中国大陆科学钻探先导孔零偏VSP资料解释   总被引：3，自引：3，他引：0  

姜修道  朱光明  朱龙生  张文波  李桂花 《地球科学与环境学报》2004,26(1):55-60

用六级三分量检波器在中国大陆科学钻探先导孔中实施了零偏VSP测量.数据处理结果表明,中国大陆科学钻探孔区超高压变质岩石的地震波速度主要介于4500～7000m/s之间,显著高于一般的沉积岩地区,而且随深度变化不明显.声波测井速度系统地稍低于VSP层速度,可能是由于井壁处岩石的完整性受到破坏而造成的.地震波速度与岩石密度和岩性存在明确的对应关系,榴辉岩的密度和地震波速度均显著高于片麻岩类岩石;由榴辉岩退变生成的斜长角闪岩类岩石,其密度和地震波速度均呈现出较大的变化,主要与其退变质程度有关;超基性岩中的裂隙系统导致其密度和地震波速度大幅度下降.由于榴辉岩与其他岩石类型之间存在较大的波阻抗差异,因此用零偏VSP资料标定该区地震波的地质层位是有效的.关于地震波反射的原因,通过综合研究地震波(包括反射纵波、上行转换横波、井筒波)的特征、岩石速度和密度分布以及井径变化,认为主要是岩性分界面、韧性剪切带和断裂(带),但还有一些因素尚待进一步研究.  相似文献   

利用p~3软件进行GPS单点定位解算的若干问题     

FENG Bao-hong  GAO Cheng-fa 《测绘学院学报》2008,(4)

利用p3软件对大量实测数据进行了高精度单点定位有关问题的验证和分析;在IGS提供的精密星历和卫星钟差产品中,较为深入地比较分析了快速产品和几种最终产品的定位精度、收敛速度及p3软件的正反算结果精度。得出以下结论:快速产品与最终产品的定位精度和收敛速度相似;COD的收敛速度和定位精度最高;p3软件的反算精度明显优于正算,且精度也比较均匀。这些研究成果对PPP技术的实际应用具有较好的借鉴意义。  相似文献   

Weak-contrast approximation of the elastic scattering matrix in anisotropic media     

Bjørn Ursin  Geir U. Haugen 《Pure and Applied Geophysics》1996,148(3-4):685-714

The plane-wave reflection and transmission coefficients at a plane interface between two anisotropic media constitute the elements of the elastic scattering matrix. For a 1-D anisotropic medium the eigenvector decomposition of the system matrix of the transformed elasto-dynamic equations is used to derive a general expression for the scattering matrix. Depending on the normalization of the eigenvectors, the expressions give scattering coefficients for amplitudes or for vertical energy flux.Computing the vertical slownesses and the corresponding polarizations, the eigenvector matrix and its inverse can be found. We give a simple formula for the inverse, regardless of the normalization of the eigenvectors. When the eigenvectors are normalized with respect to amplitudes of displacement (or velocity), the calculation of the scattering matrix for amplitudes is simplified.When the relative changes in all parameters are small, a weak-contrast approximation of the scattering matrix, based on the exactly determined polarization vectors in an average medium, is obtained. The same approximation is also derived directly from the transformed elasto-dynamic equations for a smooth vertically inhomogeneous medium, proving the consistency of the approximation.For monoclinic media, with the mirror symmetry plane parallel to the interface, the approximative scattering matrix is given in terms of analytic expressions for the non-normalized eigenvectors and vertical slownesses. For transversely isotropic media with a vertical axis of symmetry (VTI) and isotropic media, explicit solutions for the weak-contrast approximations of the scattering matrices have been obtained. The scattering matrix for amplitudes for isotropic media is well known. The scattering matrix for vertical energy flux may have applications in AVO analysis and inversion due to the reciprocity of the reflection coefficients for converted waves.Numerical examples for monoclinic and VTI media provide good agreement between the approximative and the exact reflection matrices. It is, however, expected that the approximations cannot be used when the symmetry properties of the two media are very different. This is because the approximation relies on a small relative contrast between the eigenvectors in the two media.Presented at the Workshop Meeting on Seismic Waves in Laterally Inhomogeneous Media, Castle of Trest, Czech Republic, May 22–27, 1995.  相似文献   

