基于黏声介质的角度域高斯束逆时偏移方法研究

高斯束逆时偏移是一种兼具计算效率和成像精度的深度域成像方法,能够面向目标成像.地下介质中黏滞性普遍存在,利用传统各向同性或完全弹性的成像方法处理黏滞性探区的数据会降低分辨率,并导致成像位置不准确和振幅欠估计等问题.本文在高斯束逆时偏移的基础上,通过对震源点和检波点处的波场进行衰减补偿,并结合高斯束求解时的角度信息,实现了黏声介质角度域高斯束逆时偏移方法.最后通过模型和实际资料试算对本文方法的正确性和适用性进行了验证.试算结果表明:相比于声波高斯束逆时偏移,本文方法能够对黏滞性引起的吸收衰减进行有效补偿,同时提取的角度域共成像点道集(ADCIGs)不仅可以用于分角度叠加成像压制成像噪声,而且能够为后续的偏移速度分析提供支撑.     

智能化地震会商系统设计、原理及在地震分析预报中的应用

为适应地震会商业务信息化需求,支撑地震业务数据加工、处理、统计分析和模型计算等工作,设计地震会商技术系统软件平台。该系统以自定义流程为驱动,灵活适应需求变更,引入低代码开发技术策略,通过开放平台,提供专业用户参与开发和自定义云端部署的全套技术解决方案。为适应地震分析预报的科研型业务特点,在系统构建过程中引入敏捷式开发理念,有效填补了科研成果到业务应用转化的鸿沟。经3年建设实践,该系统于2019年在地震系统业务单位试点应用,试用结果证明,系统设计模式和使用方法符合地震会商业务特点,行业内现有用户已突破2000人。     

芦山地震断层的滑动分布与汶川地震断层的关系

本文利用2013年芦山M_S7.0级地震同震GPS数据反演了芦山断层几何与断层滑动分布,结果表明:芦山地震发震断层具有南陡北缓、上陡下缓的特征,低倾角的区域位于发震断层北段且靠近映秀断层的一侧;滑动分布模型的最大滑动量为0.82m,其深度为13.67km与小震发生集中平均深度12.5km接近.我们选取1998—2014年龙门山断裂带区域地壳形变观测数据,拟合获得了龙门山断裂带走向方向上的速度分量,发现在汶川M_S8.0地震与芦山M_S7.0地震之间宽度约30km破裂空区,龙门山断裂带西南段与东北段的形变分量以破裂空区为界方向相反.断裂带东北段(汶川地震主要发震断层)的形变分量方向与断层右旋走滑运动方向一致,而在断裂带西南段(芦山地震发震断层)的形变分量方向与断层左旋走滑运动方向一致.芦山地震走滑方向与汶川地震走滑方向相反是因为该断裂带构造运动在特有几何构造下受青藏高原东南向挤压,遇龙门山中段岩石圈楔状构造的阻挡,在汶川M_S8.0地震与芦山M_S7.0地震间的地震空区,形成了构造运动向其两侧分流的结果.     

主动震源在中国区域尺度及水库地震监测中的应用

综述精密可控震源与陆上气枪2种主动震源特性及在国内区域尺度上的应用,估算观测介质波速随时间变化的精度,探讨主动震源在构建水库地震观测介质波速随时间变化中的系统应用。     

Amplitude variation with incident angle and azimuth inversion for Young's impedance,Poisson's ratio and fracture weaknesses in shale gas reservoirs

By analogy with P- and S-wave impedances, the product of Young's modulus and density can be termed as Young's impedance, which indicates the rock lithology and brittleness of unconventional hydrocarbon reservoirs. Poisson's ratio is also an effective indicator of rock brittleness and fluid property of unconventional reservoirs, and fracture weaknesses indicate the fracture properties (fracturing intensity and fracture fillings) in fracture-induced unconventional reservoirs. We aim to simultaneously estimate the Young's impedance, Poisson's ratio and fracture weaknesses from wide-azimuth surface seismic data in a fracture-induced shale gas reservoir, and use the horizontal transversely isotropic model to characterize the fractures. First, the linearized PP-wave reflection coefficient in terms of Young's impedance, Poisson's ratio, density and fracture weaknesses is derived for the case of a weak-contrast interface separating two weakly horizontal transversely isotropic media. In addition, an orthorhombic anisotropic case is also discussed in this paper. Then a Bayesian amplitude variation with incident angle and azimuth scheme with a model constraint is used to stably estimate Young's impedance, Poisson's ratio and fracture weaknesses with only PP-wave azimuthal seismic data. The proposed approach is finally demonstrated on both synthetic and real data sets with reasonable results.     

