The Influence of Extractable Organic Matter on Pore Development in the Late Triassic Chang 7 Lacustrine Shales, Yanchang Formation, Ordos Basin, China

To investigate the influence of extractable organic matter （EOM） on pore evolution of lacustrine shales, Soxhlet extraction, using dichloromethane, was performed on a series of Chang 7 shale samples （Ordos Basin, China） with vitrinite reflectance of 0.64% to 1.34%. Low-pressure gas adsorption experiments were conducted on the samples before and after extraction. The pore structure parameters were calculated from the gas adsorption data. The results show complex changes to the pore volumes and surface areas after extraction. The pore development of both the initial and extracted samples is strongly controlled by total organic carbon （TOC） content. Micropores developed mainly in organic matter （OM）, while mesopores and macropores predominantly developed in fractions other than OM. The influence of EOM on micropores is stronger than on mesopores and macropores. Organic solvents with a higher boiling point should be used to explore the effect of EOM on pore structure in the future.

Application of Pore Evolution and Fracture Development Coupled Models in the Prediction of Reservoir "Sweet Spots" in Tight Sandstones

The Chang-63 reservoir in the Huaqing area has widely developed tight sandstone ＂thick sand layers, but not reservoirs characterized by rich in oil＂, and it is thus necessary to further study its oil and gas enrichment law. This study builds porosity and fracture development and evolution models in different deposition environments, through core observation, casting thin section, SEM, porosity and permeability analysis, burial history analysis, and ＂four-property-relationships＂ analysis.

学生数学符号意识PORE评价框架的构建

“符号意识”作为《义务教育数学课程标准（2011年版）》提出的10个核心素养之一，是学生必须具备的一种数学素养．评价学生符号意识的发展水平，是教育工作者在义务教育阶段数学课程与教学中不能回避的任务．基于对符号意识内涵的分析和国内外的相关研究成果的借鉴，构建了一个关于数学符号意识4个维度（数学符号的感知，数学符号的运算，数学符号的推理，数学符号的表达），每个维度包括由低到高3或4个水平的PORE评价框架．

下扬子地区大隆组页岩孔隙发育特征及主控因素

为了研究下扬子地区二叠系大隆组页岩孔隙结构特征,联合扫描电镜、高压压汞、N_(2)/CO_(2)气体吸附实验手段对页岩储层孔隙结构进行了研究。结果表明,研究区二叠系大隆组页岩孔隙类型以有机质孔、粒间孔、粒内孔、溶蚀孔和微裂缝为主;孔隙结构为多峰态-多尺度孔隙并存,微孔-介孔-宏孔都有发育,各个尺度的孔隙对孔容都有所贡献,其中以0.75~1.5 nm的微孔、10~35 nm的介孔及大于100 nm的宏孔为主。通过拟合孔体积、比表面积与埋深、有机碳(TOC)、成熟度(R_(O))以及矿物含量的相关性发现,微孔表面积与埋深、TOC呈正相关;微介孔体积和表面积均与R_(O)呈负相关;宏孔体积与埋深、TOC、黏土矿物含量呈负相关,与R_(O)呈较正相关;宏孔表面积与埋深成正比,与R_(O)成反比。研究结果说明下扬子地区大隆组页岩孔隙发育主要受控于埋深、TOC、R_(O)、黏土矿物含量等因素。

原生煤体多级孔隙团簇发育特征及其CT图像识别

为了以微观尺度研究原生煤体瓦斯赋存空间结构特征,基于压汞测试、低温N2吸脱附实验和X-ray CT扫描技术的综合运用,对原生结构气煤和焦煤多级孔隙团簇发育特征进行了定量分析和图像识别,揭示了不同变质程度煤中多级孔隙团簇的发育特征。结果表明:SQY焦煤渗流孔较少、吸附孔丰富,而XG气煤渗流孔分布广泛,吸附孔孔径缺陷小,多级孔隙团簇发育均衡是瓦斯大量赋存、高效渗流的结构基础;大量发育的XG气煤渗流孔隙团簇和SQY焦煤吸附孔隙团簇空间结构复杂,体积优势是重要诱因;X-ray CT扫描技术能精确识别煤孔隙发育形貌特征;XG气煤矿物分布没有增强多级孔隙团簇空间非均质性;SQY焦煤大量发育的矿物占据了基质空间,是导致多级孔隙团簇发育差、非均质性强的内在因素。

Numerical Analyses of Caisson Breakwaters on Soft Foundations Under Wave Cyclic Loading

A caisson breakwater is built on soft foundations after replacing the upper soft layer with sand. This paper presents a dynamic finite element method to investigate the strength degradation and associated pore pressure development of the intercalated soft layer under wave cyclic loading. By combining the undrained shear strength with the empirical formula of overconsolidation clay produced by unloading and the development model of pore pressure, the dynamic degradation law that describes the undrained shear strength as a function of cycle number and stress level is derived. Based on the proposed dynamic degradation law and M-C yield criterion, a dynamic finite element method is numerically implemented to predict changes in undrained shear strength of the intercalated soft layer by using the general-purpose FEM software ABAQUS, and the accuracy of the method is verified. The effects of cycle number and amplitude of the wave force on the degradation of the undrained shear strength of the intercalated soft layer and the associated excess pore pressure response are investigated by analyzing an overall distribution and three typical sections underneath the breakwater. By comparing the undrained shear strength distributions obtained by the static method and the quasi-static method with the undrained shear strength distributions obtained by the dynamic finite element method in the three typical sections, the superiority of the dynamic finite element method in predicting changes in undrained shear strength is demonstrated.