VSP资料约束地层反滤波研究   总被引：2，自引：0，他引：2  

WANG Yu HAN Li-guo CUI Jie College of GeoExploration Science  Technology  Jilin University  Changchun  China 《吉林大学学报(地球科学版)》2006,(Z2)

浅地表的低速带和地层滤波作用导致地震信号的能量衰减,地震子波的高频快速衰减,速度频散的子波变形,对地震底层分析带来了严重的影响。地层反滤波算法就是为了消除地层对子波的影响,利用VSP中的直达下行波推算出每个地层滤波算子,计算出各个地层滤波算子的反算子,然后利用这些反算子恢复出地表记录中损失掉的高频成分,减弱地层滤波对波形的影响,增加地表记录的频率成分和波形的准确度。分析实际地震资料表明,经过地层反滤波处理后的记录频率成分明显提升,地质构造更加准确、清晰。  相似文献   

鄂尔多斯盆地苏里格庙气田上古生界盒8段地质与地球物理响应特征     

王志雄  徐国盛 《物探化探计算技术》2004,26(1):27-32

苏里格庙气田主要产气层为上古生界石盒子组盒8段，属于三角洲平原分流河道沉积。复合砂体近南北向展布；单砂体的厚度变化大，非均质性明显，储渗变化大。盒8段含气砂岩在AVO资料上有明显反映；在综合测井资料上，盒8段表现出自然伽玛测井值、密度测井值、补偿中子测井值都偏低，电阻率、声波时差测井值较高，出现了大幅度的自然电位异常。利用核磁共振测井技术测得苏里格庙区某井盒8段3555．9m～3559．6m为气层，3560．6m～3572m为气水层，与生产实践吻合得很好。  相似文献   

Detection of Methane Hydrate-Bearing Zones from Seismic Data     

Takao Inamori  Masami Hato 《Resource Geology》2004,54(1):99-104

Abstract. The MITI Nankai Trough wells were drilled offshore Japan in the Tokai area in 1999 and 2000. The occurrence of methane hydrate was confirmed by various indicators in the borehole logs and from core data. These findings have a large impact on potential future Japanese energy resources and other related-scientific interests.
We first tried to find the methane hydrate-bearing zones using interval velocities derived from NMO velocity analysis. However, this analysis produced poor resolution. To achieve a more detailed delineation of the gas hydrate- and gas-bearing zones, we executed a seismic impedance inversion calibrated by the logs from two of the MITI Nankai Trough wells. Although these two wells are only about 90 m apart, we were able to produce an impedance section with fine detail by adopting a simple initial model and incorporating physical properties of the methane hydrate-bearing zones. The locations of the methane hydrate-bearing zones are readily apparent in the final section.  相似文献   

Policy options to streamline the carbon market for agricultural nitrous oxide emissions     

Meredith T. Niles  Hannah Waterhouse  Robert Parkhurst  Eileen L. McLellan  Sara Kroopf 《Climate Policy》2019,19(7):893-907

The majority of emissions of nitrous oxide – a potent greenhouse gas (GHG) – are from agricultural sources, particularly nitrogen fertilizer applications. A growing focus on these emission sources has led to the development in the United States of GHG offset protocols that could enable payment to farmers for reducing fertilizer use or implementing other nitrogen management strategies. Despite the development of several protocols, the current regional scope is narrow, adoption by farmers is low, and policy implementation of protocols has a significant time lag. Here we utilize existing research and policy structures to propose an ‘umbrella’ approach for nitrogen management GHG emissions protocols that has the potential to streamline the policy implementation and acceptance of such protocols. We suggest that the umbrella protocol could set forth standard definitions common across multiple protocol options, and then modules could be further developed as scientific evidence advances. Modules could be developed for specific crops, regions, and practices. We identify a policy process that could facilitate this development in concert with emerging scientific research and conclude by acknowledging potential benefits and limitations of the approach.

