Source of silica and its implications for organic matter enrichment in the Upper Ordovician-Lower Silurian black shale in western Hubei Province,China:Insights from geochemical and petrological analysis

To improve the understanding of the relationship between silica source and organic matter accumulation,the origin of silica and its implications for organic matter enrichment in the Upper OrdovicianLower Silurian(O_(3)w-S_(1)l)black shale in western Hubei Province in the middle Yangtze area,were investigated through geochemical and petrological analyses.The results show that the O_(3)w-S_(1)l black shale is mainly composed of five lithofacies with varying graptolite abundance,total organic carbon(TOC),and silica contents.Biogenic silica and terrigenous siliciclastic input constitute the main silica sources in O_(3)w-S_(1)l black shale and they exhibit an upward inverse variation trend interpreted to be related to sea-level changes.Moreover,with the increase in biogenic silica content or decrease in terrigenous siliciclastic input,TOC values in black shale initially rise and then fall,which is different from originally expected simple linear relationship.We infer that organic matter enrichment and the distribution of silica from different origins are controlled by sea-level changes and variations in terrigenous input in a continental shelf with little hydrothermal influence.An environment with appropriate sea level and terrigenous input should be most favorable for organic matter accumulation,rather than one with excessive high sea level and less terrigenous input.

Investigation of gas content of organic-rich shale:A case study from Lower Permian shale in southern North China Basin,central China

Measuring gas content is an essential step in estimating the commerciality of gas reserves. In this study,eight shale core samples from the Mouye-1 well were measured using a homemade patented gas desorption apparatus to determine their gas contents. Due to the air contamination that is introduced into the desorption canister, a mathematical method was devised to correct the gas quantity and quality.Compared to the chemical compositions of desorbed gas, the chemical compositions of residual gas are somewhat different. In residual gas, carbon dioxide and nitrogen record a slight increase, and propane is first observed. This phenomenon may be related to the exposure time during the transportation of shale samples from the drilling site to the laboratory, as well as the differences in the mass, size and adsorptivity of different gas molecules. In addition to a series of conventional methods, including the USBM direct method and the Amoco Curve Fit(ACF) method, which were used here for lost gas content estimation, a Modified Curve Fit(MCF) method, based on the 'bidisperse' diffusion model, was established to estimate lost gas content. By fitting the ACF and MCF models to gas desorption data, we determined that the MCF method could reasonably describe the gas desorption data over the entire time period, whereas the ACF method failed. The failure of the ACF method to describe the gas desorption process may be related to its restrictive assumption of a single pore size within shale samples. In comparison to the indirect method, this study demonstrates that none of the three methods studied in this investigation(USBM, ACF and MCF) could individually estimate the lost gas contents of all shale samples and that the proportion of free gas relative to total gas has a significant effect on the estimation accuracy of the selected method. When the ratio of free gas to total gas is lower than 45%, the USBM method is the best for estimating the lost gas content, whereas when the ratio ranges from 45% to 75% or is more than 75%, the ACF and MCF methods, are the best options respectively.

A rock physics model for the characterization of organic-rich shale from elastic properties

Kerogen content and kerogen porosity play a significant role in elastic properties of organic-rich shales. We construct a rock physics model for organic-rich shales to quantify the effect of kerogen content and kerogen porosity using the Kuster and Toks6z theory and the selfconsistent approximation method. Rock physics modeling results show that with the increase of kerogen content and kerogen-related porosity, the velocity and density of shales decrease, and the effect of kerogen porosity becomes more obvious only for higher kerogen content. We also find that the Poisson＇s ratio of the shale is not sensitive to kerogen porosity for the case of gas saturation. Finally, for the seismic reflection responses of an organic-rich shale layer, forward modeling results indicate the fifth type AVO re- sponses which correspond to a negative intercept and a positive gradient. The absolute values of intercept and gradient increase with kerogen content and kerogen porosity, and present predictable variations associated with velocities and density.

