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| 复杂地表条件下中深层构造精细成像方法研究及应用 | |
| 其他题名 | Research on Theory and Application of Imaging Methods for Deep Structure under Complex Surface Conditions |
| 徐锦承 | |
| 出版年 | 2015 |
| 学位类型 | 博士 |
| 导师 | 张剑锋 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 近年来，我国油气勘探重心已经由陆上转移到近海，由东部平原转移到中西部山地，油气勘探面临的最大困难往往来自复杂地表，包括滨海滩涂、陡峭山前带、起伏大沙漠、沟壑黄土塬等。由于受制于复杂地表等实际条件限制，这些地区的勘探程度往往较低，比如川西北地区、准格尔盆地南缘等，目前主要还处在构造勘探阶段，因此也是未来油气勘探最有潜力的地区。复杂地表条件下的地震成像是勘探开发这一巨大油气潜力的关键技术，具有重要的研究价值和实际意义。论文以基于波动方程的广义叠前时间偏移为基础，结合等效参数、近地表吸收补偿、成像道集提取剩余静校正、倾角域稳相偏移以及高性能计算等方面展开研究，取得了以下进展： 1. 论文首先针对地表起伏大，有高速层出露这类静校正难题，发展了双参数的复杂地表采集资料的直接叠前时间偏移方法，即在基准面上下都用等效速度参数来描述地震波场传播，避免了常规静校正关于近地表波场垂直出入射的假设。复杂地表采集资料的直接叠前时间偏移方法比叠前数据进行静校正后再偏移有更好的成像效果；同时，可以自主更新偏移速度，避免了复杂地表条件下速度建模的巨大困难。 2. 针对近地表吸收严重的地区，例如黄土塬、沙漠等，通过在叠前时间偏移过程中引入近地表等效 补偿近地表吸收的影响，从而提高整体成像分辨率。考虑到实际近地表 场一般比较难以得到，发展了基于谱比法的近地表等效 拾取方法。 3. 针对陆上地震资料处理的静校正问题（通常偏移后的短波长剩余时差导致信噪比和分辨率降低），提出了一种基于偏移成像道集的地表一致性剩余静校正方法。将剩余静校正量求取由叠前的CMP道集推进到偏移后的偏移成像道集，避免了复杂情况下同相轴归位不准确导致的剩余时差拾取误差。 4. 针对山前带等高陡构造成像信噪比低的问题，发展了倾角域稳相偏移方法，实现了基于涅尔耳带叠加的偏移成像，可大幅压制偏移噪音，得到更高信噪比的共反射点偏移道集和偏移图像。相比基于数据域菲涅尔带的共反射面元叠加（CRS）技术，避免了确定曲率半径的困难，同时能更好的保护断层及断点成像。 5. 针对三维倾角域稳相偏移计算量大的问题，使用图形处理器（Graphic Processing Unit，简称GPU）实现了可处理大规模实际资料的GPU三维稳相叠前时间偏移以及倾角道集菲涅耳带自动拾取软件模块。基于CPU/GPU的协同并行高性能计算得到了将近60倍的加速比。 |
| 英文摘要 | In recent years, our focus on oil and gas exploration had shifted from onshore to offshore, from the eastern plains to the western mountains. The biggest difficulty our country facing on the oil and gas exploration often comes from the complexity of the surface, including the coastal beaches, steep foothills, undulating desert, gullies of the loess tableland and similar complex areas. Since the actual conditions are subject to complex surface and other restrictions, the extent of exploration in these areas always tend to be lower, such as northwestern Sicuan and the southern edge of Junggar Basin. There are still in the stage of structure exploration. Therefore, these regions are the most potential oil and gas exploration areas in the future. Seismic imaging under complex surface conditions is the key technology to exploration and development of this huge potential oil and gas. It has important research and practical values. This dissertation based on generalized wave equation pre-stack time migration, combined with equivalent parameters, the near-surface absorption compensation, residual statics extracted from migrated gathers, stationary phase migration in dip angle domain and the study of high-performance computing. It achieved the following progress: 1. Firstly, to the difficulty statics problem in large topography and high-speed layer exposed areas, we presented a scheme called directly pre-stack time migration method under complex surface based on two equivalent parameters, which used two effective velocity parameters to describe wave propagation through inhomogeneous media above and below a chosen floating datum to do migration from topography surface, and could avoid the hypothesis of the conventional static correction that in the near-surface the wave field perpendicular to shoot in and out. Directly pre-stack time migration to seismic data collection from complex surface could gain better imaging results than conventional processing flows based on static correction. At the same time, it can independently update migration velocity, avoiding tremendous difficulties of velocity modeling on complex surface conditions. 2. For the serious near-surface absorption areas, such as the Loess Plateau, desert, etc., through the introduction of near-surface equivalent in the process of pre-stack time migration to compensate for the effects of near-surface absorption, thereby enhancing the overall image resolution. Taking into account the actual near-surface field is generally very difficult to get, based on spectral ratio method we developed an approach of picking the near-surface equivalent . 3. For statics problem of onshore seismic data (usually short-wavelength shift of the remaining time difference leading to reduced SNR (signal to noise ratio) and resolution), we presented a surface consistent residual statics method based on migration imaging gathers. The residual statics strike propelled by CMP (common middle point) gathers to migrated image gathers, avoiding the error originated from the erroneous picking for the reflections that do not exhibit hyperbolic events in CMP gathers. 4. For the steep structural imaging like foothills with low SNR, we presented a stationary phase migration method in dip angle domain, which achieved the migration imaging in the Fresnel zone. It can significantly suppress migration noise, and get higher SNR of CRP (common reflection point) gathers and migration images. Compared to the CRS (common reflection surface) technology that based on Fresnel zone in data domain, it avoids the difficulty of determining the radius of curvature, and can better protect the faults and break point imaging. 5. For the three-dimensional stationary phase migration in dip angle domain of computationally intensive problem, we had used the graphics processor (Graphic Processing Unit, referred to as the GPU) to achieve accelerating stationary phase time migration that could process large-scale field seismic dat |
| 中文关键词 | 复杂地表 ; 直接叠前时间偏移 ; 剩余静校正 ; 近地表吸收补偿 ; 稳相偏移 |
| 英文关键词 | Complex surface Topography pre-stack time migration Residual static corrections Compensation for near surface absorption Stationary phase migration |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 固体地球物理学 |
| 来源机构 | 中国科学院地质与地球物理研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287503 |
| 推荐引用方式 GB/T 7714 | 徐锦承. 复杂地表条件下中深层构造精细成像方法研究及应用[D]. 中国科学院大学,2015. |
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