共查询到14条相似文献,搜索用时 79 毫秒
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目前常用的根据记录波形的频率、振幅等特征进行岩溶区探地雷达目标识别的方式具有一定的局限性,为此提出了利用小波能量谱特征进行识别的新方法.通过对岩溶区典型样本进行分析,构造雷达信号各频率成分在各尺度上的能量特征向量,得到样本模型的能量谱,将待识别目标体的能量谱特征与之比对,数据分析和实际验证表明,小波特征能量谱具有直观地显示目标信号不同特征的优点,能有效地对岩溶区探地雷达剖面目标体进行识别. 相似文献
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在探地雷达勘探中,由于受到采样点数与测量速度不匹配、地表不均匀或仪器内外部干扰等因素的影响,容易造成信息不完整,甚至缺失.如何有效重构缺失信号是提高原始GPR数据精度和进行后续高分辨率成像的关键环节.本文提出了一种残差特征提取网络(RFD-U-Net)来针对性处理数据缺失这一问题.其中,RFD采用信息蒸馏网络的方法对缺失数据进行重构,首先使用多个特征提取连接来进行特征学习,然后在残差单元上增加跳跃映射,补充卷积过程中损失的特征信息,最后与轻量网络U-Net相结合,极大程度地缩减了网络冗杂.合成测试数据的对比结果及UQI和SNR两种评价指标的量化分析结果可知,RFD-U-Net获得了最优的重构效果和最佳的计算数值,验证了本文所提方法重构缺失GPR剖面的准确度和优越性.将RFD-U-Net应用于实测数据中,能够较好地重构缺失数据,在细节上突出了有效信号的连续性,并采用自动聚焦技术这一评价指标进行佐证,证明了该方法的实用性. 相似文献
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Multifractal modelling and spectrum analysis: Methods and applications to gamma ray spectrometer data from southwestern Nova Scotia, Canada 总被引:3,自引:0,他引:3
CHENG Qiuming . State Key Lab of Geological Processes Mineral Resources China University of Geosciences Wuhan China . Department of Earth Space Science Engineering Department of Geography York University Keele Street Toronto Ontario MJ P Canada 《中国科学D辑(英文版)》2006,49(3):283-294
Multifractal theory was developed for handling scale invariant fields instead of geometry only[1―4]. From a multifractal point of view, some fractal models, ordinary physical processes and relevant probability distribution types can be considered as special cases of multifractal models which provides new insight into the interrelationships between systems and subjects. For example, the low order moment exponents τ (0), τ (1), τ (2) or τ ″(1) obtained by means of the moment method determi… 相似文献
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鄂尔多斯盆地延长组岩芯分析与测井特征研究表明,相对高自然伽马砂岩具有高长石、高Th、局部高U、K含量变化不大的共同特征,Th、U含量特征与凝灰岩极为相似;相对高自然伽马砂岩具有相对高自然伽马、高声波时差、低电阻率值的测井曲线特征,与凝灰岩测井曲线特征也极其相似;再者,从长6到长4+5油层组的各亚组,凝灰岩层逐渐不发育的同时,伴随相对高自然伽马砂岩发育程度依次增强;上述3项特征预示着延长组相对高自然伽马砂岩可能为同沉积期或较先期沉积的凝灰岩经搬运后作为砂岩组成部分再沉积形成的.四性关系研究表明:(1)依据自然伽马-自然电位曲线重叠图、声波时差-自然电位曲线重叠图,可快速识别相对高自然伽马砂岩;(2)相对高自然伽马砂岩具有相对发育的次生孔隙,非均质性强,一般物性越好,声波时差-自然电位曲线重叠图幅度差越大;(3)计算自然电位-自然电位曲线重叠图的幅度差,反映相对高自然伽马砂岩含油性,幅度差越大,表明其含油性越好. 相似文献
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Airborne gamma ray survey data were used to provide information on potassium, thorium and uranium concentrations in surface soil and rock in arid central Australia. Spatial patterns in these radioelements allow tracing of paths of sediment at catchment scale. Survey elevation data are combined with contour data to produce digital elevation models for terrain analysis, tracing of sediment flow paths and modelling of extreme floods. Gamma ray data show consistent variation with slope, a limited range of drainage areas, and erosion/deposition models derived from the conservation of mass equation. Supply‐limited sediment transport models give a reasonable reproduction of observed radioelement distribution but some elements of the distribution pattern reflect the area inundated by 500–1000 year floods rather than the effects of simple downslope movement. Partial area sediment supply models are derived by downstream accumulation of erosion and deposition rates calculated using the conservation of mass equation with transport laws based on slope alone and stream power. Comparison with observed radioelement patterns suggests that both transport laws apply in different parts of the landscape. Regional‐scale sediment transport models will require a range of models depending on location in the landscape and event frequency. This approach may allow estimation of sediment delivery ratios. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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自然电位、自然伽马测井曲线形态和特征与沉积相带及其储集砂体关系密切,它们对不同岩性地层特征响应十分敏感.利用自然伽马、自然电位同步减小的较大幅度评价识别渗砂层,指示划分水下分流河道主体沉积微相带;利用自然伽马、自然电位减小的幅度差评价识别低渗砂、致密砂层,指示划分水下分流河道堤泛(侧翼)沉积微相带;并以自然电位比自然伽马减小幅度的相对细小差异识别油水层.在安塞油田沿河湾地区长6自然伽马、自然电位曲线划分沉积相带及储层的应用中,建立了自然伽马、自然电位划分储层的下限标准,有效地评价了特低渗透储层沉积微相带及储层类型,提高和扩大了测井曲线的应用及效果. 相似文献
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本文应用单能窄束伽马射线理论建立高分辨率屏蔽自然伽马探测器三维测井响应的数值模拟算法.首先利用单能窄束原理,用稳态扩散方程描述伽马光子密度的空间分布,根据扩散方程基本解、放射源空间分布、探测器位置和屏蔽情况,将屏蔽探测器上的总伽马通量表示成放射性地层中的有效探测区域上的体积分和晶体表面上有效接收面的面积分形式.并根据伽马射线传播路径和探测器屏蔽情况,给出有效探测区域的解析表达式,通过数值积分法计算任意复杂情况下探测器上的自然伽马通量,获得伽马测井响应的3D数值模拟算法.并通过数值模拟结果与模型井数据的对比验证了该算法的有效性.最后通过3D数值模拟算法系统研究考察晶体形状(圆柱形晶体、方形晶体)、晶体长度、仪器在井轴中的位置(居中屏蔽探测器、贴井壁屏蔽探测器)、以及测速等不同情况下自然伽马测井响应,设计出新型高分辨率自然伽马测井仪器. 相似文献