Activity of Silica-Rich Hydrothermal Fluid and Its Impact on Deep Dolomite Reservoirs in the Sichuan Basin, Southern China

Well-developed dissolution pores occur in the dolomites of the Sinian Dengying Formation, which is an important oil and gas reservoir layer in the Sichuan Basin and adjacent areas in southern China. The pores are often filled with quartz, and some dolomites have been metasomatically altered to siliceous chert. Few studies have documented the characteristics, source or origin of silica-rich fluids and their effects on the dolomite reservoir. The peak homogenisation temperatures （Th） of fluid inclusions in pore-filling quartz are between 150~C and 190~C, with an average of 173.7~C. Gases in the inclusions are mainly composed of CO2, CH4 and N2. Compared with host dolomite, pore-filling quartz and metasomatic chert contain higher amounts of Cr, Co, Mo, W and Fe, with average concentrations of 461.58, 3.99, 5.05, 31.43 and 6666.83 ppm in quartz and 308.98, 0.99, 1.04, 13.81 and 4703.50 ppm in chert, respectively. Strontium levels are lower than that in the host dolomite, with average concentrations in quartz and chert of 4.81 and 11.06 ppm, respectively. Rare earth element compositions in quartz and chert display positive Eu anomalies with a maximum δEu of 5.72. The δDsMow values of hydrogen isotopes in water from quartz inclusions vary from -85.1‰ to -53.1‰ with an average of-64.3‰, whereas the δ18OsMow values range from 7.2‰ to 8.5‰ with an average of 8.2‰. The average 87Sr/86Sr ratios in quartz and chert are 0.711586 and 0.709917, respectively, which are higher than that in the host dolomite. The fluid inclusions, elemental and isotopic compositions demonstrate that the formation of quartz and chert was related to silica-rich hydrothermal fluid and that the fluid was the deep circulation of meteoric water along basement faults. Interactions with silica-rich hydrothermal fluids resulted in densification of dolomite reservoirs in the Dengying Formation through quartz precipitation and siliceous metasomatism. However, it increased the resistance of the host dolomite to compaction, improving the ability to maintain reservoir spaces during deep burial. Evidence for silica-rich hydrothermal activity is common in the Yangtze Platform and Tarim Basin and its influence on deep dolomite reservoirs should be thoroughly considered.

Organic Richness and Organic Matter Quality Studies of Shale Gas Reservoir in South Sumatra Basin, Indonesia

Talang Akar Formation is a proven hydrocarbon source rock in South Sumatra basin. The formation contains dominant shale at the top, with some sandstone interbeds. Whereas it contains coarse to very coarse sandstone beds at the bottom. The lower sandstone unit also contains carbonaceous shale and some coal seams. The geochemical analysis is important to identify a source rock quality in shale gas. The quality of source rock is determined by richness of the source rock and type of kerogen. 37 samples were collected from well cuttings in JML-1 and JML-2 wells. Samples we are received into the laboratories in the form of well site canned ditch cuttings, bagged ditch cuttings in various stages of preparation from wet, unwashed to dried, washed;sidewall cores, conventional cores, outcrop samples. The richness of a source rock can be defined by the content of organic carbon which is measured as total organic carbon (TOC). Based on geochemical result of analysis, quantity of shale hydrocarbon potential is indicated by the TOC value of 0.52 wt% - 6.12 wt% (fair to excellent criteria), with average of shale thickness more than 50 m. Tmax is an indication of the maturation stage of organic material and Hydrogen Index (HI) is a parameter used to explain the origin of organic material. HI versus Tmax crossplot was analysed for kerogen type determination and presence of type II/III kerogen was identified. This study concludes that the source rock contains abundant humic organic matter that was deposited in a transitional (Fluvio-deltaic) to marginal marine environment under oxic conditions.

