Continuously moving seismic sources, such as vehicles and train cars, play a crucial role as passive sources for nondestructive exploration in urban areas. Seismic interferometry is commonly used in field data acquisition and processing using linear arrays. However, the simultaneous recording of high-energy noise, excited by buildings and factories, cannot be overlooked. We simulate moving-source seismic records with strong noises using orthogonal arrays. When strong noise originates from specific angles, the energy-phase velocity curves of arrays in different directions significantly diverge. We determine that an L-shaped array, formed by orthogonal arrays, can effectively mitigate this effect, yielding more consistent results. Nonetheless, spatial constraints often preclude the deployment of L-shaped arrays. To mitigate this issue, we develop a new parallel observation system. Field tests conducted on a main road validate that the new array is comparable with the L-shaped array in terms of dispersion extraction. Similar to synthetic data, the phase velocity extracted from the linear array field data is found to be unreliable. Drilling data align well with the inversion results of the parallel observation system. Given the challenges of urban traffic-induced signal acquisition, deploying multiazimuth arrays to minimize noise impact is essential. Considering the spatial limitations, the convenient parallel observation system emerges as a good choice.

Subway tunnels are often built under the arterial roads in cities and the safety of overlying strata is important. Due to the limitation of urban space, many geophysical exploration methods maybe not be applicable. Most of the near surface exploration are carried out along the roads. This makes the continuously moving sources, including the vehicle and metro, to become important passive sources in the seismic detection. This type of signal has the characteristics of wide distribution, strong amplitudes, easy collection, and strong correlation. It carries abundant near-surface information and has high potential in non-destructive detection and monitoring. We obtain both the S-wave and P-wave profile with vehicle signals. Firstly, we propose an efficient method for equidistant linear array to extract the dispersion curves. The multiple vehicles signals were simulated with path integration method and the extracted dispersion curve has a good agreement with the theoretical data. In engineering and petroleum exploration, the P-wave velocity is more important than S-wave velocity sometimes. Previous study has shown that Poisson’s ratio is sensitive to the wavelength (W)-depth (D) relationship. Based on this observation, we proposed an inversion method to estimate the P-wave velocity structures directly. The traditional method is improved by adding the W/D-D information to the objective function, which is more sensitive to superficial layers. We select a high unevenness road above the operating subway. The vehicle signals are recorded along the roadside and the dispersion data is extracted. The inverted S-wave velocity profile can be used to identify warning geological positions such as water-rich weak interlayers. The resulting P-wave profile is also consistent with the drilling data. Our work successfully proves the effectiveness of vehicle signals and maps the overlying layers profile of subway tunnel.

Yammama formation of Lower Cretaceous period in Southern Iraq deposited massive bioclastic limestone of carbonate ramp, in which the mound-shoal complex (MSC) is the dominant reservoir contributor. Seismic attributes expression and the sedimentary evolution analysis can be used to better understand the deposition and distribution of the MSC. We summarized the seismic response characters of bioclastic limestone by analyzing seismic amplitude, phase etc., and then realized the seismic attributes expression of the MSC in the bioclastic limestone by multi-attribute blending and 3D visualization etc., revealing its stratigraphic sequence and sedimentary evolution. The MSC is characterized as high porosity as well as high permeability, resulting in low velocity, low density and low acoustic impedance in rock properties, and local strong reflections in seismic responses. The distribution of the MSC is mainly located at structure-high with periodic deposition on both wings of the anticline. This paper indicates that the MSC, the dominant reservoir of Yammama bioclastic limestone in the Lower Cretaceous period, is mainly controlled by micro-facies, and formed in the carbonate ramp of shallow water, which can deepens the understanding of its seismic attributes expression, spatial distribution as well as the sedimentary evolution.

In exploration and earthquake seismology, most sources used in subsurface structure imaging and rock property estimation are fixed in certain positions. Continuously moving seismic sources, such as vehicles and the metro, are one kind of important passive sources in ambient noise research. Commonly, seismic data acquisition and processing for moving sources are based on the assumption of simple point passive sources, and the dispersion curve inversion is applied to constrain near-surface velocity. This workflow neglects the Doppler effects. Considering the continuously moving properties of the sources, we first derive the analytical solution for the Rayleigh waves excited by heavy vehicles and then analyze their Doppler effects and dispersion curves. We observe that the moving source data have the Doppler effect when compared with the changes in the frequency of the source intensity, but this effect does not affect the frequency dispersion of Rayleigh waves. The dispersion curves computed for moving source records are consistent with the analytical dispersion solutions, which provide a theoretical foundation for velocity estimation using moving source data.

The application of Rayleigh waves in geological prospecting and engineering has been widely tested and used as a new method of shallow seismic exploration. The previous method of surface wave inversion needed to calculate the corresponding phase velocity that satisfied the dispersion function. This process increases the computation amount and reduces the surface wave inversion efficiency. This paper proposes a method to solve the problem by using different definition methods of the objective function. The method greatly reduces the amount of computation while results in approximately equal results with traditional method. This cuts the inversion time to 1% of conventional methods and provides favorable conditions for multiple inversions to suppress multiple solutions. We set artificial initial parameters with linear constraints in our velocity increasing model test to accelerate the convergence rate of the target function and obtain accurate results quicker. Finally, this method is applied to the microtremor dispersion data with a strong disturbance, and the inversion results are consistent with the high-density electrical profile and geological survey data.

