Composite Sand Bodies Architecture of Deep-Water Turbidite Channels in the Niger Delta Basin

Deep-water turbidite channels have attracted much attention as a focused issue in petroleum exploration and development. Extensive studies have been performed on the architecture of turbidite channels, and most researches have focused on their geometric shapes, sedimentary processes and controlling factors. However, little attention has been paid to the distribution patterns, distribution laws and quantitative studies of composite sand bodies of turbidite channels. Taken one slope area of the Niger Delta Basin as an example, this study conducted a semi-quantitative to quantitative analysis on architecture of composite sand bodies of turbidite channels based on cores, well logging and seismic surveys. It is shown that turbidite channel systems can be classified as confined and unconfined channel systems. For confined channel systems, the vertical evolution process involves four stages. The sinuosity of a channel system is controlled by slope, with a negative power function relationship between them. When slope gradient reaches four degrees, the channel system is nearly straight. Based on the migration direction and migration amount of single channels within channel complexes, channel composite patterns can be divided into four classes（the lateral composite, en-echelon composite, swing composite and vertical composite） and several subclasses. Various channel composite patterns show specific distribution laws spatially. For meandering channel complexes at the middle-late evolution stage of confined channel systems, the lateral migration amongst single channels shows the features of integrity and succession. The sinuosity of single channels in the late period is greater than that in the early period, and cut-offs may occur locally when the sinuosity is larger than five degrees. This study provides a better understanding for the geological theory of deep-water sedimentary, and also improves exploitation benefits of this type of reservoirs.

Failure Envelopes of Wide-Shallow Composite Bucket Foundation for Offshore Wind Turbines in Silty Sand

The wide-shallow composite bucket foundation(WSCBF) is a new type of offshore wind power foundation that can be built on land and rapidly installed offshore, there by effectively reducing the construction time and costs of offshore wind power foundation. In this study, the horizontal bearing capacity is calculated by finite element simulation and compared with test results to verify the validity of results. In this process, the vertical load and bending load are respectively calculated by the finite element simulation. Under the vertical load effect, the bucket foundation and the soil inside are regarded as a whole, and the corresponding buckling failure mode is obtained. The ultimate vertical bearing capacity is calculated using empirical and theoretical formulas; the theoretical formula is also revised by finite element results. Under bending load, the rotational center of the composite bucket foundation(in a region close to the bucket bottom) gradually moves from the left of the central axis(reverse to loading direction) to the nearby compartment boards along the loading direction. The H–M envelope line shows a linear relationship, and it is determined that the vertical and bending ultimate bearing capacities can be improved by an appropriate vertical load.

Coating process of multi-material composite sand mold 3D printing

Sand mold 3 D printing technology is an advanced manufacturing technology which has great flexible manufacturing ability. A multi-material composite sand mold can control the temperature field of metallic parts during the pouring process, while the current sand mold 3 D printing technology can only fabricate a single material sand mold. The casting temperature field can not be adjusted by using single sand mold material with isotropous heat exchange ability during the pouring process. In this work, a kind of novel coating device was designed. Multi-material composite sand molds could be manufactured using the coating device according to the casting process demands of the final parts. The influences of curing agent content, coating velocity and scraper shape on compactness and surface roughness of the sand layer(silica sand and zircon sand) were studied. The shapes and sizes of transition intervals of two kinds of sand granules were also tested. The results show that, with the increase of the added volume of curing agent, the compactness of sand layer reduces and the surface roughness value rises. With the increase of the velocity of the coating device, the compactness of sand layer reduces and the surface roughness value rises similarly. In addition, the scraper with a dip angle of 72 degrees could increase the compactness value of the sand layer. The criteria of quality parmeters of the coating procedure are obtained. That is, the surface roughness(δ) of sand layer should be equal to or lesser than half of main size of the sand particles(Dm). The parameter H of the coating device which is the distance between the base of hopper and the surface of sand layer impacts the size of transition zone. The width of the transition zone is in direct proportion to the parameter H, qualitatively. Through the optimization of the coating device, high quality of multi-material sand layers can be obtained. This will provide a solution in manufacturing the multi-material composite sand mold.

Glass matrix composite material prepared with waste foundry sand

The technology of glass matrix of the composite material manufactured through a sintering process and using waste foundry sand and waste glass as the main raw materials was studied. The effects of technological factors on the performance of this material were studied. The results showed that this composite material is formed with glass as matrix, core particulate as strengthening material, it has the performance of glass and ceramics, and could be used to substitute for stone.

