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1.
边界识别技术是位场数据解释中一项基本的工作,现有的边界识别方法多存在边界识别结果发散和不能均衡深浅地质体异常的缺点.目前一些均衡边界识别方法会因正负异常同时存在而引起额外的错误边界或者存在人为主观因素去除错误边界信息的缺点.本文充分利用重力位场张量梯度的多信息成分,提出利用水平方向解析信号及其垂向导数与传统的均衡边界识别方法做结合的方式定义新的探测边界的方法.通过理论模型试验证明新方法同传统方法相比,能够更加清晰、准确的圈定出深浅地质体的边界.最后将新的边界识别方法应用到实测重力异常数据解释中,取得了良好的边界识别结果并能够发现更多的构造细节. 相似文献
2.
边界检测在地球物理位场数据解释中占有重要位置.现有的传统边界识别方法有的不能同时显示不同振幅的异常边界,有的虽然能均衡不同振幅的异常,但识别出来的边界信息中含有一些额外的错误的边界信息,尤其是当测量的异常中同时含有正异常和负异常时.目前已有的去除额外错误边界信息的方法存在着一定的人为主观性.为了解决这些问题,本文定义了加强解析信号倾斜角来进行地质体边界识别.通过模型试验证明了该方法不仅能同时清晰地识别深部和浅部地质体的边界,而且能有效地避免引入一些错误边界信息.最后将该方法应用到四川盆地的重力异常数据中,并取得了良好边界结果. 相似文献
3.
The Erzurum Basin has received more attention in petroleum potential research because of its particularity in geographic and tectonic position. There remains debate on the basement structure of the basin since igneous rocks and faults make the structure and stratigraphy more complicated. We utilize gravity data to understand the structure of the Erzurum Basin. This study describes an edge enhancement technique based on the eigenvalues and determinant obtained from the curvature gravity gradient tensor (CGGT). The main goal of this technique is to delineate structural boundaries in complex geology and tectonic environment using CGGT. The results obtained from theoretical data, with and without Gaussian random noise, have been analyzed in determining the locations of the edges of the vertical-sided prism models. The zero contours of the smallest eigenvalue delineate the spatial location of the edges of the anomalous sources. In addition, 3-D gravity inversion of Bouguer anomalies has been used with purpose to estimate the structure of the substrata to allow modeling of the basement undulation in the Erzurum basin. For this reason, the Parker–Oldenburg algorithm helped to investigate this undulation and to evidence the main linear features. This algorithm reveals presence of basement depths between 3.45 and 9.06 km in the region bounded by NE–SW and E–W trending lineaments. We have also compared the smallest eigenvalue zero contours with the HGM images and Tilt derivative (TDR) of Bouguer anomaly map of the study area. All techniques have agreed closely in detecting the horizontal locations of geological features in the subsurface with good precision. 相似文献
4.
地质体构造边界位置的确定是位场数据解释中的一项重要工作,现有很多基于位场梯度张量数据的边界检测滤波器,但存在识别边界位置模糊且无法均衡深浅地质体异常的缺点.本文定义了位场数据的三维构造张量,并提出基于位场构造张量的边界滤波器.为了同时显示不同振幅异常的边界位置,对新定义的滤波器进行归一化处理.在高阶均衡滤波器的计算中需要计算位场的垂向高阶导数,本文引入一种计算的稳定算法,基于拉普拉斯方程利用位场水平导数求解垂向导数,可减小垂向导数计算中产生的误差.将定义的滤波器应用到合成的重磁数据中证明了新方法相比传统的滤波器能更加清晰、准确地圈定边界位置,而且针对同时含有正负异常的地质情况,可避免产生额外的错误边界.最后将新的滤波器应用到实测的重磁数据的解释中,结果显示基于构造张量的滤波器可更准确清晰地划分出断裂的边界位置,发现更多的构造细节. 相似文献
5.
利用观测数据确定地质体的边界位置是位场数据解译中的一项重要工作,传统的边界识别滤波器通常不能均衡深、浅部的地质体边界,近些年相关研究开始致力于发展均衡边界滤波器.本文基于Theta图法定义了新的边界识别滤波器,详述了滤波器波数域及空间域的主要计算公式,通过模型验证,该滤波器显著压制了Theta图法对深部地质体边界的放大作用,较好地平衡了深部和浅部边界.通过与传统的边界识别滤波器对比,本文定义的滤波器能够清晰且更加收敛地圈定出地质体的水平边界位置.以长江中下游成矿带庐枞矿集区为例,开展了1∶5万重磁数据的处理分析,并结合物性资料进行了讨论,结果表明:重磁数据的检测结果精确刻画了郯庐断裂带的位置;庐枞盆地的磁力数据检测边界整体与盆地的地质边缘一致,明确了边界断裂在深部倾向盆地内部;识别出庐枞盆地外围一系列环形边界,这些边界封闭区域与最新勘探发现的深部岩体及铁铜矿化体相对应,对于指导区域深部找矿工作有着重要的意义. 相似文献
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7.