湘西地区寒武系牛蹄塘组页岩孔隙发育特征及影响因素

湘西地区寒武系牛蹄塘组页岩具有厚度大、埋藏适中、有机质丰度高及热演化程度高等特点,具有较大的页岩气勘探开发潜力,为此,以牛蹄塘组富有机质页岩为研究对象,通过X射线衍射分析划分页岩岩相,利用场发射扫描电镜、CO_(2)及N_(2)吸附并结合分形特征对不同岩相页岩孔隙发育特征及其影响因素进行研究。研究结果表明:牛蹄塘组页岩孔隙类型主要包括有机孔、无机孔和微裂缝,岩相可分为硅质页岩、钙质页岩、混合硅质页岩和含泥硅质页岩,其中硅质页岩的有机孔最发育;页岩中的孔隙体积以介孔体积为主,比表面积主要以微孔表面积为主,不同岩相页岩的孔径分布特征相似,但硅质页岩的孔隙体积和比表面积显著比钙质页岩、混合硅质页岩和含泥硅质页岩的高,孔隙体系非均质性也更强;受有机碳质量分数和矿物组成的影响,牛蹄塘组页岩的孔隙结构出现明显差异,有机碳质量分数是控制孔隙发育的主要因素,石英对微孔发育有一定贡献,而黏土矿物与介孔的发育有关,但整体上矿物组成对孔隙发育影响较小;在湘西地区牛蹄塘组4种页岩岩相中,牛一段和牛二段底部的硅质页岩有机碳质量分数最高,有机孔较发育,孔隙体积和比表面积均显著比其他3种岩相页岩的高,可作为页岩气勘探的目的层段。

四川盆地二叠系龙潭组页岩孔隙发育特征及主控因素

为明确四川盆地二叠系龙潭组(吴家坪组)沉积期不同沉积相带页岩孔隙结构特征及发育主控因素,以綦江地区DYS1井岩心及利川地区沙溪剖面露头样品为研究对象,综合运用氩离子抛光扫描电镜、低温液氮—压汞联合测试、氮气吸附及聚焦离子束三维扫描(3D-FIB-SEM)等试验分析,对页岩孔隙发育程度和形态结构进行定量表征。研究表明:①处于潮坪潟湖相的DYS1井龙潭组页岩气层主要发育煤及与之相邻的暗色泥页岩,孔隙类型主要发育平行板状、夹板状微裂缝和黏土矿物孔,见有机质结构孔,但相对不太发育,孔径多小于50 nm,分布为多峰型,孔隙连通性中等。②处于深水陆棚相的利川沙溪剖面吴家坪组以暗色页岩为主,孔隙类型则以墨水瓶状沥青质有机孔为主,孔径多小于50 nm,分布为单峰型,孔隙连通性相对较好。③明确了有机质类型、TOC含量、矿物成分是影响龙潭组、吴家坪组孔隙发育的主控因素,其中深水陆棚相发育Ⅱ1型干酪根类型的页岩,TOC、硅质矿物含量与孔体积存在较好的正相关性,有机质孔更发育,潮坪—潟湖相发育Ⅲ型干酪根类型的煤和页岩,黏土矿物含量和TOC呈正向关耦合关系,与孔体积呈较好正相关性,其中黏土矿物影响更大,有机质孔相对占比小。

页岩纳米孔隙研究新进展

随着页岩油气勘探的兴起及近年来北美地区页岩油气开发取得的巨大成功,含气页岩储层的孔隙研究受到越来越多的重视。页岩储层不同于常规储层,其以纳米孔隙为主,无法用常规储层孔隙研究方法进行表征和评价。对目前国内外含气页岩孔隙分类及孔隙表征方法进行了综述,从定性及定量的角度对表征方法进行归类和总结,指出了各类方法的优缺点及应用范围。定性表征方法主要是利用聚焦离子束扫描电子显微镜、高分辨率的场发射扫描电子显微镜、透射电子显微镜、宽离子束扫描电子显微镜、原子力显微镜等电子显微成像分析技术及Nano-CT技术等直观描述页岩孔隙的几何形态、连通性和充填情况等;定量表征方法是利用气体吸附法、压汞实验、小角散射及核磁共振等技术定量分析页岩孔径大小及分布、比表面积等。进一步探讨了含气页岩纳米孔隙发育演化的控制因素以及纳米孔隙对页岩气聚集的影响。展望未来,在页岩纳米孔隙结构表征技术方面,应不断提高实验精度和效率,定性与定量表征相结合,改进三维成像技术;在页岩纳米孔隙储层评价研究方面,纳米孔隙发育演化的控制因素、纳米孔隙储层的储气及产气能力、陆相非均质页岩纳米孔隙的表征与评价是关注的重点领域。