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Spectral gamma ray wireline logging derives the concentrations of potassium, thorium, and uranium of the formation by measuring the gamma ray spectrum under the assumption of secular equilibrium. These measurements were carried out in a number of boreholes drilled by Ocean Drilling Program Leg 193 at the PACMANUS hydrothermal field. Spectral gamma ray logs from several of these holes show intervals of increased radioactivity, associated with high uranium values of up to 60 ppm (Snowcap hydrothermal field) and 25 ppm (Roman Ruins hydrothermal field). Nine samples of hydrothermally altered dacite were analyzed using gamma spectrometry to examine the origin of elevated radioactivity and to test for distortion of secular equilibrium. Core spectrometry indicates that secular equilibrium is distorted. Distortion can be explained by either an uptake of nuclides of the lower part of the 238U decay series, or by removal of 238U or 234Th from the rocks. In all cases wireline uranium logs and core spectrometry do not reflect true uranium concentrations of the formation but uranium is overestimated by a factor of 3–4. At Roman Ruins, uranium values from wireline logging show higher uranium concentrations over large intervals than uranium values from core spectrometry and from published core geochemistry, even when a possible leaching of uranium is taken into account. Wireline logs indicate that depth intervals of increased radioactivity are related to the occurrence of stockwork mineralization. In these depth intervals, core recovery was extremely low. In addition to the distortion of secular equilibrium, low core recovery and preferential loss of softer and more altered material cause a sampling bias between core samples and wireline data and may explain the observed difference in uranium concentrations between core and wireline logs. 相似文献
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In‐situ gamma‐ray spectrometry (GRS) measurements were conducted at 35 sites in Hong Kong where volcanic rocks with varying extent of weathering were exposed. Elemental analyses using X‐ray fluorescence spectrometry and inductively coupled plasma–mass spectrometry were carried out on samples collected from these 35 plus 22 other locations to assess the feasibility of using the GRS method to quantify the extent of weathering. The Parker weathering index, varying within a range of 0·0–0·8 for the samples studied, was used as a geochemically based reference scheme for correlating the gamma‐ray spectrometric results with the extent of weathering. For the former 35 sites, the concentrations of the three major radioelements, K, U and Th, determined by in‐situ GRS were compared to laboratory‐determined values from the samples. The study reveals that no significant change occurs to the contents of the three radioelements during the initial state of weathering. But once the rocks become highly weathered, further progression of weathering is accompanied by a systematic removal of K and an increased dispersion of U and Th. The results show that K content, which is indicative of the extent of weathering, can be retrieved reliably with the gamma‐ray spectrometry technique. The study has given support to the potential use of the downhole spectral gamma method for evaluation of weathering grade and the detection of subsurface clay‐rich levels. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
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元素俘获能谱测井标准谱测量与模拟(英文) 总被引:3,自引:1,他引:2
为了解决目前元素俘获能谱测井解释中,根据原始测量谱难以准确获得各个元素产额的困难,本文建立了一套先进的测量元素俘获伽马能谱实验方法,首次获得了硅、钙和铁等10种元素的标准俘获伽马能谱;并利用蒙托卡罗方法在同样条件下模拟得到了上述10种元素的标准模拟俘获伽马能谱。将这两种方式获得的元素标准俘获伽马能谱与国际原子能机构核数据中心数据进行对比分析,从中确定了可用于实际元素俘获能谱测井解谱计算的硅、钙和铁等10种元素的俘获伽马能谱。这一结果有效解决了元素俘获能谱测井资料处理过程中由原始测量谱到各元素产额转换过程中的关键技术难点,可有效提高元素产额的计算精度。 相似文献
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Johana Brokešová 《Pure and Applied Geophysics》1996,148(3-4):503-538
The seismic wave field, in its high-frequency asymptotic approximation, can be interpolated from a low- to a high-resolution spatial grid of receivers and, possibly, point sources by interpolating the eikonal (travel time) and the amplitude. These quantities can be considered as functions of position only. The travel time and the amplitude are assumed to vary in space only slowly, otherwise the validity conditions of the theory behind would be violated. Relatively coarse spatial sampling is then usually sufficient to obtain their reasonable interpolation. The interpolation is performed in 2-D models of different complexity. The interpolation geometry is either 1-D, 2-D, or 3-D according to the source-receiver distribution. Several interpolation methods are applied: the Fourier interpolation based on the sampling theorem, the linear interpolation, and the interpolation by means of the paraxial approximation. These techniques, based on completely different concepts, are tested by comparing their results with a reference ray-theory solution computed for gathers and grids with fine sampling. The paraxial method holds up as the most efficient and accurate in evaluating travel times from all investigated techniques. However, it is not suitable for approximation of amplitudes, for which the linear interpolation has proved to be universal and accurate enough to provide results acceptable for many seismological applications. 相似文献