位场梯度换算在地质体边界检测中有着重要的应用.但传统的梯度算法易受干扰影响,计算稳定性差,且很难在复杂的叠加异常中识别出小型地质体的边界.鉴于此,本文给出了自比值的定义,提出了能够处理高阶导数的位场垂向梯度最佳自比值的边界检测方法,阐述了方法的数学含义和物理意义.模型试验表明,垂向梯度最佳自比值算法不仅计算稳定性强,而且能清晰地检测出传统梯度算法无法检测的模型体边界.在地质条件复杂的鸭绿江盆地的重力异常实例应用中,垂向三阶导数最佳自比值计算结果识别出的构造边界与实际地质体分布有着较好的对应关系,这不但与前人的工作成果互为佐证,而且自比值圈定的负异常分布区能较好地反映出浑江煤田的工作范围. 相似文献
8.
位场全张量梯度数据以其信息量大、含有更高频的信号成分,能更好地描述小的异常特征等优点在地球物理领域中得到广泛应用.边界检测是位场解释中不可缺少的任务,需要新的边界探测器来处理位场梯度张量数据.为了充分利用位场梯度张量数据的多信息成分,本文定义了方向总水平导数和加强方向总水平导数,并利用其定义新的边界检测器.为了能同时显示不同振幅大小异常的边界,本文对其进行了归一化处理.通过模型试验,证明了归一化方法能更加清晰准确地显示浅部和深部的地质体边界信息.最后将该边界检测方法用于加拿大圣乔治湾实际测得全张量重力梯度数据和中国朱日和地区的磁异常数据中,并得到了较好的边界检测结果. 相似文献
9.
针对传统的重磁对应分析在场源区域外趋于高相关度的缺点,本文提出了一种基于相关系数和垂向导数的重磁场源位置及属性识别方法,给出了一个新的重磁场源平面位置及属性判别参数(GMCP),该参数能够有效地缩小重磁场源的识别范围.判别参数GMCP值非零分布范围反映了场源的规模.GMCP值的正负反映了场源属性,当GMCP大于零时为正相关,代表了该区域存在高磁高密度或低磁低密度的重磁同源地质体;当GMCP小于零时为负相关,代表了该区域存在高磁低密度或低磁高密度的重磁同源地质体;GMCP趋于零,则表示无重磁同源地质体.两组不同干扰水平的同源复杂组合模型实验、两组不同源组合模型试验以及南海中央海盆实际重磁数据处理结果均验证了该重磁场源位置及属性识别方法的正确性和有效性. 相似文献
10.
Theta图是利用位场(重磁)数据识别边界的常用方法,其表达式为重磁异常水平变化与垂直变化的比值函数.该方法计算浅源地质体边界的效果较好,而由于深源位场数据在换算过程中会产生趋同效应,在深源地质体识别应用中计算结果不准确,为此,本文提出Theta-Depth法并进行地质体埋深的计算.首先给出直接利用Theta图像进行场源体深度估算的方法,然后推导出基于Theta导数的线性方程来自动估算场源位置参数,本文方法可有效地利用Theta图像的特征为约束条件来提高反演结果的精度.理论模型试验证明本文提出的Theta-Depth法能有效地计算出场源体位置和深度.将该方法应用于满都拉地区实测磁数据的解释,帮助圈定了矿脉的分布. 相似文献
11.