Key policy insights

• Agricultural greenhouse gas market options are growing, but are still underutilized

• Streamlining protocol development through an umbrella process could enable quicker development of protocols across new crops, regions, and practices

• Effective protocol development must not compromise best available science and should follow a rigorous pathway to ensure appropriate implementation

  相似文献   

一种基于灰色神经网络的卫星钟差预报策略     

闵扬海  王潜心  丛丽娟 《测绘科学》2019,44(8):190-198

针对钟差预报中灰色神经网络模型种类较多、性质和适用范围尚未具体分析的问题,根据其预报特点,该文提出了一种基于灰色神经网络的自适应钟差预报策略。基于MGEX精密钟差数据进行预报实验,采用不同建模钟差数据量进行相同时间段钟差预报,对3种不同的灰色神经网络模型钟差预报效果进行对比,总结了几种预报模型的性质与适用范围。该文提出的自适应预报策略较好地平衡了几种灰色神经网络模型的特点,提升了钟差预报效果。基于该文策略的实验结果表明:所提策略能够有效利用不同灰色神经网络模型特点,提高钟差预报精度。在1d预报中,该策略较本文提及的其他可靠方法精度提升1%~3%;6h预报中,该策略较较灰色模型等精度提高0.02~0.09ns。  相似文献   

实时卫星钟差基准精化方法          下载免费PDF全文

张东  宋伟伟  楼益栋  陈亮 《全球定位系统》2019,44(2):21-28

在基于精密单点定位(PPP)的授时方法中,卫星钟差产品的高精度时间基准至关重要.针对实时卫星钟差产品时间基准不够稳定的问题,本文采用一组具有原子钟外部输入的国际全球卫星导航系统(GNSS)服务(IGS)跟踪站建立了顾及原子钟变化特性的基准精化方法.该方法首先采用阿伦方差对不同的IGS跟踪站外接原子钟进行稳定度分析,挑选出一组稳定度高的原子钟用以精化时间基准.在此基础上,利用阿伦方差分析各台原子钟的噪声参数特征,并确定不同原子钟之间的权比关系.最终,建立时间基准改正量的随机模型,并计算出精化后的时间基准.通过实例验证表明:与IGS事后精密钟差产品定义的时间基准比较,改正后的实时钟差基准单天内的标准差(STD)优于0.1 ns,相比于改正前最高提升了93%.同时,基准改正后的天内万秒稳达到10^-15量级,实现了一个量级的提高.此外,通过相对钟差精度的分析,表明钟差基准修正不影响PPP的定位精度.  相似文献   

BDS卫星钟差半参数平差模型异常数据探测与处理     

李文涛  颜雄  夏磊  任青阳  陈洁  潘雄 《测绘学报》2020,49(1):55-64

针对北斗卫星钟差数据中出现钟跳、粗差等异常数据频次较高的问题,将半参数平差模型引入BDS的钟差数据的处理过程中。首先,在考虑系统误差的同时,改进了常用的钟差模型;其次,综合考虑异常数据和系统误差,利用补偿最小二乘原理和极值求解方法,详细推导了分离异常数据前后参数和非参数估计值与相应观测值改正数的关系表达式,实现了异常数据的定值、参数求解和系统误差分离。在此基础上,引入Cook距离,给出了利用参数分量和非参数分量的Cook距离及混合Cook距离,去判断异常值的位置,并给出了一些参数的选取方法及相应的处理措施,实现了卫星钟差异常数据的定位和定值以及部分系统误差的分离。最后,采用武汉大学GNSS中心提供的采样间隔为5 min的北斗卫星精密钟差数据,将本文方法与常用方法进行了试验对比。试验结果表明,本文方法能够有效地识别并处理卫星钟差数据中的异常值,有效克服了基于经验阈值钟差异常数据探测方法的不足,且该方法对于量级较小的异常钟差数据也有很好的探测效果,一定程度丰富了现有的BDS钟差数据质量控制方法。  相似文献