鱼粪化石特征对晚三叠世湖泊生态系统的启示——以鄂尔多斯盆地南部长7段为例

粪化石是一类重要的遗迹化石,其内含物常保存被捕食生物的残余及一些微生物、软组织甚至古DNA信息,对解读地质历史时期的湖泊生态信息有重要意义。鄂尔多斯盆地南部铜川地区三叠系延长组长7段下部页岩的鱼粪石,其为略扁平的纺锤形化石,尖而薄,表面有明显的螺旋纹。观察粪化石的内含物情况,发现其主要由未完全消化的动植物残体组成,包括鱼鳞、骨骼碎片,以及以含磷白云岩为生长基的大量矿物聚集体。鱼粪化石形成于开放型淡水湖泊中的半深湖—深湖区,大部分保存完好,属于典型的原地埋葬。该鱼粪的生物源为一种大型的、鱼肠内具有较多螺旋瓣的肉食性鱼类。晚三叠世湖泊中出现了复杂的多层营养系统,主要由生产者、消费者构成,食物链较为复杂。该研究成果表明经历二叠纪末生物大灭绝的晚三叠世多层级营养湖泊生态系统已经基本恢复。另外,微生物的参与及泥质含量较高的厌氧环境使得粪化石保存完好,可为恢复和重建晚三叠世卡尼期湖泊生态系统提供重要依据。

黔桂地区下石炭统富有机质页岩的页岩气勘探意义

一套总厚度接近300 m的富有机质页岩,总有机碳含量(TOC)普遍大于2%是其基本特征,主导着下石炭统杜内阶至维宪阶的鹿寨组,集中发育在黔桂地区所在的华南板块滇黔桂盆地的台间盆地相带之中的三级海平面上升期,代表着一套重要的潜在性页岩气勘探目的层。更为重要的是,特殊的形成发育时代,从深水台间盆地相的鹿寨组向浅水连陆台地中的深水陆棚相英塘组的相变和穿时减薄,而且结束于一套煤系地层主导的三角洲沉积体系的沉积过程之中;这些特征不但将这套富有机质页岩特征化,而且代表着一个与欧美地区泛大陆上的下石炭统(密西西比亚系)存在差异巨大的早石炭世沉积序列;因为在泛大陆上,只有石炭系的上部(上石炭统:宾夕法利亚亚系)储存着大量的煤,石炭系下部(下石炭统,或密西西比亚系)则包含着不同寻常的大套灰岩。这一套可以归为缺氧盆地相的下石炭统富有机质页岩,其中的有机质堆积作用,主要为以下3个因素之间复杂的相互作用所形成,即:①得到增强的生产率;②与还原条件相关而得到增强的有机质保存作用;③得到较低沉积作用速率导致的减弱的有机质稀释作用;而且这3个因素还直接受到海平面波动控制。但是,除了这3个因素之外,细粒植物碎屑的“生物碳泵(The biological carbon pump)”,也应该是这一套富有机质页岩中有机质富集的另外一个重要机制,尽管还存在许多细节问题需要进一步研究。

济阳坳陷古近系沙三下—沙四上亚段咸化湖盆证据及页岩油气地质意义

济阳坳陷是渤海湾盆地常规油气最为富集的坳陷之一,也是页岩油获得全面战略性勘探突破的坳陷,古近系沙河街组发育沙三下亚段、沙四上亚段2套主力烃源岩,其沉积环境颇受争议。利用页岩系统取芯井岩石学、元素地球化学、同位素和包裹体等资料对页岩沉积环境进行系统研究。结果表明:古近系沙三下—沙四上亚段页岩为气候控制下的咸化湖盆的产物,主要发育富碳酸盐纹层状岩相,碳酸盐矿物质量分数高,多呈纹层状、透镜状产出,平均质量分数为43%,背散射扫描电镜下部分页岩样品发现NaCl、BaSO_(4)和SrSO_(4)典型的咸化湖盆标志性矿物,页岩沉积期水体盐度相对较高;水体环境的w(Sr)/w(Ba)大于1,Sr元素质量分数大于500μg/g,B元素质量分数大于75×10^(-6),相当硼质量分数主要分布在300×10^(-6)~700×10^(-6),均显示为咸化环境;页岩w(^(87)Sr)/w(^(86)Sr)为0.710 7~0.712 4,明显高于同期海水的w(^(87)Sr)/w(^(86)Sr),结合对应稀土元素Ce正异常特征,认为沉积期水体条件受控于盆地自身环境,与海侵没有必然联系;碳酸盐矿物δ^(18)O主要分布在-11‰~-3‰,δ^(13)C主要分布在0~6‰,δ^(18)O、δ^(13)C均偏大,与沉积期湖盆气候相对干旱、湖水蒸发作用增强有关;页岩中检测到气液两相原生盐水包裹体均一化温度范围在32.5~45.3℃,对应盐度范围为19.21%~27.78%,成岩早期地层流体盐度较高;气候控制下的咸水环境为富碳酸盐页岩形成提供条件,奠定济阳坳陷古近系沙三下—沙四上亚段页岩油富集高产的基础。

