有机质含量对磷酸镁水泥固化土性质的影响研究

许多重要的软土工程譬如基坑、路基工程在破坏后需要快速修复,磷酸镁水泥的出现很好地满足了这一现代建设的要求,但不同地区软土的有机质含量不同,而有机质的含量对固化土的性质有着重要影响。为了研究磷酸镁水泥加固不同有机质含量软土的加固规律,本文通过向烘干后的软土中添加腐殖酸,人为制备不同有机质含量的土样,并取相同条件下PO水泥加固软土作对比,通过相关力学试验得到以下规律:两种水泥在加固不同含量有机质软土的过程中,加固效果都会随着有机质含量的升高而逐渐降低;磷酸镁水泥在快速修复和凝结方面明显优于PO水泥,但磷酸镁水泥中长期加固有机质软土的效果却不及PO水泥。同时利用SEM试验对得到的规律进行了解释并分析其微结构演化特征。该研究成果独到地分析了有机质含量变化对磷酸镁水泥加固效果的影响,证明了磷酸镁水泥可以应用于软土的抢修工程建设中,对加固软土工程具有指导和借鉴意义。     

Quantitative study on hydrocarbon expulsion mechanism based on micro-fracture

The significance of source rocks for oil and gas accumulation has been indisputably acknowledged. Moreover, it has been gradually realized that there is difference between hydrocarbon generation capacity and hydrocarbon expulsion capacity, and this has prompted research on hydrocarbon expulsion efficiency. However, these studies dominantly highlight the results of hydrocarbon expulsion, and investigation into the corresponding process and mechanism is primarily from a macroscopic perspective. Despite its wide acceptance as the most direct hydrocarbon expulsion mode, hydrocarbon expulsion through micro-fractures is still not sufficiently understood. Therefore, this study obtains observations and performs experiments on two types of source rocks (mudstones and shales) of the Chang 7 oil group of the Yanchang Formation in Ordos Basin, China. Microscopy reveals that organic matter is non-uniformly distributed in both types of source rocks. Specifically, mudstones are characterized by a cluster-like organic matter distribution, whereas shales are characterized by a layered organic matter distribution. Thermal evolution simulation experiments demonstrate that the hydrocarbon generation process is accompanied by the emergence of micro-fractures, which are favorable for hydrocarbon expulsion. Moreover, based on the theories of rock physics and fracture mechanics, this study establishes micro-fracture development models for both types of source rocks, associated with the calculation of the fracture pressure that is needed for the initiation of fracture development. Furthermore, the relationship between the fluid pressure, fracture pressure, and micro-fracture expansion length during micro-fracture development is quantitatively explored, which helps identify the micro-fracture expansion length. The results indicate that the development of micro-fractures is commonly impacted by the morphology and distribution pattern of the organic matter as well as the mechanical properties of the source rocks. The micro-fractures in turn further affect the hydrocarbon expulsion capacity of the source rocks. The results of this study are expected to provide theoretical and practical guidance for the exploration and exploitation of tight oil and shale oil.     

Influence of Bedding and Mineral Composition on Mechanical Properties and Its Implication for Hydraulic Fracturing of Shale Oil Reservoirs

The premise of hydraulic fracturing is to have an accurate and detailed understanding of the rock mechanical properties and fracture propagation law of shale reservoirs. In this paper, a comprehensive evaluation of the mechanical properties of the shale oil reservoir in the south of Songliao Basin is carried out. Based on the experiments and the in-situ stress analysis, the fracture propagation law of three types of shale reservoirs is obtained, and the suggestions for fracturing are put forward. The results have shown that the fracture propagation of pure shale and low mature reservoir is easy to open along the bedding plane under compression loading, which is greatly influenced by the bedding. Sand-bearing shale is slightly better, the fractures of which are not easy to open along the bedding plane. The mechanical experimental results show that all the samples have the characteristics of low compressive strength, low Young''s modulus and strong anisotropy, indicating that the shale oil reservoir is certain plastic, which is related to its high clay mineral content and controlled by the bedding development. Compared with pure shale and low mature shale, the sand-bearing shale has less clay content and less developed bedding, which maybe the main reason for its slightly better brittleness. Overall, the expansion of hydraulic fracture is controlled by in-situ stress and bedding. Because of the development of bedding, it is easy to form horizontal fractures. Thus it is not suitable for horizontal well fracturing. Because of the high content of clay minerals, the applicability of conventional slick hydraulic fracturing fluid is poor. It is suggested to use vertical well or directional well to carry out volume fracturing. In this way, the effect of bedding can be effectively used to open and connect the bedding and form a larger fracture network.     

