Seismic Reflection Characteristics of Naturally-Induced Subsidence Affecting Transportation

High-resolution seismic reflections have been used effectively to investigate sinkholes formed from the dissolution of a bedded salt unit found throughout most of Central Kansas. Surface subsidence can have devastating effects on transportation structures. Roads, rails, bridges, and pipeliues can even be dramatically affected by minor ground instability. Areas susceptible to surface subsidence can put public safety at risk. Subsurface expressions significantly larger than surface depressions are consistently observed on seismic images recorded over sinkholes in Kansas. Until subsidence reaches the ground surface, failure appears to be controlled by compressional forces evidenced by faults with reverse orientation. Once a surface depression forms or dissolution of the salt slows or stops, subsidence structures are consistent with a tensional stress environment with prevalent normal faults. Detecting areas of rapid subsidence potential, prior to surface failure, is the ultimate goal of any geotechnical survey where the ground surface is susceptible to settling. Seismic reflection images have helped correlate active subsidence to dormant paleofeatures, project horizontal growth of active sinkholes based on subsurface structures, and appraise the risk of catastrophic failure.     

广西福海山地区物探测量结果及其解释

简要介绍了高精度磁测、210 Po法和EH-4电导率成像系统的工作原理。通过对已知矿床剖面试验成果分析解释,发现在铀矿体上方地表存在负磁异常和210 Po异常。把福海山地区高精度磁测和210Po法面积测量结果与已知矿床剖面试验成果进行对比分析,圈出了铀矿化区和断裂构造F1、隐伏断裂F0的分布特征,并采用EH-4电磁测深进行验证。说明利用高精度磁测和210 Po法可以有效地推测出测区构造、断裂带的分布范围,为矿区矿化地段深部找矿工作提供有利的勘查区域范围,为下一步的普查工作提供了可靠的地球物理依据。     

断控层析速度建模方法研究与应用

在复杂断块区域,速度建模及偏移成像是地震资料处理的重要环节,偏移成像的质量依赖于速度模型的准确度.为更好的提升复杂断块区域的速度建模精度,本文提出断层控制层析技术.该技术通过结构张量准确识别和提取断层位置,并建立断层控制矩阵和目标泛函表达式,基于上述方式实现对层析反演迭代过程的约束,最终获得高精度的速度场.为验证上述方法的有效性,应用常规速度层析方法与本文方法进行对比,用二者方法得到的速度分别制作合成地震记录,并与实际钻井数据合成地震记录进行相关,结果证实本文方法的数据和钻井数据的相关性为0.75,而常规层析建模方法的数据和钻井数据的相关性为0.58.结论表明本文方法的速度和真实速度匹配程度高,具有较好的应用效果.

     

多相管流电磁成像测井方法研究

基于油、气与水的导电特性和介电特性差异,提出一种多相管流成像测井方法,可测量并求出油井内多相流体流动的截面图像．通过分析油井内流体中电磁场的特性,提出新的成像测井方法,并用自行研制的环状阵列式测量探头进行实验,验证了方法的可行性．     

用成像测井资料描述碳酸盐岩储集层——以车古20潜山为例

碳酸盐岩、火成岩等复杂性油气藏具有岩性、孔隙空间结构复杂、非均质性强等特点,单纯用常规测井技术很难对这些油气藏进行准确评价,必须借助于成像测井等新技术资料。成像测井不仅能直观地显示各种裂缝、溶洞等地质特征,而且还能定量计算裂缝的各种参数,以及研究孔隙结构。这里详细介绍了成像测井新技术裂缝识别、储层划分、裂缝参数计算、孔洞频谱分析等方法,并利用这些方法描述了车古20潜山碳酸盐岩储集层的裂缝,以及溶蚀孔洞发育特征,识别出了此潜山的储层,还结合其它资料,得出了该潜山油气藏的储层分布规律。     

铁路隧道水热害不良地质体大地电磁场特征研究 ——以川藏铁路茶洛隧道为例

以川藏铁路茶洛隧道水热不良地质体大地电磁场特征为研究对象,利用大地电磁测深多测点-多频点阻抗张量成像分析,分解出电性主轴统计玫瑰图、频率分布云图、测点分布云图及构造维性参数等进行大地线性构造识别,利用精细二维反演技术推测地质结构特征,对不良地质体进行成像,为川藏铁路隧道选线提供地球物理参考。得出结论为：拟建隧道处大地构造二维性强,适宜开展二维大地电磁测深作为隧道水热勘察手段;通过查明研究区构造特征,推测出了研究区热泉群深部地热运移模式机理,且该热害影响茶洛隧道建设的可能性很小,只有在杂马岗-毛垭坝断裂与隧道位置交汇处存在一定规模的水害影响。     