济阳坳陷沙河街组富碳酸盐岩型页岩元素特征及其在岩相识别中应用研究

近年来济阳坳陷富碳酸盐岩型页岩油获得商业突破,针对该地区沙河街组页岩层系研究也逐渐受到学者的广泛关注(刘惠民,2022)。研究显示济阳坳陷页岩发育多种类型岩相,且纵向上变化快,具有较强非均质性(王勇等,2016),要实现岩相的连续刻画需要结合矿物分析、有机碳含量分析、沉积构造分析以及典型矿物结晶程度分析等多种实验手段(张顺等,2017).

富有机质泥页岩孔隙结构研究进展及展望

探究富有机质泥页岩孔隙结构的划分方案、前沿表征方法、演化及发育影响因素,对页岩油储量评价及商业开发具有指导意义。通过调研富有机质泥页岩孔隙结构研究进展,归纳孔隙的划分方案,对比不同现代测试手段在泥页岩孔隙结构表征过程中的优劣性,探讨海、陆相泥页岩孔隙结构的演化模式和有机、无机孔隙发育的主控因素,展望富有机质泥页岩孔隙研究未来的发展趋势。结果表明:(1)泥页岩储层表征的手段主要可以划分为成像法、流体侵入法、吸附法、散射法四类。(2)红外连用的原子力显微镜(AFM-IR)能够揭示泥页岩中显微组分的化学和岩石力学非均质性,小角中子散射(SANS)、核磁共振(NMR)和纳米CT技术是揭示孔隙连通性的重要途径。(3)沉积环境控制着泥页岩岩相和有机质母质来源,成岩和生烃作用及其相互间影响是泥页岩孔隙演化的主控因素,海、陆相泥页岩孔隙演化随时间和深度总体上均有“减孔→增孔→减孔→增孔→减孔”的规律,但陆相泥页岩在未熟-成熟阶段孔隙变化得更频繁。(4)Ⅰ型干酪根的有机质孔发育潜力远高于Ⅲ型干酪根,强生烃能力的腐泥组显微组分可发育丰富的有机孔隙,液态烃运移之后经二次裂解形成的焦沥青能提供更有效的连续性渗透路径。(5)成岩过程中无机矿物间的相互转化,长石、碳酸盐岩等矿物差异性溶蚀,压实、压溶和胶结作用等均会复杂化无机孔隙网络,有机-无机相互作用及矿物自身的岩石力学性质也是无机孔隙发育的重要影响因素。岩心在地表和地下所处环境差异巨大,未来的研究需要建立一个页岩孔隙在地面与地层条件下的反馈机制和矫正机制,进一步还原页岩油气在地下孔隙结构中真实的赋存状态。

松辽盆地北部青山口组富烃页岩形成环境与成因

通过古地温、古地貌、沉积环境定量恢复及地质事件综合研究,分析青山口组富烃页岩形成环境及成因。结果表明,松辽盆地青山口组富烃页岩R_(o)介于0.75%~1.60%,游离烃含量高,介于(4~12)mg/g,形成于古地温梯度(50~70)℃/km的高温热盆背景;在拉伸大地动力学及热沉降背景下形成了正断层密集断裂带控制的页岩层系,两凹一凸的古地貌为页岩形成演化提供富集场所;湖相温湿气候及岩浆热液为藻类繁殖成为厚层富烃页岩发育奠定物质基础;缺氧的半深湖—深湖还原—强还原环境有利于有机质埋藏。综合分析表明,构造、湖相沉积与古地温耦合作用奠定了富烃页岩的构造背景和热动力条件,温湿气候、缺氧环境及火山热液带来的营养物质是富烃页岩形成的重要原因。

