状河三角洲演变为双向供源的曲流河三角洲-湖底扇,中南部早期发育小型辫状河三角洲并逐渐消亡,南部小型辫状河三角洲逐渐向北推进;东营组中下段沉积期研究区整体南高北低,可划分辽东凸起和辽中凹陷2个隆坳单元,进一步识别断裂陡坡带、缓坡断阶带、缓坡带、古沟谷等构造古地貌单元;研究区发育的沉积体系类型及规模与古坡折坡度、凹陷沉降中心位置、古沟谷规模密切相关,沉积体系的分布演化是盆地隆坳格局、坡折地貌形态、古沟谷发育位置与物源供给方向共同作用的结果。该结果对研究区油气勘探有利砂体预测具有指导意义。

陆相断陷咸化湖盆细粒沉积地层有机质富集特征及控制因素分析——以东营凹陷沙河街组第四段上亚段纯上次亚段为例

【目的】湖相细粒沉积泥页岩储层“甜点段”的发育与有机质富集密切相关,但目前针对断陷咸化湖盆泥页岩有机质富集控制因素的探究及富集模式的建立等相关研究较少。【方法】东营凹陷沙河街组第四段上亚段纯上次亚段(Es4scs)时期发育典型的陆相断陷咸化湖盆,为深化对研究该区细粒沉积地层有机质富集规律的认识。从沉积学、地球化学、古生物学及分子地层学等方面入手,利用薄片鉴定、X射线衍射、氩离子抛光—扫描电镜、孢粉鉴定、生物标志物色谱—质谱分析等技术手段,运用各项指标详细探究有机质富集的控制因素,建立适用于研究区各环境演化阶段的有机质富集模式。【结果】(1)有机质具有条带状、充填式、分散式等微观赋存状态,母质来源主要为藻类等低等水生生物,在中上部地层出现少量的陆源高等植物来源;(2)沉积环境经历了较浅水半干旱弱氧环境—深水半湿润还原环境—次深水半干旱贫氧环境三个演化阶段;(3)有机质富集的主要控制因素为古气候、古盐度、古氧化还原性、古生产力和沉积速率,而次要控制因素为古水深、陆源输入、火山作用和热液活动。【结论】本次探究了有机质富集的主控因素,建立了适用于陆相断陷咸化湖盆细粒沉积地层的有机质富集模式,研究成果对我国陆相页岩油气勘探开发具有重要意义,即高生产力、还原环境、适宜的盐度和沉积速率主导了高有机质富集,该环境的沉积产物是页岩油气勘探的有利层段。

四川盆地蓬莱—中江地区震旦系灯影组二段成藏特征

通过钻井、岩心、测录井及地震资料的综合分析,系统研究了四川盆地蓬莱—中江地区震旦系灯影组二段气藏的成藏特征。研究结果表明:(1)四川盆地灯影组沉积期,随着海水侵入,古陆多被淹没或侵蚀夷平,盆地逐渐演变为碳酸盐岩台地。灯二上亚段沉积期,川中北斜坡蓬莱—中江地区以发育台地边缘滩相和台地边缘丘相为特色,并可细分为滩核、滩缘、滩间海、丘核、丘缘、丘间海6种亚相,是储层发育的有利相带。(2)研究区灯二上亚段储层以藻云岩、藻砂屑云岩为主要储集岩,发育残余粒间孔+粒间溶孔型、粒内溶孔+藻格架孔型、裂缝型与孔洞型4种类型的储层,储层厚度分布特征与沉积相分布特征较吻合,位于台地边缘丘滩核的储层累积厚度大。(3)研究区灯二上亚段气藏的天然气主要来源于筇竹寺组烃源岩,烃源岩厚度大、有机碳含量及热演化程度高,气藏具备较好的烃源条件和封盖条件,具有“上生下储上盖”和“旁生侧储上盖”2种较好的生-储-盖配置关系。(4)研究区油气充注主要发生于三叠纪—白垩纪,为多期“准连续”型,灯二上亚段气藏主要经历了奥陶纪—志留纪古油气藏聚集阶段、志留纪—石炭纪古油藏破坏阶段、二叠纪—三叠纪再次生烃成油藏阶段和三叠纪—侏罗纪原油裂解生气阶段。

源外层系油气运聚关键环节研究与评价方法——以渤海湾盆地渤中凹陷明化镇组下段为例

油气运聚是源外层系规模性成藏的关键之一。利用渤海湾盆地渤中地区丰富的三维地震和钻井数据分析,从断裂带深层垂向输导、馆陶组二次汇聚及明化镇组下段(明下段)侧向分流3个主要运聚环节分析入手,对明下段砂体烃柱高度进行分析。研究认为,烃源超压-断层活动耦合作用是断裂带垂向输导的关键,在烃源充足条件下断裂带分形维数大于0.7时,油气垂向输导能力较强;富砂型层系形成的早期油藏控制油气二次汇聚能力,利用馆陶组圈闭面积和有效幅度等计算汇聚系数,当馆陶组汇聚系数大于700 km3时,对应明下段具备发育大、中型油田的基础;断层的泄压控制浅层砂体侧向分流环节,利用砂体高部位和低部位断-砂接触面积计算泄压系数,当明下段砂体泄压系数大于2.0时,砂体烃柱高度可超过30 m。3个主要运聚环节紧密配合,是富生烃凹陷源外层系高丰度油藏形成的必要条件。