Distribution and population structure of deep‐dwelling red coral in the Northwest Mediterranean

Commercially harvested since ancient times, the highly valuable red coral Corallium rubrum (Linnaeus, 1758) is an octocoral endemic to the Mediterranean Sea and adjacent Eastern Atlantic Ocean, where it occurs on rocky bottoms over a wide bathymetric range. Current knowledge is restricted to its shallow populations (15–50 m depth), with comparably little attention given to the deeper populations (50–200 m) that are nowadays the main target of exploitation. In this study, red coral distribution and population structure were assessed in three historically exploited areas (Amalfi, Ischia Island and Elba Island) in the Tyrrhenian Sea (Western Mediterranean Sea) between 50 and 130 m depth by means of ROV during a cruise carried out in the summer of 2010. Red coral populations showed a maximum patch frequency of 0.20 ± 0.04 SD patches·m^?1 and a density ranging between 28 and 204 colonies·m^?2, with a fairly continuous bathymetric distribution. The highest red coral densities in the investigated areas were found on cliffs and boulders mainly exposed to the east, at the greatest depth, and characterized by medium percentage sediment cover. The study populations contained a high percentage (46% on average) of harvestable colonies (>7 mm basal diameter). Moreover, some colonies with fifth‐order branches were also observed, highlighting the probable older age of some components of these populations. The Ischia population showed the highest colony occupancy, density and size, suggesting a better conservation status than the populations at the other study locations. These results indicate that deep dwelling red coral populations in non‐stressed or less‐harvested areas may diverge from the inverse size‐density relationship previously observed in red coral populations with increasing depth.     

磁共振增强血管造影对肾动脉解剖变异初探?

目的：探讨MR增强血管造影（CE-MRA）显示肾动脉解剖变异的价值。方法：采用回顾性分析213例肾动脉CE-MRA检查图像,包括肾动脉变异的显示情况以及分型。结果：肾动脉变异分别占病例数和肾脏数的30.05％（64/213）和19.72％（84/426）,其中肾动脉过早分支发生率为6.57％（28/426）,副肾动脉变异发生率为13.15％（56/426）。女性肾动脉变异发生率小于男性,同一患者两侧肾动脉变异发生率无显著性差异。常见肾动脉解剖变异类型均有显示。结论：肾动脉的解剖变异可以通过动态增强MR血管造影准确显示。     

Unsupervised ore/waste classification on open-cut mine faces using close-range hyperspectral data

The remote mapping of minerals and discrimination of ore and waste on surfaces are important tasks for geological applications such as those in mining. Such tasks have become possible using ground-based, close-range hyperspectral sensors which can remotely measure the reflectance properties of the environment with high spatial and spectral resolution. However, autonomous mapping of mineral spectra measured on an open-cut mine face remains a challenging problem due to the subtleness of differences in spectral absorption features between mineral and rock classes as well as variability in the illumination of the scene. An additional layer of difficulty arises when there is no annotated data available to train a supervised learning algorithm. A pipeline for unsupervised mapping of spectra on a mine face is proposed which draws from several recent advances in the hyperspectral machine learning literature. The proposed pipeline brings together unsupervised and self-supervised algorithms in a unified system to map minerals on a mine face without the need for human-annotated training data. The pipeline is evaluated with a hyperspectral image dataset of an open-cut mine face comprising mineral ore martite and non-mineralised shale. The combined system is shown to produce a superior map to its constituent algorithms, and the consistency of its mapping capability is demonstrated using data acquired at two different times of day.     

Poststack diffraction imaging using reverse‐time migration

We propose a method for imaging small‐scale diffraction objects in complex environments in which Kirchhoff‐based approaches may fail. The proposed method is based on a separation between the specular reflection and diffraction components of the total wavefield in the migrated surface angle domain. Reverse‐time migration was utilized to produce the common image gathers. This approach provides stable and robust results in cases of complex velocity models. The separation is based on the fact that, in surface angle common image gathers, reflection events are focused at positions that correspond to the apparent dip angle of the reflectors, whereas diffracted events are distributed over a wide range of angles. The high‐resolution radon‐based procedure is used to efficiently separate the reflection and diffraction wavefields. In this study, we consider poststack diffraction imaging. The advantages of working in the poststack domain are its numerical efficiency and the reduced computational time. The numerical results show that the proposed method is able to image diffraction objects in complex environments. The application of the method to a real seismic dataset illustrates the capability of the approach to extract diffractions.