来凤地区龙马溪组含气页岩测井识别——以WY1井为例

湖北龙马溪组海相页岩是除四川盆地外可能实现页岩气勘探突破点之一,测井技术是一种十分成熟的油气勘探开发研究手段,本文以来凤地区WY1井的测井为基础,对龙马溪组含气页岩层段测井响应特征进行系统研究。结果表明,WY1井龙马溪组含气页岩层段具有高自然伽马、高铀、高钍、高补偿中子、高声波时差及低密度的测井响应特征,深、浅侧向电阻率低于下伏宝塔组碳酸盐岩,高于砂质页岩,且正差异反映岩层中发育高角度裂缝的层段。通过测井曲线叠合以及交会图版分析发现,含气页岩层自然伽马—岩性密度测井叠合曲线及声波时差—岩性密度测井叠合曲线具有明显的正差异,而自然伽马—补偿中子和声波时差—补偿中子呈现明显的负差异,且声波时差—岩性密度叠合测井曲线对于含气层段的指示作用最为准确;声波时差—补偿中子测井交会图、补偿中子—自然伽马测井交会图以及深侧向电阻率—补偿中子测井交会图对于富有机质含气页岩的识别作用最明显。

富水地层炭质页岩隧道初期支护侵限处治技术

依托云南省勐绿高速公路金扬河隧道右线进口段,对富水地层炭质页岩隧道三台阶法施工中的初期支护侵限问题进行分析研究,从变形控制、径向注浆加固、支护加强、钢架拆换、开挖方法优化等方面,针对性地采取处治措施,结合围岩变形监测,成功解决初期支护侵限问题并确保了施工安全。

Shale Gas Formation and Occurrence in China： An Overview of the Current Status and Future Potential

Shale gas is one of the most promising unconventional resources both in China and abroad. It is known as a form of self-contained source-reservoir system with large and continuous dimensions. Through years of considerable exploration efforts, China has identified three large shale gas fields in the ruling, Changning and Weiyuan areas of the Sichuan Basin, and has announced more than 540 billion m3 of proven shale gas reserves in marine shale systems. The geological theories for shale gas development have progressed rapidly in China as well. For example, the new depositional patterns have been introduced for deciphering the paleogeography and sedimentary systems of the Wufeng shale and Longmaxi shale in the Sichuan Basin. The shale gas storage mechanism has been widely accepted as differing from conventional natural gas in that it is adsorbed on organic matter or a mineral surface or occurs as free gas trapped in pores and fractures of the shale. Significant advances in the techniques of microstructural characterization have provided new insights on how gas molecules are stored in micro- and nano-scale porous shales. Furthermore, newly-developed concepts and practices in the petroleum industry, such as hydraulic fracturing, microseismic monitoring and multiwell horizontal drilling, have made the production of this unevenly distributed but promising unconventional natural gas a reality. China has 10-36 trillion m3 of promising shale gas among the world＇s whole predicted technically recoverable reserves of 206.6 trillion m3. China is on the way to achieving its goal of an annual yield of 30-50 billion m3 by launching more trials within shale gas projects.

Sedimentary and geochemical characteristics of the Triassic Chang 7 Member shale in the Southeastern Ordos Basin,Central China

The Ordos Basin is the largest petroliferous basin in China, where the Chang 7 Member shale serves as the major source rock in the basin, with an area of more than 100,000 km^2 So far, sedimentary and geochemical characterizations have rarely been conducted on the shale in shallow(< 1000 m) areas in the southeastern part of the basin, but such characterizations can help identify the genesis of organic-rich shale and promote the prediction and recovery of shale oil. In this paper,several outcrop sections of the Chang 7 Member in the Tongchuan area were observed and sampled, and sedimentary and geochemical characterizations were conducted for the well-outcropped YSC section. The study results show that the Chang7 Member shale is widely distributed laterally with variable thickness. The organic-rich shale is 7-25 m thick in total and exhibits obvious horizontal variation in mineral composition. In the eastern sections, the shale contains organic matter of TypeⅡ_2-Ⅲ and is low in thermal maturity, with high clay mineral content, low K-feldspar content, and no pyrite. In the western sections, the shale contains Type Ⅱ_1 organic matter and is low in thermal maturity, with high clay mineral, K-feldspar, and pyrite contents. The YSC section reveals three obvious intervals in vertical mineral composition and organic abundance.The Chang 7 Member organic-rich shale(TOC > 10%) contains mainly sapropelite and liptinite, with Type Ⅱ kerogen. It is generally characterized by a hydrocarbon potential of more than 70 mg/g, low maturity, and shallow-semideep lacustrine facies. In the western sections, the shale, still in a low maturity stage, has a higher hydrocarbon potential and is optional for shale oil recovery. However, the Chang 7 Member shale in the study area is highly heterogeneous and its shale oil recovery is practical only in the organic-rich intervals.