优化算法的选取在很大程度上影响着三维重力反演的计算效率,从而制约着三维重力反演的实用性.在复杂地质构造背景下,不同岩性单元之间可能会发生物性突变,产生尖锐边界.为此,本文提出了一种新的基于柯西分布约束和快速近端目标函数（Fast Proximal Objective Function,FPOF）优化的三维重力反演方法.FPOF优化方法的一个突出特点是在每一步迭代过程中逐一计算剖分网格内的未知密度参数,因此,有较低的计算复杂度和较高的计算效率.此外,目标函数中柯西范数（Cauchy norm）的引入会对反演结果施加稀疏性,有助于产生块状效果.理论模型测试表明,本文方法不仅能产生更加聚焦的反演效果,而且反演所需的时间也比传统的共轭梯度优化方法少.最后将本文方法应用于我国西部某地区实际重力数据,反演结果与已知的地质信息有较好的一致性. 相似文献
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重力反演是恢复地下密度空间分布的有效工具,而选择合理的密度模型约束方法是提升重力反演分辨率和可靠性的关键.常规约束方法大多是从剖分网格空间中的密度模型出发,通过调整光滑或稀疏约束权重来匹配反演目标,但当地质体类型多样、异常分离不准确及网格剖分方案不合理时,模型约束的合理性与灵活性难以得到有效保证.为此,本文提出了一种基于密度模型稀疏表征的重力反演方法.首先假设待反演的密度模型表征为模型特征矩阵和稀疏分解系数的线性组合,之后重新推导了重力反演目标函数,并给出了分解系数的稀疏求解过程.相比现有重力反演方法,用于构建模型特征矩阵的特征模型可包含不同类型地质体的先验几何信息,分解系数的稀疏性保证了待反演目标来自于最典型的地质模式组合.最后,通过模型试验及实际资料验证了基于密度模型稀疏表征的重力反演方法的有效性. 相似文献
13.
Imen Hamdi-Nasr Mohamed Hédi Inoubli Abdelhamid Ben Salem Saïd Tlig Abdelbaki Mansouri 《Geophysical Prospecting》2009,57(4):719-728
Detailed gravity measurements integrated with geological data were computed to constrain the mechanisms that were active during the emplacement of the Triassic evaporite-bearing folds of Jebel Cheid from the salt-dome zone in the Atlassic region. The gravity analysis consists in mapping the contrasting gravity responses: complete Bouguer anomaly, residual anomaly and derivative maps; the main results display a positive amplitude gravity anomaly as the response of Triassic evaporite bodies and important NE–SW-trending features at the boundaries between the Triassic outcrops and their enveloping strata. In contrast with gravity calculations of a salt dome structure usually resulting in negative gravity anomaly models, the Jebel Cheid clearly expresses a positive gravity anomaly; furthermore, this result is supported by synthetic gravity interpretation. 相似文献
14.
基于改进的小子域滤波的重力异常及重力梯度张量边缘增强(英文) 总被引：1，自引：0，他引：1
针对利用重磁资料增强地质体边界在图像中的视觉效果和提高地质解译的准确性问题,提出应用改进的小子域滤波方法对重力异常及重力梯度张量数据进行增强处理。根据滑动窗口子域平均选择原理,探讨了改进的小子域滤波方法在位场异常数据含有高斯白噪声时,不同窗口大小对地质体边界的识别效果及其在具有不同边界延伸方向地质体中的应用效果。模型试验结果表明,利用改进的小子域滤波对重力梯度张量数据进行增强处理,得到的地质体边界形态失真更小,且受滤波窗口大小、噪声以及地质体边界方向的影响较小;对深部场源体,通过增大滤波窗口的方式,可以较好地反映深部场源体的边界。结合黑龙江省虎林盆地重力异常以及计算的重力梯度张量的处理实例表明改进的小子域滤波法较传统的小子域滤波法增强了对断裂水平位置信息的识别。 相似文献
15.
For outcropping bodies an approximate direct interpretation of the associated gravity anomaly is generally obtained with the flat plate formula. Results can be significantly improved if the causative body is approximated by a bell shape instead of a flat plate. A set of parameter curves allows the conversion to depth data. The validity of the method is borne out by synthetic models and by field examples in a Nevada valley with Tertiary and in the Los Angeles Basin. The method provides structural definition more accurate than can be obtained with the flat plate formula, particularly in the case of narrow anomalies. 相似文献
16.
An equivalent layer magnetization model obtained from inversion of long-wavelength satellite magnetic anomaly data indicates a very magnetic source region centered in south central Kentucky. The magnetization maximum nearly coincides with a gravity high elongated north-south and extending into Tennessee. Previous refraction profiles suggest that the source of the gravity anomaly is a large mass of rock occupying much of the crustal thickness. The outline of the source delineated by gravity contours is also discernible in aeromagnetic anomaly patterns. Taken together, the geophysical data suggest a large, localized mass of intracrustal rock which is both dense and very magnetic. A simple magnetization/density model is given which accounts for the gravity and long-wavelength aeromagnetic anomalies due to the body. We interpret it as a mafic plutonic complex, and several lines of evidence are consistent with a rift association. The body is, however, clearly related to the inferred position of the Grenville Front. It is bounded on the north by the fault zones of the 38th Parallel Lineament. The inferred mean magnetization (4 A/m) of the body is large, but not inconsistent with values reported by others for deep crustal bodies associated with long-wavelength magnetic anomalies. Such magnetization levels can be achieved with magnetic mineralogies produced by normal oxidation and metamorphic processes and enhanced by viscous build-up, especially in mafic rocks of alkaline character. 相似文献
17.
