基于横波速度差异的裂缝分布识别方法——以准噶尔盆地火山岩地层为应用实例

在火成岩等裂缝和微裂缝发育地层的钻井过程中,井壁掉块甚至井壁坍塌引起的卡钻事故时有发生,严重影响了钻井安全和施工进度,要解决上述问题,需要在钻前了解地层的裂缝分布情况,进而设计合理的井身结构并采用有针对性的钻井工艺。为此,在详细分析声波速度与岩石力学特征参数关系的基础上,给出了以声波测井数据为依据的裂缝概率分布的定量计算方法,并且通过分析井径对声波时差影响的机理,提出了井径对声波时差影响的校正方法,进而建立了基于声波测井数据的裂缝识别模型。将该模型应用于准噶尔盆地2口深探井,应用效果表明:1裂缝识别结果与井径分布情况吻合较好,从而反映出该方法能够较准确地对裂缝进行识别;2井径变化对于声波时差会产生较大的影响,在数据处理过程中必须进行校正;3该方法利用常规的声波测井数据进行裂缝识别,也为一些仅有常规测井资料的老井进行裂缝识别提供了一条新的途径。     

岩石中应力弛豫的衰减和模量色散

本文在低频和声频范围内研究了砂岩、大理岩及花岗岩在不同饱和液体情况下的衰减和模量随温度的变化，同时还探讨了衰减与激发频率、共振振幅的关系。并根据时温等效原理，得出了饱和原油砂岩在衰减～温度港上28℃的衰减峰应该与衰减～频率港上8．9HZ的衰减峰相对应的结论。     

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渤海浅层油气田以上第三系明化镇组下段河流相地层为主，沉积环境横向变化剧烈，储层横向预测难度大，文章针对这一问题进行了研究。对两个有代表性的渤海浅层油气田的40多口钻井的测井和地震资料进行了综合研究，建立了研究区河流相的沉积体系，划分了沉积微相的类型，确立了主要沉积微相的地质相、测井相及地震相特征和识别标志；在精细划分沉积相的基础上，研究了主要河流沉积微相类型与地层速度密度和波阻抗的关系。研究发现，本区沉积微相对某些地球物理参数有明显控制作用，统计拟合的主要沉积微相和速度密度及波阻抗随深度的变化曲线符合二次曲线的变化规律，文章给出了相应的数学表达式；本区85%的油气储层为边滩砂体，在明化镇组下段的不同深度上边滩的波阻抗和密度与其他微相有明显差别，故利用这一规律对地震反演的波阻抗或密度资料做进一步处理，可将边滩砂体单一提取出来，进而实现在沉积规律控制下横向外推预测含油气储层和单个砂体。     

金属型场发射阵列的研究

讨论了Ｓｐｉｎｄｔ方法制作金属型ＦＥＡ工艺过程中的技术难点和相应的解决方案,最后成功地研制出场发射阵列,并实现了场发射。     

热噪声复合环境试验装置研制及其能力验证

研制一套小型热噪声试验装置,开展单一噪声环境、单一热环境、热噪声复合环境施加能力的试验验证,结果表明该装置可实现试验件表面同侧热环境超过600℃、噪声环境超过165 dB的联合施加,可为大型热噪声试验系统研制、热结构设计、试验方案确定等提供技术支撑。     

长脉冲微波热声效应的实验研究

微波热声效应是一种生物组织在微波脉冲信号的照射下向外辐射声波信号的特殊现象,产生的声波信号携带着生物组织对微波信号的吸收特性,以及生物组织吸收微波能后发生的一系列生物化学物理反应的变化等信息。本文介绍了电子科技大学设计、搭建的一套脉冲宽度6ms,功率约800W的长脉冲微波热声效应实验系统,并介绍了初步实验研究结果。结果表明在长脉冲条件下,微波热声效应与微波的脉冲特性有复杂的关联性,内涵丰富的物理化学机制,具有很大的潜在研究价值。     

车用汽油机全甲醇改造的排放与燃烧特性

本文介绍了车用点燃式发动机应用甲醇燃料的试验研究结果,通过分析甲醇机的排放性能及燃烧特征,指明了甲醇发动机低排污、高效率运行的途径,对车用汽油机的全甲醇改造有重要参考价值。     

玻璃纤维/大麻纤维增强聚丙烯混杂复合材料的力学性能和断裂特征(英文)

目前在土木工程,建筑,汽车等领域里使用的复合材料中,玻璃纤维是用量最大的增强材料。由于保护地球环境的呼声日趋高涨,天然纤维被期待着代替源于石油而且再利用困难的玻璃纤维,成为绿色复合材料的必要材料之一。本文通过注射成型工艺制作了玻璃短纤维,大麻短纤维以及混杂型纤维增强复合材料,并在拉伸实验中应用两种不同频率的声发射技术检测了拉伸断裂特性。实验发现,随着大麻纤维的加入和混杂复合材料绿色度的增加,复合材料的拉伸弹性模量随之线性增大,而拉伸强度基本保持不变。当大麻纤维的含量超过20wt%的时候,拉伸强度开始降低。在不同频率的声发射实验中,混杂型复合材料的声发射事件的产生都比单一纤维增强型复合材料要来的晚,也就是说,纤维的混杂有助于推迟微裂纹的产生。     

Improving Source Location Accuracy of Acoustic Emission in Complicated Structures

To determine failure locations is a practical effort in many engineering applications. A proper selection of signal wave velocity is critical for the implementation. Current practice in AE using a constant velocity model has a serious disadvantage that may introduce significant error and slow the speed of convergence, and it becomes even worse when the material is in form of complicated structure. In this paper, we proposed a variable velocity model to address this disadvantage. The variable velocity approach is validated by static tests (pencil lead break) and dynamic tests (fatigue tests) performed on a cemented total hip arthroplasty (THA) that has four material layers. Compared to the constant velocity model, the variable velocity approach reduces source location errors in both static (from 7.1 mm to 4.7 mm) and dynamic tests. The results indicated that the proposed variable velocity approach has significant advantages over the constant velocity approach when microcracks occur in a complicated structure.     

Estimating the flow velocity and discharge of ADCP unmeasured area in tidal reach

Due to the ringing and side-lobe interference, acoustic Doppler current profiler (ADCP) is unable to accurately capture the complete velocity profile in open channels near the water surface and channel bottom, which are usually called unmeasured areas. At present, the flow velocities through the unmeasured areas are most commonly estimated using the power law with the power set to be the default value. However, since the flows are unsteady and nonuniform in tidal reaches, the velocity distribution model and corresponding parameters will vary with the bathymetric, tide period, etc. Therefore, the most common estimation with the power law may not be suitable in tidal reaches. In this paper, a simple determination method of the best model is proposed. Firstly, the parameters in three classical velocity distribution models, which are called power law, logarithmic law and parabolic law models, are solved by least squares based on the ADCP measured velocity cells. Then, the corresponding root-mean-square error (RMSE) of each model is used for the quantitative indicator that the model with the minimum RMSE is chosen as the best model. At last, the flow velocity and discharge of the unmeasured area are estimated by the best model. The experiments carried out in the tidal reach of Yangtze Estuary showed that vertical flow velocity distribution various with the bathymetry and tide period, and the best models averagely improved about 2.0% of the relative standard deviation (RSD) relative to the power law method in the discharge estimation, especially at some tide period the RSD of the best model was several times better than that of power law model. For Yangtze River with an annual average discharge of 3.0×10⁴ m³/s, the improvement should not be ignored. Therefore, it will be necessary to use the best model with minimum RMSE to estimate the flow velocity in tidal reach.