Molecular Structure of Kerogen in the Longmaxi Shale: Insights from Solid State NMR, FT-IR, XRD and HRTEM

Kerogen plays an important role in shale gas adsorption,desorption and diffusion.Therefore,it is necessary to characterize the molecular structure of kerogen.In this study,four kerogen samples were isolated from the organic-rich shale of the Longmaxi Formation.Raman spectroscopy was used to determine the maturity of these kerogen samples.Highresolution transmission electron microscopy(HRTEM),13 C nuclear magnetic resonance(13 C NMR),X-ray diffraction(XRD)and Fourier transform infrared(FT-IR)spectroscopy were conducted to characterize the molecular structure of the shale samples.The results demonstrate that VReqv of these kerogen samples vary from 2.3%to 2.8%,suggesting that all the kerogen samples are in the dry gas window.The macromolecular carbon skeleton of the Longmaxi Formation kerogen is mainly aromatic(fa’=0.56).In addition,the aromatic structural units are mainly composed of naphthalene(23%),anthracene(23%)and phenanthrene(29%).However,the aliphatic structure of the kerogen macromolecules is relatively low(fal*+falH=0.08),which is presumed to be distributed in the form of methyl and short aliphatic chains at the edge of the aromatic units.The oxygen-containing functional groups in the macromolecules are mainly present in the form of carbonyl groups(fac=0.23)and hydroxyl groups or ether groups(falO=0.13).The crystallite structural parameters of kerogen,including the stacking height(Lc=22.84?),average lateral size(La=29.29?)and interlayer spacing(d002=3.43?),are close to the aromatic structural parameters of anthracite or overmature kerogen.High-resolution transmission electron microscopy reveals that the aromatic structure is well oriented,and more than 65%of the diffractive aromatic layers are concentrated in the main direction.Due to the continuous deep burial,the longer aliphatic chains and oxygen-containing functional groups in the kerogen are substantially depleted.However,the ductility and stacking degree of the aromatic structure increases during thermal evolution.This study provides quantitative information on the molecular structure of kerogen samples based on multiple research methods,which may contribute to an improved understanding of the organic pores in black shale.

Connotation and strategic role of in-situ conversion processing of shale oil underground in the onshore China

In-situ conversion processing (ICP) of shale oil underground at the depth ranging from 300 m to 3 000 m is a physical and chemical process caused by using horizontal drilling and electric heating technology, which converts heavy oil, bitumen and various organic matter into light oil and gas in a large scale, which can be called"underground refinery". ICP has several advantages as in CO2capture, recoverable resource potential and the quality of hydrocarbon output. Based on the geothermal evolution mechanism of organic materials established by Tissot et al., this study reveals that in the nonmarine organic-rich shale sequence, the amount of liquid hydrocarbon maintaining in the shale is as high as 25%in the liquid hydrocarbon window stage (R o less than 1.0%), and the unconverted organic materials (low mature-immature organic materials) in the shale interval can reach 40%to 100%. The conditions of organic-rich shale suitable for underground in-situ conversion of shale oil should be satisfied in the following aspects, TOC higher than 6%, R o ranging between 0.5%and 1%, concentrated thickness of organic-rich shale greater than 15 meters, burial depth less than 3 000 m, covering area bigger than 50 km2, good sealing condition in both up-and down-contacting sequences and water content smaller than 5%, etc. The shale oil resource in China’s onshore region is huge. It is estimated with this paper that the technical recoverable resource reaches 70-90 billion tons of oil and 60-65 trillion cubic meters of gas. The ICP of shale oil underground is believed to be a fairway to find big oil in the source kitchen in the near future. And it is also believed to be a milestone to keep China long-term stability of oil and gas sufficient supply by putting ICP of shale oil underground into real practice in the future.

