数据干扰对重磁下延成像的影响研究
1. 中国石油勘探开发研究院, 北京 100083
2. 中国石油大学 (华东), 地球科学与技术学院, 山东青岛 266580
| 摘 要： | 重磁位场逐层优化截频及归一化下延是基于格林等效层位场叠加原理及逐层优化截频滤波建立的一种新的下延成像方法。由于实测数据中总是存在一定的干扰，通过建立单一球体和多层块体的重力模型数据，对不同干扰强度、不同测网密度、不同异常强度的情况进行了下延成像试验。对比表明，不同测网密度和强度的数据干扰主要影响下延1-2个点距深度；但干扰过大或网度过小时，下延成像会出现能量发散和虚假异常现象；增加深层场源物性差异可以增大异常强度，提高数据的信噪比，有利于提高下延成像精度和分辨率。通过川西南实测重磁数据下延成像试验，确认数据干扰影响下延深度主要在1-2个点距，中深部受观测误差影响较小。若原始数据干扰强度较大，建议先进行数据滤波后，再实施逐层优化截频下延成像；若原始数据干扰强度不太大，可直接应用逐层优化截频下延成像，但不建议对下延深度小于2个点距的下延成像结果进行定性和定量解释。 |
| 关 键 词： | 下延成像; 格林等效层; 随机干扰; 干扰强度; 测网密度; 异常强度 |
| DOI： | 10.57237/j.earth.2023.01.001 |
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收稿日期: 2023-06-08
接受日期: 2023-07-14
在线出版日期: 2023-07-24
Study of Noise Affect on Downward Continuation of Gravity and Magnetic Data
1. PetroChina Institute of Petroleum Exploration and Development, Beijing 100083, China
2. Institute of Geosicence and Technology, China University of Petroleum (East China), Qingdao 266580, China
| Abstract: | Based on the superposition principle for potential field of Green's equivalent layers and frequency cutoff filtering by successive layer optimization, a new imaging method of normalized downward continuation of gravity and magnetic data by successive layer optimization (NDCSLO) is developed. Owing to noise interference is unavoidable in field gravity and magnetic data, the affect of noise interference is studied by NDCSLO tests with sphere and slab model data of different noise intensity, measurement grid spacing and anomaly strength. Ii is shown that the most affected interval is the first 1-2 grid spacing of continuation depth. Too small or big grid spacing will result in field energy dissipation and spurious imaging. With increasing source physical property and thus increasing anomaly strength, the signal-noise ratio will be enhanced and benefit improving the resolving power and accuracy of the downward continuation imaging. From NDCSLO test of field gravity and magnetic data in Southwest Sichuan, it is verified that the affect of measurement error is mainly on the first 2km of the continuation depth, and the middle to deep continuation imaging is less influenced. Therefore, it is suggested that if the field data is apparently affected by noise disturbance, a priori noise filtering be used before NDCSLO; otherwise the NDCSLO can be utilized directly, although the continuation imaging of less than the first 2km depth is not recommended to interpret qualitatively or quantitatively. |
| Keywords: | Downward Continuation Imaging; Green's Equivalent Layer; Random Disturbance; Noise Intensity; Grid Spacing; Anomaly Strength |
参考文献
| [1] | 安玉林, 管志宁. 1985. 滤除高频干扰的正则化稳定因子. 物化探计算技术. 7 (1): 13-23. |
| [2] | 程方道, 黄国祥. 重磁位场波谱理论及其应用. 长沙: 中南工业大学出版社, 1987. |
| [3] | 刘东甲等, 2009. 位场向下延拓的波数域迭代法及其收敛性. 2009, 52 (6): 1599-1605. |
| [4] | 王谦身. 重力学. 地震出版社, 北京: 2003. |
| [5] | 王纯, 张研, 文百红. 一种基于重力数据向下延拓的成像方法和装置 (CN107678068A), 2018. |
| [6] | 文百红, 杨辉, 张研. 2008. 双重正则化下延方法及其应用. 重磁数据处理解释应用研讨会论文集 (2008年4月15-18日, 浙江, 杭州). 55-57. |
| [7] | 文百红, 杨辉, 张连群等. 2020. 重磁优化下延成像深部物性结构预测. 2020年中国地球科学联合年会 (2020.10.18-21, 重庆). 6048-6051. |
| [8] | 文百红, 胡庆辉, 张连群. 2021. 地质体形状对逐层优化正则化下延成像的影响研究. 物探与化探, 45 (6): 1553-1558. |
| [9] | 文百红, 杨辉, 张连群. 盆地深部结构重磁位场下延成像应用——以四川盆地为例.见《胡建义院士文集》. 北京: 石油工业出版社, 2023. 430-438. |
| [10] | 徐凯军, 刘展, 张旺. 一种基于深度变化的三维重力位场正则化下延方法及应用 (CN 103869376A). 2014. |
| [11] | 徐世浙, 2006a. 位场延拓的积分-迭代法. 地球物理学报, 49 (4): 1176-1182. |
| [12] | 徐世浙, 2006b. 位场大深度向下延拓. 中国地质学会2006勘探地球物理学术交流会 (2006.9.25. 乌鲁木齐), 29-31. |
| [13] | 徐世浙, 余海龙, 李海侠, 田钢, 杨金玉. 2009. 基于位场分离与延拓的视密度反演. 地球物理学报, 52 (6): 1592-1598. |
| [14] | 杨辉, 胡祖志, 文百红等编著. 深层重磁电联合反演方法与应用. 北京: 石油工业出版社, 2022. |
| [15] | 于波等, 2009. 噪声对磁场向下延拓迭代法的计算误差影响分析. 2009, 52 (8): 2182-2188. |
| [16] | Pawlowski R. S., 1994. Green's equivalent-layer concept in gravity band-pass filter design. Geophysics, 59 (1): 69-76. |
| [17] | M. Fedi and G. Florio. 2002. A stable downward continuation by using the ISVD method. Geophys. J. Int. 151, 146-156. |
| [18] | Li JP., Zhang YT., Fan HB. et al. 2020. A stable regularization method of downward continuation of potential field. Studia Geophysica et Geodaetica, 64 (2020): 391-406. |