Long-term Properties of Aeolian Sand-magnesium Oxychloride Cement Composites and Its Engineering Application

In order to prepare a new material with long-term stable performance,low cost,easy construction,and ecological environmental protection,the influence of aeolian sand on the compressive and flexural strength as well as micro morphology and phase composition of magnesium oxychloride cement(MOC)was studied.The experimental results indicate that,with the increase of content of doping sand,the compressive strength and flexural strength of MOC decrease significantly.However,when the quality ratio of aeolian sand and light burned magnesia powder is 1:8,the performance meets the actual engineering needs.Namely,the compressive strength of MOC is not less than 18 MPa,and flexural strength is not less than 4 MPa.Meanwhile,within 12 months of age,the compressive strength and flexural strength are stable.There is no obvious change in phase composition,and its main phase is still 5·1·8 phase.Microscopic appearance changes from needle-like to gel-like shape.Based on engineering applications,it is found that when the novel sand-fixing material is used in the field for one year,its macroscopic feature is not damaged,compressive strength and flexural strength are also more stable,phase composition negligibly changes,and micro morphology has also been turned into be gellike shape.These further confirm the long-term stability and weather resistance of MOC doping aeolian sand,providing theoretical and technical support for the widely application of MOC in the field of sand fixation in the future.

Energy Consumption and Erosion Mechanism of Polyester Fiber Reinforced Cement Composite in Wind-blown Sand Environments

Considering the economic and environmental benefits associated with the recycling of polyester(PET)fibres,it is vital to study the application of fibre-reinforced cement composites.According to the characteristics of the wind-blown sand environment in Inner Mongolia,the erosion resistance of the polyester fibre-reinforced cement composites(PETFRCC)with different PET fibre contents to various erosion angles,velocities and sand particle flows was investigated by the gas-blast method.Based on the actual conditions of sandstorms in Inner Mongolia,the sand erosion parameters required for testing were calculated by the similarity theory.The elastic-plastic model and rigid plastic model of PETFRCC and cement mortar were established,and the energy consumption mechanism of the model under particle impact was analyzed.The experimental results indicate that the microstructure of PETFRCC rafter hydration causes a spring-like buffering effect,and the deformation of PETFRCC under the same impact load is slightly smaller than that of cement mortar,and the damage mechanism of PETFRCC is mainly characterized by fiber deformation and slight brittle spalling of matrix.And under the most unfavorable conditions of the erosion,the erosion rate of 0.5PETFRCC is about 57.69%lower than that of cement mortar,showing better erosion resistance.

The Development and Characterization of Zirconia-Silica Sand Nanoparticles Composites

The present study aims to develop zirconia-Silica sand nanoparticles composites through powder processing route and to study the physical properties, mechanical properties and microstructure of the composites. Zirconia based silica sand nanoparticles composite with 5, 10, 15 and 20 wt.% were developed through powder processing technique and sintered at 1500 ℃ for two hours. A decreasing trend of green density however an improvement in sintered density was observed. Also the addition of silica sand nanoparticles with 20 wt.% increased the hardness up to 12.45 GPa and microstructures indicated the diffusion mechanism of silica sand nanoparticles into pore sites of the composites.

Structures and Properties of Iron Matrix Composites with Tungsten Carbide Particle by EPC-V Process

In this paper the Expendable Pattern Casting with dry sand Vacuum(EPC-V) process is used to manufacture iron matrix composites with tungsten carbide particle.Microstructures of the composites layers were analyzed.The abrasive wear resistance of the composites layers were tested and compared with that of high chromium cast iron.The results show that the iron matrix composites with tungsten carbide particle have high hardness.The abrasive wear resistance of composites with tungsten carbide particle is higher than that of high chromium cast iron.The properties of the matrix materials have been improved remarkably.

Influence of UVB-Irradiation on the Structures and Solid Particle Erosion Resistance for CF/PC Composites

The service life and properties of Carbon fiber reinforced polycarbonate (CF/PC) composites are seriously affected by ultraviolet radiation from outdoor exposure during aging. In this work, the changes of structure and solid particle erosion resistance for CF/PC composites after ultraviolet irradiation were studied. It was shown that ultraviolet irradiation causes photo-oxygen aging and photo-fries re-arrangement of the composite, and the result was confirmed by FTIR. We correlated the solid particle erosion resistance with aging time, and found that the solid particle erosion resistance of CF/PC composites greatly decreased by UVB irradiation during 15 hours. Furthermore, the eroded material surface was analyzed using scanning electron microscope (SEM). It suggests that ultraviolet aging leads to plasticization and degradation, resulting in reduction of erosion resistance of the composite.