Balanced edge detection filters can recognize the edges of the shallow and deep bodies simultaneously, and are commonly used in the edge detection of potential field data. In this paper, we present using the balanced edge detection filters to estimate source locations, and derive two linear equations based on the balanced edge detection filters that can estimate the locations of the source without any priori information about the nature (structural index) of the source. The proposed methods are demonstrated on synthetic gravity anomalies, and the inversion results show that the proposed methods can successfully estimate location parameters of the sources. I also apply the proposed methods to real magnetic data, and the inversion results estimated by the proposed methods are consistent with the results estimated by the other similar method. 相似文献
18.
Elizangela S. Amaral Mota Walter E. Medeiros Roberto G. Oliveira 《Geophysical Prospecting》2020,68(7):2271-2291
Severe limitations of the standard Euler deconvolution to outline source shapes have been pointed out. However, Euler deconvolution has been widely employed on field data to outline interfaces, as faults and thrust zones. We investigate the limitations of the 3D Euler deconvolution–derived estimates of source dip and volume with the use of reduced-to-the-pole synthetic and field anomalies. The synthetic anomalies are generated by two types of source bodies: (1) uniformly magnetized prisms, presenting either smooth or rough interfaces, and (2) bodies presenting smooth delimiting interfaces but strong internal variation of magnetization intensity. The dip of the first type of body might be estimated from the Euler deconvolution solution cluster if the ratio between the depth to the top and vertical extent is relatively high (>1/4). For the second type of body, besides dip, the source volume can be approximately delimited from the solution cluster envelope, regardless of the referred ratio. We apply Euler deconvolution to two field anomalies which are caused by a curved-shape thrust zone and by a banded iron formation. These anomalies are chosen because they share characteristics with the two types of synthetic bodies. For the thrust zone, the obtained Euler deconvolution solutions show spatial distribution allowing to estimate a source dip that is consistent with the surface geology data, even if the above-mentioned ratio is much less than 1/4. Thus, there are other factors, such as a heterogeneous magnetization, which might be controlling the vertical spreading of the Euler deconvolution solutions in the thrust zone. On the other hand, for the iron-ore formation, the solution cluster spreads out occupying a volume, in accordance with the results obtained with the synthetic sources having internal variation of magnetization intensity. As conclusion, although Euler deconvolution–derived solutions cannot offer accurate estimates of source shapes, they might provide a sufficient degree of reliability in the initial estimates of the source dip and volume, which may be useful in a later phase of more accurate modelling. 相似文献
19.
针对重力异常反演的现状,采用矩形单元体网格剖分的二度半体组合模型,模拟任意的多层密度界面或形体,实现了重力正演.该建模方法适应性强,适合于实际工作中常见的密度横向变化的复杂模型.使用改进的全局寻优的快速模拟退火算法,对重力异常进行反演,结合这种灵活的密度建模方法,反演过程中只需要反演各矩形单元体的密度参数,即可同时得到地质体的界面或形态以及密度值分布.通过复杂界面和形体的模型试验,证明了方法的效果.在江苏下扬子地质构造复杂区的实际应用说明,在地震等先验信息约束下,该重力反演方法提高了反演精度并减少了多解性,可有效解决古生界泥盆系-志留系目的层分布等地质问题. 相似文献
20.
图像增强技术在重磁图像中的应用 总被引：2，自引：0，他引：2
本文综述了图像增强技术在位场数据中的应用现状，并介绍了两种改进的图像增强技术，用于增强重磁图像特征。一种方法借鉴了直方图平滑化的思想，应用于位场彩色影像的色谱的自动确定。该方法的应用能够使色彩合理地配置，从而保证了图像的视觉效果和分辨率。另一种方法基于改进的Radon变化和梯度计算，用于重磁图像中线性特征的检测和增强。该方法能在变化域中突出显示线性特征，从而有利于线性特征的检测和增强。通过对简单图像和实际资料的应用，表明了两种方法在增强特征中的有效性。 相似文献