Experimental Study of Partial Melting of Mantle Peridotite -A Discussion about the Genesis of Sih'ca-rich Fluids (Melts)

Experiments on partial melting of mantle lherzolite have been realized at 0.6 and 1.0 GPa and the chemical compositional variations of melts during different melting stages have been first discussed. The results show that the trends of variations in SiO2, CaO, Al2O3, Na2O and TiO2 are different at different melting stages. The melts produced at lower pressure are richer in SiO2 than those at higher pressure. The mantle-derived silica-rich fluids (silicate melts) are polygenetic, but the basic and intermediate-acid silicate melts in mantle peridotite xenoliths from the same host rocks, which have equivalent contents of volatile and alkali components and different contents of other components, should result from in-situ (low-degree) partial melting of mantle peridotite under different conditions (e.g. at different depths, with introduction of C-O-H fluids or in the presence of metasomatic minerals). The intermediate-acid melts may be the result of partial melting (at lower pressure) Opx + Sp + K-Na-rich fluid ±(Am-phi) ± (Phlog) = OI + melt. But the intermediate-acid magmas cannot be produced from the partial melting of normal mantle peridotite unless the crustal materials are introduced to some extent.

陆相富碳酸盐页岩结构特征与页岩油可动性——以济阳坳陷古近系沙河街组页岩为例

基于岩矿及地球化学分析、物性测定、镜下观测及不同薄层剥离测试等手段,剖析了渤海湾盆地济阳坳陷古近系沙河街组富碳酸盐页岩的结构特征,对比了不同类型页岩薄层的有机质丰度、储集性及含油性,划分出典型的页岩储-渗结构类型,并分析了不同类型页岩储-渗结构中油的可动性。取得以下认识:①泥质层与方解石层重复叠置是富碳酸盐页岩的主要结构类型,其中方解石层分为泥晶方解石层、粉晶方解石层和纤维状方解石脉。②泥质层是页岩有机质丰度及孔隙度的主要贡献者,具有最好的生烃能力、储集性能和含油性;而泥晶方解石层也具有较好的生烃潜力、储集性和含油性;粉晶方解石层和纤维状方解石脉具有较好的渗流输导性能。③济阳坳陷富碳酸盐页岩主要发育4种类型储-渗结构,各类储-渗结构中油的可动性强弱依次为:富粉晶方解石层页岩储-渗结构、富复合方解石层页岩储-渗结构、富纤维状方解石脉页岩储-渗结构、富泥晶方解石层页岩储-渗结构。济阳坳陷沙河街组页岩油在不同热演化阶段具有不同的储-渗结构类型勘探目标。

松辽盆地白垩系青山口组页岩层系非均质地质特征与页岩油甜点评价

松辽盆地白垩系青山口组湖相沉积发育规模富有机质页岩,古页油平1井实现了深湖区古龙页岩油勘探突破。为进一步精细评价湖盆不同相带页岩层系地质特征,明确陆相湖盆页岩油甜点特征,按青山口组页岩形成环境差异,开展湖盆不同相带页岩层系地质特征非均质性研究。淡水湖盆不同相带页岩层系存在富有机质(总有机碳含量TOC>3%)纹层状黏土(质)页岩、纹层状黏土(质)页岩、长英(质)页岩、纹层状介壳页岩、块状泥岩、灰岩和白云岩7种类型,分别评价生烃与滞留烃总量差异及烃类流动性、储集性、可压性和产油能力差异,据此提出页岩油资源甜点与工程甜点。根据TOC和S_(1)(热解烃含量)将青山口组页岩资源甜点划分为Ⅰ,Ⅱ和Ⅲ类,其中Ⅰ类资源甜点TOC大于3.0%,S_(1)大于4.0 mg/g;Ⅱ类资源甜点TOC在1.5%~3.0%,S_(1)在1.0~4.0 mg/g;Ⅲ类资源甜点TOC小于1.5%,S_(1)小于1.0 mg/g。半深湖-深湖相页岩多为Ⅰ类和Ⅱ类资源甜点,滨浅湖相页岩则以Ⅱ类和Ⅲ类资源甜点为主。通过不同相带岩相含油性、渗流性、可压性、源岩特性和物性等因素分析,优选松辽盆地青山口组页岩油主力靶体。