Bulk and molecular composition variations of gold-tube pyrolysates from severely biodegraded Athabasca bitumen

Gold-tube pyrolysis experiments were performed on two Athabasca oil sand bitumens at 300℃to 525℃with 2℃/h rate and 25℃step under 50 MPa.Pyrolysis temperature of 425℃is critical for weight loss of bulk bitumen and hydrocarbon generation and destruction.Polar compounds are the main source of saturated and aromatic hydrocarbon,gas and coke fractions.Molecular compositions in pyrolyzates vary systematically with increasing pyrolysis temperatures.High molecular weight n-alkanes(C26^+) are gradually destructed during pyrolysis due to thermal cracking.Moderate molecular weight n-alkanes(C21-C25)show the highest thermal stability in designed pyrolysis temperatures.The loss of low molecular weight n-alkanes(C20^-)might be caused by volatilization during pyrolysis,which may alter commonly used molecular parameters such as∑n-C20^-/∑n-C21^+,Pr/n-C17 and Ph/n-C18.Aromatic hydrocarbons were generated from 300 to 425℃,then condensation and dealkylation have been initiated at 425℃as evidenced by decreased summed alkylnaphthalenes to alkylphenanthrenes ratios and increased unsubstituted aromatics to substituted homologs ratios in higher temperatures.The occurrence of anthracene and benz[a]anthracene in pyrolysates indicates pyrogenic origin,while fluoranthene shows unexpected behaviors during pyrolysis.Ratios derived from them are not always reliable for pyrogenic source input diagnosis in environmental samples.

Sand Liquefaction Phenomena During the Seismic Crisis of May 2012 in Emilia,Northern Italy

In May 2012,the Emilia region of the Po Valley was struck by a seismic crisis with two major events of magnitude M_w 6.1and M_w 5.9.The first event induced widespread sand blows formed along buried channels and old crevasse splay deposits.In the days immediately following the events,the detailed mapping and sampling of the erupted sand was fundamental to record all the seismically-induced phenomena.The study of a trench dug across large fractures at San Carlo(Ferrara)provided also valuable information on the sand blows mechanism and regome.The sedimentological and compositional characteristics of the fracture-filling materials indicate that the sands were erupted from a layer located between 6.8 and 7.5 m depth.Older and deeper Holocene and Pleistocene sand layers were not apparently involved in the liquefaction phenomena.

A New Type of Exposed Oil Sand Mine

With several means of analysis, the unique organic compound component and distribution of exposed oil sand existing in Qinghai, north-west China, is revealed. Qinghhai oil sand has great content of light components with high saturated hydrocarbon content up to approximately 50%, while its heavy components of colloid and asphaltene is rather low (<38%); straight-chain alkane has a regular distribution concentrating mainly around C28; it has a very high atom ratio of H/C. The physical parameters of the oil sand mine are within the range of common heavy oils. Such chemical composition and distribution obviously differs from that of other known exposed oil sand mines. This particular property of the oil sand is formed due to the unique geographical and geological environment. Therefore, it is intended to exploit the mine with a new combined method, i.e., first drill horizontal wells and then opencut.

Gas evolution characteristics of three kinds of no-bake resin-bonded sands for foundry in production

No-bake resin-bonded sand is commonly used in casting production.However,its air pollution is relatively serious,especially in the molding and pouring process.For this reason,it is necessary to study the gas evolution characteristics of no-bake resin-bonded sand from room temperature to high temperatures,and not only the amount of gaseous products,but also the composition of the gaseous products.No-bake furan resin-bonded sand(#1),phenolic urethane no-bake resin-bonded sand(#2),and alkaline phenolic no-bake resin-bonded sand(#3)are the three most common no-bake resin-bonded sands in casting.The gas evolution volume and rate of these three no-bake resin-bonded sands were studied.Thermogravimetry-mass spectrometer(TG-MS),headspace-gas chromatography/mass spectrometer(HS-GC/MS),and pyrolysis-gas chromatography/mass spectrometer(PY-GC/MS)were used to measure the composition of the gaseous products emitted from binders at room temperature and high temperatures.The differences between formaldehyde,heterocyclic aromatic compounds(HAC),monocyclic aromatic hydrocarbons(MAH),and polycyclic aromatic hydrocarbons(PAHs)gaseous products from the three types of no-bake resin-bonded sands during the molding and casting process were compared.From the perspective of environmental protection,alkaline phenolic no-bake resin-bonded sand and no-bake furan resin-bonded sand are better than phenolic urethane no-bake resin-bonded sand.