中子活化分析铂族元素的干扰反应问题

探讨了中子活化分析铂族元素的一些干扰反应，如Ａｕ对Ｐｔ的干扰，Ｕ对Ｒｕ和Ｐｄ的干扰，并就Ａｕ对Ｐｔ的干扰程度进行了详细的计算。在照射时间为１ｄ，中子注量率为１×１０１３ｎ·ｃｍ－２·ｓ－１的条件下进行计算，对于ｍＰｔ／ｍＡｕ＝１的样品，Ａｕ对Ｐｔ的干扰达７５％；ｍＰｔ／ｍＡｕ＝１０时，干扰达２３％；ｍＰｔ／ｍＡｕ＝２０，干扰为１３％，ｍＰｔ／ｍＡｕ＝３０，干扰降低为９％。这表明对于多数岩石样品Ａｕ干扰Ｐｔ相当严重，在采用中子活化法测定地质试样中Ｐｔ时必须对Ａｕ进行预分离。此外还就Ｕ对Ｒｕ和Ｐｄ的干扰情况进行了讨论，指出对于大多数超镁铁岩和硫化物矿石其干扰可以忽略或只需进行较小的校正，但对于基性岩和酸性岩就必须进行校正     

金矿床密集区形成的基本条件—以华北地台为例

金矿床密集区受含金丰度高的岩石圈地幔区控制和制约。本文以华北地台若干金矿床密集区为例,从地壳演化的角度,初步探索了初始地壳的含金丰度变化与金矿床密集区的关系。文章认为,初始地壳只有经活化改造和活化再造,才能形成金元素的富集域或金矿床密集区。金矿床密集区的形成是矿源、热源、搬运介质和构造条件的统一体。其中,前寒武纪古老变质基底是金矿形成的物质基础,变质基底双层结构的下层结构是金矿床的主要赋存部位,岩浆一热构造作用是初始地壳内成矿物质活化的动力,岩浆活动、流体运移是矿质的搬运工具,构造断裂是含矿热液运移的通道和聚集的空间,特别是深断裂能使深源成矿物质迁移至地壳,使矿质来源更加丰富。     

中国北东部铀矿化与大地构造活动及演化的关系

笔者认为,中国北东部地区处于欧亚东西向海西期铀-多金属成矿带与环太平洋成矿带相交的部位,区内铀矿化产于前寒武纪基底褶皱阶段、古生代地槽褶皱阶段、反射活化阶段和地洼阶段,具有铀成矿作用时间长、矿化类型多的特点,4大工业类型的铀矿床都有产出。该区中新生代岩浆岩、特别是火山岩十分发育,地洼期铀成矿作用以热液型为主,特别是与火山作用有关的铀成矿作用具有十分重要的意义。     

腾冲地洼区—一个复合型地洼区

腾冲地区是由元古代的地槽褶皱带,经古生代—三叠纪的地台体制,至侏罗纪开始构造-岩浆活化作用形成的地洼区。该区地洼阶段的演化及成因机制分为二个阶段。早期(侏罗纪-早第三纪)以花岗岩多次侵入为特征。这些花岗岩的主元素、微量元素及同位素特征均可与中国东部地洼花岗岩相对比。此阶段的地台活化作用源自该区的深部活动过程。晚第三世纪开始,该区的大地构造演化机制发生重大转折。巽他陆块与印度陆地的碰撞控制着该区的活化作用,形成广泛的中—基性火山岩喷发,这些火山岩的地球化学研究证明其构造背最及成因均与火山弧岩石相似。因此,从成因机制角度,腾冲地区属一个复合型地洼区。     

Microstructure characterization of mechanically activated hematite using XRD line broadening

The effect of dry milling in a vibratory mill on the structural changes and microstructural characteristics of hematite using different methods was investigated. We have described the line profile analysis (LPA) to extract the size of coherently diffracting domains and the lattice strain of activated hematite in a vibratory mill. The Warren–Averbach and Williamson–Hall methods were used as the main tools for characterization. The changes in the particle size, surface area and new phase formation of hematite concentrate were also investigated. It was concluded that the breakage and agglomeration of particles take place mainly at lower and higher levels of specific energy input, respectively. The pores in agglomerates remain accessible for the nitrogen gas. Milling of hematite increased specific surface area up to 18.4 m²/g. The hematite milled under various levels of specific energy input did not undergo a significant reaction or phase transformation during milling. The Williamson–Hall method confirms its merit for a rapid overview of the line broadening effects and possible understanding of the main causes. The anisotropic character of line broadening for deformed hematite as a function of specific energy input was revealed. Higher level of specific energy input favors the generation of small crystallite size, higher microstrain, BET surface area, amorphization and line breadth. The Warren–Averbach method suggested that the nanocrystalline hematite with grain sizes of 73.5–12.2 nm was formed by mechanical treatment using different milling intensities in the vibratory mill. The root mean square strain (RMSS) at L = 10 nm varies between 1.7 × 10^− 3 and 4.0 × 10^− 3 depending on the level of energy input. Limits in the applicability of Williamson–Hall method and reliability of the results are discussed in detail.     

大洋海底扩张图蛛网裂缝的扁壳力学模式

在考虑半径为10~3公里数量级的全球海洋岩石圈时,必须考虑地球的弯曲效应,当作弹性地基上的薄扁球壳。若忽略曲率,将产生各向异性和不均匀性。本文还考虑了地热对岩石圈的作用,得出洋底蛛网状裂缝的力学表达式。