东营凹陷深层自源型油气成藏模式与勘探实践

东营凹陷深层是以“红层”为典型特征的沙河街组四段下亚段(沙四下亚段)—孔店组,该套层系沉积厚度大、储量发现少,蕴含着极大的勘探潜力。综合深层烃源岩评价、高成熟油源对比及自源型油气成藏模式的系统分析,明确了深层沙四下亚段和孔店组二段(孔二段)两套烃源岩的基本特征,落实了深层的资源潜力,同时深入剖析关键成藏要素条件,建立了自源型差异油气成藏模式。研究表明,深层孔二段烃源岩有机质类型为Ⅱ_(1)—Ⅲ型,评价为过成熟中等烃源岩;沙四下亚段烃源岩有机质类型为Ⅰ—Ⅱ_(1)型,评价为成熟优质烃源岩。利用原型盆地的井—震追踪落实烃源岩展布,进而评价出深层资源量为11.35×10^(8)t。同时,建立了两种自源型油气藏的差异成藏模式,一种是陡坡带沙四下亚段烃源岩直接对接深层砂砾岩储层,匹配形成凝析油气—常规油的纵向有序油气藏;另一种是南部斜坡带孔店组源内的“源—断—储—圈”差异油气运聚模式。分析认为,基于东营凹陷深层烃源岩品质与规模的深化认识,以及两种自源型油藏模式的认识可将勘探目的层至少下探1500m,初步估算新增圈闭资源量近2×10^(8)t,东营凹陷深层自源型油藏预计在“十四五”期间迎来重大突破。

渤海湾盆地歧口凹陷古近系沙三段页岩油储层非线性渗流特征

通过高压压汞与低温气体吸附实验,结合核磁共振在线检测系统和驱替实验,对渤海湾盆地歧口凹陷古近系沙三段页岩油储层的渗流特征进行了研究。研究结果表明:①歧口凹陷古近系沙三段3种岩相页岩的微孔数量占比最大。与块状泥岩相比,纹层状及层状页岩储层的孔径大于100 nm的中大孔喉更为发育,储集性及渗流能力更优。②赋存在页岩储层大孔喉中的可流动油能有效产出,但由于渗流阻力较大,微小孔喉(小于100 nm)中的油即使在很大压差下也难以产出。③页岩储层中的石油渗流具有启动压力梯度和非线性渗流的特征,但不同岩相的渗透特征差异较大,其中纹层状页岩拟启动压力梯度最小,渗流能力最强,层状页岩储层具有一定的渗流能力,块状页岩储层渗流能力最差。在相同压力梯度下,块状页岩中的流量仅为纹层状页岩中流量的10%左右,基本无自然产能。

不同孔隙结构碳酸盐岩的岩石物理响应特征及储层预测新方法——以鄂尔多斯盆地奥陶系马家沟组四段为例

近年来,在鄂尔多斯盆地中东部地区下奥陶统马家沟组四段(以下简称马四段)的台内丘滩体钻遇了优质白云岩储层,但该套储层厚度薄、与围岩弹性参数差异较小,利用常规方法很难准确识别和预测。为了提高白云岩储层的预测精度,基于铸体薄片与岩心CT扫描,详细分析了马四段碳酸盐岩的特征,通过岩石物理弹性测试,结合物性测试及试采资料建立了马四段岩石弹性参数与孔隙结构的关系,提出了研究区一种变基质多孔微分等效介质模型的预测孔隙结构和储层的新方法,并进行了矿场验证。研究结果表明:(1)马四段碳酸盐岩发育孔隙型和裂缝型2类储层,其中孔隙型储层可细分为以晶间孔为主和以晶间溶孔+晶间孔为主2类;(2)晶间孔为白云岩化作用形成,孔隙纵横比较大,晶间溶孔由晶间孔经过溶蚀作用改造形成,孔隙纵横比变小;(3)裂缝主要为构造缝和溶蚀缝,孔隙纵横比最小;(4)沉积和成岩作用对碳酸盐岩的孔隙结构影响大,孔隙结构的差异会引起岩石弹性参数的较大变化,利用该差异可以有效预测白云岩优质储层。结论认为,该方法首先通过变基质骨架建模准确划分岩石的基质类型,然后利用多重孔微分等效介质模型预测岩石的孔隙结构类型,并定量计算不同孔隙类型孔隙的体积占比,为提高白云岩储层的预测精度奠定了技术基础,有助于碳酸盐岩优质储层的精确预测的深入研究。

松辽盆地南部海力锦铀矿床姚家组下段黏土矿物特征及其铀成矿意义

黏土矿物是表征盆地砂岩型铀矿含矿建造地球化学环境以及反演其经历的表生流体作用的重要指示性矿物。文章以钱家店凹陷新发现的海力锦铀矿床含矿层姚家组下段为研究对象,通过偏光显微镜、X射线衍射、扫描电镜及能谱分析等方法,系统开展了不同地球化学分带的岩石学、黏土矿物类型、形貌及含量等特征研究。姚家组下段红色和灰色泥岩原生黏土矿物组合为伊利石+伊蒙混层,高岭石含量较低,总体反映了沉积期偏干旱炎热古气候环境。泥岩中不同类型黏土矿物含量具有一定的相关性,推测其在沉积-成岩过程中存在一定的相互转化关系。与泥岩明显不同,各地球化学分带砂岩中的黏土矿物主要为高岭石,其次为伊利石和伊蒙混层,显示具有后生外来酸性流体改造的特点,应发生在区域层间氧化水渗入之前。铀含量与黏土矿物含量间没有明显的相关性,结合镜下铀-黏土矿物空间赋存关系和区内构造-流体演化史显示,矿石中铀沉淀富集受多种吸附还原剂控制,局部与高岭石关系密切,存在一期深部酸性还原流体渗出改造作用,为原生偏弱还原性的姚家组下段砂岩铀成矿提供了有利条件。