砂颗粒矿物成分对MICP过程的影响及机理

微生物诱导碳酸钙沉淀(MICP)是一种绿色环保的新型土体加固技术,具有广泛的应用前景。为了研究砂颗粒矿物成分对MICP过程的影响,分别选用石英砂和钙质砂为代表性研究对象,利用环氧树脂胶结固化后打磨制成样片,再在配置好的菌液和胶结液中对样片表面进行MICP处理,结合X射线衍射(XRD)、扫描电镜(SEM)以及超声震荡试验定量分析了碳酸钙产量、矿物晶型、晶貌及界面胶结特性。结果表明:(1)钙质砂颗粒比石英砂颗粒更利于微生物诱导生成碳酸钙,平均单位面积碳酸钙生成量前者约为后者的5倍;(2)两种砂颗粒表面生成的碳酸钙主要为球霰石和方解石,钙质砂界面能更低,诱导生成更多的方解石;(3)石英砂表面生成的碳酸钙主要为较大的球形颗粒,而钙质砂表面的碳酸钙形貌主要为板片状;(4)微生物在钙质砂颗粒上诱导生成的碳酸钙呈现更高的界面胶结强度,经超声波震荡后,石英砂颗粒上碳酸钙的质量损失率约为钙质砂的10倍。在此基础上,运用微生物学、晶体化学、结晶矿物学等其他相关学科的理论,系统分析了石英砂和钙质砂对MICP过程及效果的影响机理,取得了新的认识,对优化MICP技术在岩土工程中的应用有重要意义。

上砂下黏地层中桩-筒复合基础V-H承载特性

海上风机基础不仅受自重等竖向力V作用,也因水流、波浪和风等影响而承受水平荷载H。为探讨上砂下黏地层中一种由单桩和吸力筒组成的新型海上风机桩-筒复合基础受V-H组合作用时的承载特性,自主设计完成了一系列室内桩-筒复合基础V-H组合加载模型试验,获得不同组合参数下桩-筒复合基础的荷载-位移曲线和桩身弯矩分布曲线,并绘制出V-H承载力包络线。在此基础上,采用ABAQUS建立了上砂下黏地层中桩-筒复合基础三维数值分析模型,经模型验证与参数分析,进一步讨论了砂土厚度、筒径、筒高以及加载高度等参数对桩-筒复合基础承载特性的影响曲线,并拟合出桩-筒复合基础承载力简化计算公式,分析结果表明:桩-筒复合基础能显著提高桩身水平承载力,增幅达30%~90%,且增加筒径比增加筒高更有利于提高基础水平承载力;上部砂土层较厚时,桩-筒复合基础存在一个使复合基础水平承载力达到最大的预加竖向荷载最佳值,其值随不同载荷工况在(0.4~0.7)Vult范围内变化。

不同改性方法对生物砂滤池生物膜特性及处理受污染原水效果的影响

通过对普通石英砂(QS)进行氨基及铝钙双氢氧化物改性制得氨基改性砂(AMS)和铝钙双氢氧化物改性砂(CAS),分别以QS、AMS、CAS为滤料填充滤池进行挂膜,研究了不同石英砂表面的生物膜量、生物活性、胞外聚合物(EPS)的特性及对受污染原水的处理效果。结果表明,挂膜成功后CAS表面的生物活性最高,为42.00 mgO_(2)/(g·h),生物膜量和胞外聚合物的含量最大,分别为12.43 mg/g、105.09 mg/(g·SS),对COD_(Cr)、NH^(+)_(4)-N的去除率分别稳定在58.20%、89.50%;AMS表面的生物活性、生物膜量、EPS平均含量分别为32.97 mgO_(2)/(g·h)、9.07 mg/g、93.41 mg/(g·SS),对COD_(Cr)、NH^(+)_(4)-N的去除率分别为54.60%、85.10%。三种石英砂表面生物量分布均沿水流方向递减,EPS的含量从溶解性胞外聚合物(SL-EPS)到紧密附着性胞外聚合物(TB-EPS)呈上升趋势。

