昆明地震台地面与井下地震观测背景噪声对比

对昆明地震台山洞内放置的宽频带地震仪BBVS-60及观测井内放置的GL-S60B深井宽频带地震仪所记录的资料,进行背景噪声对比分析,得到基岩地区地面及井下背景噪声干扰,为今后在云南地区推广井下观测提供参考依据。结果显示,在1—20 Hz频段内,井下台背景噪声RM_S值比地表台小,降噪效果UD向达30%以上,EW向达50%,NS向达60%。在100—30 s频带内噪声不降反升,原因有待进一步分析。     

深井电极交叉供电对自然电位的影响

通过实验论证平凉地震台深井电阻率观测自然电位畸变由电极交叉供电造成,讨论分析不同电极供电对自然电位的影响。结果表明:对测量极供电,会影响自然电位,不会影响电阻率测值;单极供电对自然电位的影响表现为阶跃突跳,并以指数形态恢复,恢复时间约10 h,干扰峰值与供电电流、供电时间等有关;对观测数据进行校正,取得较好效果。     

东海八角亭海洋深井台地震监测

上海市地震局设计、建设的中国第1个真正意义上的海洋深井地震观测台位于东海石油平台上,井深780 m,安装2套JDF-1型地震计进行观测。通过对陆域地震台站记录的大地震进行分析比较、方位校准,采用单台地震分析方法,确定2009年5月—2011年6月记录到的136个地震参数,总结海域地震波形特征。结果表明,该海域地震活动性特征与当地地质构造一致。     

气汞的第一个同震效应记录

利用杭州超距科技有限公司最近研发的ATG-6138型测汞仪在云南省弥勒井气汞（Hg）观测中记录到尼泊尔8.1级地震的同震效应。这是我国气汞观测的第一个同震效应的纪录。这一事实表明了进一步提升地震地下流体化学量观测仪器的观测精度与采样率,有可能记录到固体潮与同震效应等更多的地壳动力作用信息,从而进一步提升其地震前兆监测能力。     

Well tie for broadband seismic data

The seismic industry is increasingly acquiring broadband data in order to reap the benefits of extra low‐ and high‐frequency contents. At the low end, as the sharp low‐cut decay gets closer to zero frequency, it becomes harder for a well tie to estimate the low‐frequency response correctly. The fundamental difficulty is that well logs are too short to allow accurate estimation of the long‐period content of the data. Three distinctive techniques, namely parametric constant phase, frequency‐domain least squares with multi‐tapering, and Bayesian time domain with broadband priors, are introduced in this paper to provide a robust solution to the wavelet estimation problem for broadband seismic data. Each of these techniques has a different mathematical foundation that would enable one to explore a wide range of solutions that could be used on a case‐by‐case basis depending on the problem at hand. A case study from the North West Shelf Australia is used to analyse the performance of the proposed techniques. Cross‐validation is proposed as a robust quality control measure for evaluating well‐tie applications. It is observed that when the seismic data are carefully processed, then the constant phase approach would likely offer a good solution. The frequency‐domain method does not assume a constant phase. This flexibility makes it prone to over‐fitting when the phase is approximately constant. Broadband priors for the time‐domain least‐squares method are found to perform well in defining low‐frequency side lobes to the wavelet.     

Evaluation of ASCE 7 equations for designing acceleration‐sensitive nonstructural components using data from instrumented buildings

This study uses instrumented buildings and models of code‐based designed buildings to validate the results of previous studies that highlighted the need to revise the ASCE 7 F_p equation for designing nonstructural components (NSCs) through utilizing oversimplified linear and nonlinear models. The evaluation of floor response spectra of a large number of instrumented buildings illustrates that, unlike the ASCE 7 approach, the in‐structure and the component amplification factors are a function of the ratio of NSC period to the supporting building modal periods, the ground motion intensity, and the NSC location. It is also shown that the recorded ground motions at the base of instrumented buildings in most cases are significantly lower than design earthquake (DE) ground motions. Because ASCE 7 is meant to provide demands at a DE level, for a more reliable evaluation of the F_p equation, 2 representative archetype buildings are designed based on the ASCE 7‐16 seismic provisions and exposed to various ground motion intensity levels (including those consistent with the ones experienced by instrumented buildings and the DE). Simulation results of the archetype buildings, consistent with previous numerical studies, illustrate the tendency of the ASCE 7 in‐structure amplification factor, [1 + 2(z/h)] , to significantly overestimate demands at all floor levels and the ASCE 7 limit of to in many cases underestimate the calculated NSC amplification factors. Furthermore, the product of these 2 amplification factors (that represents the normalized peak NSC acceleration) in some cases exceeds the ASCE 7 equation by a factor up to 1.50.     

永清MS 4.3地震前永清井水温异常分析

2017年12月永清井观测温度急剧下降,采用该井水温、水位多年观测数据,从仪器测量原理及精细温度梯度测量出发,结合井孔资料,认为该变化为永清M_S 4.3地震（井震距<30 km）发生前的异常信息。利用正弦累加模型计算温度异常持续时间和幅度,发现该异常变化存在2个周期：①周期42天,温度变化幅度为0.042 12℃;②周期16.77天,温度变化幅度为0.018 62℃。分析认为,区域应力状态发生变化,使含水层渗透性受到影响,从而间接影响到井下温度传感器安放处水温。地震发生后近距离观测到水温异常变化尚属首次,利用模型对变化时间与幅度进行量化提取,可为经验预报、统计预报提供经典震例。     

基于数据融合的浅层地下水提取技术研究

为提高浅层地下水遥感探测的准确性和效率,开辟遥感找水新思路,首次将空间分辨率为30 m的Landsat-7ETM多光谱数据和空间分辨率为150 m(Wide Swath模式)的Envisat-1 ASAR先进合成孔径雷达数据进行了融合,并利用基于主成分变换(PCA)和小波变换(WT)的融合算法成功地找到了浅层地下水信息异常带。通过实地调查和物探、钻探验证,I、II、III级找水靶区的富水性情况与预测结果基本一致,并在上述靶区找到了丰富的浅层地下水,证实了该方法的可行性和实用性,可为今后地下水快速勘察提供新的技术手段。     

潮页1井钻探施工技术

潮页1井是在潮水盆地布置的第一口页岩气资源调查井,取心质量要求较高,地层有大段泥页岩层段,易水化剥落,施工难度大。本文着重介绍了潮页1井取心工艺、钻头选型、冲洗液技术及井斜控制技术等相关的施工经验。潮页1井采用大口径绳索取心技术,第四系地层以深全井取心,该技术在甘肃地区鲜有可供参考的施工案例,而该井岩心采取率接近90%。钻进过程中通过选用合理的钻进参数和护壁性能较强的冲洗液体系,解决了施工中遇到的地层“打滑”、井壁稳定性差等技术难点,保障了潮页1井的顺利完工。     

川藏铁路3000 m水平定向钻井技术方案

川藏铁路设计多条超长深埋隧道,且多处于高海拔、高陡斜坡及雪线以上的无人山区,地形险峻,起伏大,交通条件差。沿隧道轴线的水平定向钻井为隧道勘察提供了一种有效的勘察手段。结合工程及地层特点,从钻井设备、工艺等方面,为超长隧道勘察提供了一种3000 m级水平定向钻井技术方案。方案明确了井身结构、全面钻进和长钻程取心钻进工艺、钻井液措施及部分复杂情况应对措施。以较少的钻探工作量,为隧道勘察提供更加详细的实物地质资料,真实反映隧道内的地质情况。