基于正则化条件的地震数据局部信噪比估计方法

信噪比是衡量地震数据质量的重要指标之一,在地震数据处理和解释中有着重要的作用.目前已有的地震数据信噪比估计方法往往得到的是整个数据的全局信噪比,这种方法只能说明地震数据总体质量的好坏,无法直观细致地刻画地震信号的局部质量.本文提出一种基于正则化条件的局部信噪比估计方法.该方法的基本原理是使用正则化共轭梯度法求解局部信噪比最优解,正则化算子的参数将控制地震信号各点数据局部信噪比的平滑性.其中应用一种基于"过滤波"的级联信号估计方法来计算有效信号,该方法利用有效信号和噪声的相关性特征计算局部信噪比中的有效信号.局部信噪比估计方法利用了信号中每个数据点及其邻域各点的局部信息,避免了使用单个数据点而可能出现的信噪比不合理值,而且局部处理能够减少全局噪声对信噪比估算的影响,该方法可以更准确地表征地震资料信噪分布特征.另外,局部信噪比对去噪方法的评估也具有重要意义.理论模型测试和实际资料处理结果表明,局部信噪比估计方法能够准确反映任一给定地震信号剖面的局部信噪比特征,为非平稳地震数据质量评估提供了直观的评判标准.     

Estimating gas saturation in a thin layer by using frequency‐dependent amplitude versus offset modelling

Various models have been proposed to link partial gas saturation to seismic attenuation and dispersion, suggesting that the reflection coefficient should be frequency‐dependent in many cases of practical importance. Previous approaches to studying this phenomenon typically have been limited to single‐interface models. Here, we propose a modelling technique that allows us to incorporate frequency‐dependent reflectivity into convolutional modelling. With this modelling framework, seismic data can be synthesised from well logs of velocity, density, porosity, and water saturation. This forward modelling could act as a basis for inversion schemes aimed at recovering gas saturation variations with depth. We present a Bayesian inversion scheme for a simple thin‐layer case and a particular rock physics model and show that, although the method is very sensitive to prior information and constraints, both gas saturation and layer thickness theoretically can be estimated in the case of interfering reflections.     

浙江省地震观测台站综合防雷系统升级

以2014年浙江省地震局5个地震台站进行综合防雷系统升级改造为例,阐述浙江省数字观测台站雷击隐患,从配电系统、接地系统、通信系统和综合布线等方面出发,结合台站实际情况,对地质环境特殊的台站进行针对性防护,总结此次防雷系统改造的实际效果,分析不足之处,提出后续改造建议。     

智能化地震会商系统设计、原理及在地震分析预报中的应用

为适应地震会商业务信息化需求,支撑地震业务数据加工、处理、统计分析和模型计算等工作,设计地震会商技术系统软件平台。该系统以自定义流程为驱动,灵活适应需求变更,引入低代码开发技术策略,通过开放平台,提供专业用户参与开发和自定义云端部署的全套技术解决方案。为适应地震分析预报的科研型业务特点,在系统构建过程中引入敏捷式开发理念,有效填补了科研成果到业务应用转化的鸿沟。经3年建设实践,该系统于2019年在地震系统业务单位试点应用,试用结果证明,系统设计模式和使用方法符合地震会商业务特点,行业内现有用户已突破2 000人。     

Long-range forecasting of suspended sediment

This study examines the employment of two methods, multiple linear regression (MLR) and an artificial neural network (ANN), for multistep ahead forecasting of suspended sediment. The autoregressive integrated moving average (ARIMA) model is considered for one-step ahead forecasting of sediment series in order to provide a comparison with the MLR and ANN methods. For one- and two-step ahead forecasting, the ANN model performance is superior to that of the MLR model. For longer ranges, MLR models provide better accuracy, but there is an important assumption violation. The Durbin-Watson statistics of the MLR models show a noticeable decrease from 1.3 to 0.5, indicating that the residuals are not dependent over time. The scatterplots of the three methods (MLR, ARIMA and ANN) for one-step ahead forecasting for the validation period illustrate close fits with the regression line, with the ANN configuration having a slightly higher R² value.