塔里木盆地库车山前超深气井砂垢堵塞成因及靶向解除技术

塔里盆地库车山前超深气田是西气东输主力气源地,具有超高温、超高压、高矿化度、储层裂缝非均质性强等特征,气井生产过程中砂垢堵塞问题突出,据统计最高影响气田产能达800×104 m^(3)/d。为实现超深气井高效解堵,通过气水两相结垢热力学预测模型、裂缝性储层岩石力学实验、井筒内气液固流动模拟等研究,揭示了超深气井砂垢复合堵塞成因,并形成了靶向解堵复产关键技术。研究结果表明:①“高温流动压降结垢、裂缝面破裂出砂”是超深气井出砂结垢的内在机理;②结垢固化松散砂桥形成复合堵塞是气井堵塞减产的主要原因,其中靶向除垢是解堵复产的关键所在;③靶向除垢解堵区域为井筒变径处和井周5 m内基质—裂缝系统,气井堵塞率30%~60%为最佳解堵时机;④非酸性除垢解堵液相比常用的酸性解堵液,在同级别溶垢能力的基础上,腐蚀速率降至0.49 g/(m^(2)·h),可同时满足低腐蚀和高效除垢的技术要求。结论认为,形成的超深气井靶向除垢解堵技术在塔里木盆地库车山前超深气田规模应用159井次,有效率达93.3%,累计增产天然气75.08×10^(8)m^(3),已成为西气东输主力气井快速解堵复产的“冬保良方”,可为国内外同类气田解堵复产提供技术借鉴。

考虑组构演化的砂砾土弹塑性本构模型

考虑组构演化效应对于真实、准确地描述无黏性土在循环加载过程中的宏观力学行为具有重要意义。在砂砾土单调加载条件下构建的非线性剪胀方程的基础上,引入反映其循环荷载条件下剪胀阶段组构演化的剪胀内变量,基于广义塑性理论框架建立了反映砂砾土静力及液化全过程力学特性的弹塑性本构模型。对比考虑组构演化效应前后砂砾土液化变形、应力路径和超孔隙水压力发展规律,说明了组构演化效应对于模拟砂砾土液化响应的重要影响。通过开展一系列砂砾土静、动力大型三轴试验并结合相关文献试验结果对模型性能进行了验证。结果表明该模型总体上能够合理反映砂砾土在静力排水条件下应力-应变-体变特性以及在液化过程中超孔隙水压力的累积与消散、应力路径演化和液化变形发展情况,可为砂砾土工程数值模拟提供有力的本构工具。

地震构型分析方法在胜坨油田辫状河储层表征中的应用

辫状河沉积砂体储层内部的复杂结构是控制砂体连通性的根本原因,它制约了碎屑沉积储层的剩余油开发。以往依靠井数据的砂体构型表征精度取决于井控程度,井间预测由于缺乏数据支持而存在不确定性。因此,砂体构型精细表征的关键在于使用地震数据进行井间预测。研究表明,通过划分复合心滩坝砂体的单井构型相,结合地震正演分析确定地震可辨识构型模式,利用地震构型分析方法预测地震构型相和构型边界的平面分布特征,能够为井间预测提供客观数据支持。

定向钢纤维水泥基复合材料的含砂率及定向时程影响规律

为研究钢纤维水泥基复合材料中钢纤维定向分布规律,考虑定向时程和含砂率两种因素,基于团队自主研发的钢纤维定向设备,制作32个试件。在恒定磁场下,系统地开展了梯度定向时程与含砂率钢纤维定向试验,利用COMSOL有限元模拟定向试验磁场分布情况,通过CT-X射线扫描技术获取不同试件的截面图像,计算钢纤维的方向系数,讨论钢纤维受梯度定向时程与含砂率影响下的定向规律。研究结果表明:随着定向时程的增加,在相同含砂率条件下,钢纤维的方向系数在初始阶段迅速提升,然后逐渐减缓,最终趋于稳定;在相同定向时程下,含砂率过高或过低都会对钢纤维的定向效率产生不利影响,控制含砂率在40%左右时可以获得相对理想的钢纤维定向效果。