The rich water goaf is one of the primary factors that endanger the safety of the foundation engineering, which will lead to the problems such as setting of ground. It is the method to detect the water-rich goaf accurately, efficiently and lossless that should be solved in engineering geophysics. According to the relationship between saturated water content and different porosity as well as S-shear velocity, this article documents the first application of the microtremor survey method to map the water-rich goaf. Compared with the high-density electrical method, the method is more accurate for the anomaly detection of the water-rich goaf. In the known goaf area, which belongs to one construction project department of the Qingdao Metro Line 8, the S-shear velocity profile using the 2D microtremor method can clearly depict the goaf position, which matches well with the high-density electrical inversion results and drilling data. The microtremor exploration method is proven to be an effective exploration method for mapping water-rich goafs, therefore, microtremor exploration method have technical advantages and bright application prospects for the detection of underground anomalous water-rich areas in engineering construction. Presentation Date: Tuesday, September 17, 2019 Session Start Time: 1:50 PM Presentation Start Time: 2:15 PM Location: Poster Station 3 Presentation Type: Poster

陆上三分量地震勘探中面波通常会严重降低资料品质并影响后续数据处理和最终综合解释结果.基于面波低速、低频和椭圆极化的特征,本文提出一种基于区域自适应极化滤波的面波压制方法.首先根据面波的视速度特性划分其主要分布区域,利用S变换进行区域滤波,初步分离出面波干扰;然后利用Hilbert-Huang变换(HHT)进行面波分析,得到面波的瞬时频率;再根据面波瞬时频率自动调节极化滤波的窗口大小,从而进行自适应极化滤波,将低频反射信号从面波干扰中分离出来;最后对区域滤波结果进行补偿,得到压制面波干扰后的最终地震记录.模型测试和实际数据处理结果表明,该方法能在有效压制面波的同时,较好地保护有效信号.

The exploration of the Rayleigh wave has been widely used in geological prospecting and engineering testing as a new method of shallow seismic exploration. The previous surface wave inversion method needs to calculate the phase velocity that satisfy the condition of the dispersion function equals, increasing the amount of calculation during forward modeling and lowering the velocity of inversion. This paper reduces the amount of calculation greatly by applying different definition methods of objective function and get approximately equal results, cutting the inversion time to 1% of conventional method and providing favorable conditions for multiple inversions to suppress multiple solutions. Finally the method is applied to the microtremor dispersion data with strong disturbance and the inversion results are consistent with the high-density electrical profile and geological survey data. Presentation Date: Wednesday, September 18, 2019 Session Start Time: 1:50 PM Presentation Start Time: 3:05 PM Location: 304B Presentation Type: Oral

中东地区大型油气藏多属于海相碳酸盐岩油气藏,其中白垩系生物碎屑灰岩油藏占据主要地位.地震数据中的采集脚印会对地震解释、属性分析、储层预测造成较大影响.采集脚印可以通过叠前地震数据处理流程消除,但处理流程用时较长且过程繁琐.利用采集脚印对地震属性的敏感特性,在二维波数域中将有效地质信号与采集脚印分离,并应用拉普拉斯高斯滤波器,实现了自适应去除采集脚印.通过压制采集脚印,提高了地震数据信噪比,为中东地区陆上大型生物碎屑灰岩油藏地震属性分析和储层预测提供了技术支撑.

动校正是地震数据处理的重要内容之一,采用常规动校正方法会产生拉伸畸变现象,在浅层和大炮检距处尤为明显,给地震资料的后续处理造成了不利影响.为此,分析了常规动校正方法产生拉伸畸变的原因,给出了动校正量可能的修正范围,提出了无拉伸畸变的动校正方法:①将近炮检距地震道进行常规动校正并叠加,得到标准道;②对地震道中每个时间样点的动校正量在给定的范围内进行修正扫描,并将常规动校正量加上修正量作为更新动校正量;③以待校正的时间样点为中心开时窗,使用更新动校正量进行动校正,并计算校正后时窗内数据与对应标准道数据的互相关系数;④将最大互相关系数对应的更新动校正量作为该样点的最终动校正量,以此实现无拉伸畸变动校正.模型数据测试和实际资料试处理结果显示了方法的正确性和有效性.

建立近地表横波速度模型时通常需要用到面波分析的方法.Love面波是在低速层分界面附近传播的一种SH型不均匀平面波,本文利用高阶有限差分算子、合理的自由地表边界条件以及CFS-CPML吸收边界条件,获得了高精度的Love面波波场记录,并与传统的分裂式完全匹配层得到的波场记录作对比,体现了CFS-CPML吸收边界条件的优越性.在此基础上将数值模拟提取的频散特征与理论的频散特征进行对比,证明二者非常吻合,验证了Love面波有限差分模拟的精度很高,可以用来研究复杂情形下的Love面波频散特征,并分析了Love面波位移应力等一系列正演特征.