【作者】 郭磊；

【导师】 童思友； 刘怀山；

【作者基本信息】 中国海洋大学 ， 地球探测与信息技术， 2010， 硕士

【摘要】 高分辨率地震技术是一种经济有效的勘探技术,同时也是提高勘探地质效果的有效手段之一。我国沿海地区的第四系厚度变化较大,一般为30-450m。在近海区域进行高分辨率多道地震调查,能够获得海底浅部几米至几百米范围内的有效地层信息,这一范围恰好是深层油气勘探的盲区,但是对于核电站、跨海大桥、钻井平台等工程选址项目却有十分重要的研究意义。本论文研究近海浅层区域高分辨率多道地震采集和处理方法,目的是：利用多道地震的优势,开展近海浅层地质调查,获得地层穿透深度更深的剖面；采用先进的地震观测仪器,优化观测方式,实现野外高分辨率地震资料采集,获得高品质的原始数据；应用高分辨率地震数据处理技术,对采集得到的资料进行噪音衰减、多次波压制等处理,获得高信噪比高分辨率的剖面；通过研究最终建立起一套针对近海浅地层区域的高分辨率多道地震采集和处理流程。本论文主要从高分辨率地震的采集和处理方法这两个方面分别进行研究。首先,从影响分辨率的采集因素出发,结合近海工程对浅地层调查的一般要求,选用大能量大功率电火花震源激发、24道小道距数字缆进行接收、小偏移距小排列观测方式进行数据采集,同时利用正演模型模拟对采集参数进行选择论证,最终确定最佳采集方案。其次,在资料处理过程中,针对海洋资料中海底鸣震等干扰比较发育的问题,采用预测反褶积、精细速度分析与Radon变换相结合的方法进行多次波衰减；为获取高精度的地层速度信息,利用精准速度分析方法,并结合速度分析和动校正叠加多次迭代的方法对数据进行处理；为提高资料的信噪比,利用多项式拟合、随机噪音衰减和IF-K滤波等方法,对资料中存在的几种特殊噪音干扰(如岛礁、邻船、井架干扰等)进行压制。通过本论文的研究,形成了一套适用于近海浅地层高分辨率多道地震调查的采集和处理方法。从实际资料的应用效果可以看出,本论文所研究的多道地震采集方法确实可行,且比较经济方便,使用大功率电火花震源激发,避免了气泡效应对有效能量和高频成分的损失,采用24道小道距数字缆直接接收数字信号,提高了数字采集的精度；利用自主研发的高分辨率采集系统进行海上施工,选用合理的观测方式,不仅提高了地层的穿透深度,而且改善了原始资料的分辨率。通过高分辨率处理方法,在一定程度上压制了资料中存在的多次波等主要干扰,极大改善了资料品质,最终获得高信噪比、高分辨率的资料。在数据处理中,通过精细速度分析,获取了较为精确的地层速度信息。相对于常规海上浅层地震勘探技术,论文所研究的高分辨率多道地震方法无论在采集还是处理方面,对资料质量都有很大改善,获得地下地层的速度等信息真实可靠、地质特征更加清楚,利于后续解释、分析。更多还原

【Abstract】 High resolution seismic exploration technology is an economic and effective method in offshore shallow strata survey. Meanwhile, it is an effective measure to improve the geological effects. The thickness of Quaternary has large variation thickness which is generally 30-450m along the coast in China. High resolution multi-channel seismic survey is mainly carried out to get the effective strata information of shallow seabed from a few meters to several hundred meters in offshore, which is just the blind area of deep exploration of oil and gas, but it has very important research meaning for selecting the location of Nuclear Power Plant, Crossing Sea Bridge, Sea Drilling Platform and so on.The thesis studies the high resolution multi-channel shallow seismic data acquisition and processing methods in offshore.The aim of research is to take advantage of multi-channel seismic to get the deeper penetration sections, to obtain the high resolution shallow seismic data acquisition flow for getting the high quality raw data by using advanced institutions and optimized geometry in offshore shallow geological survey, and to acquire the high resolution shallow seismic data processing flow for getting the high resolution and high signal-to-noise ratio(SNR) sections through suppressing some random noises, multiples, analyzing velocity finely and so on.Firstly, in order to obtain the high resolution shallow seismic data acquisition flow in offshore, the thesis studies the main factors that limit seismic resolution and general requirements of shallow strata survey in coastal region.To improve the acquisition quality, it is used that a large energy spark, a 24-channel digital marine seismic streamer with small trace spacing, short offset and minispread observation in offshore operation. Meanwhile, using the forward modeling technology to choose and demonstrate the seismic acquisition parameters.Then the optimal offshore high-resolution shallow seismic acquisition plan is defined. Secondly, it combines the pre-stack and post-stack predictive deconvolution and Radon transform to attenuate seabed reverberations and other multiples in data processing. Using human computer interactive fine velocity analysis method and iterating the velocity analysis and NMO stack to get high precision strata velocity. To eliminate some special noises in offshore shallow seismic data, for example, noise of island, neighbor boat, derrick and so on, it is also used the polynomial fit technique, random noise attenuation and F-K filter for improving the SNR in processing.The results of this dissertation can form a set of multi-channel shallow seismic data acquisition and processing flow in coastal region.A real application result proves that the multi-channel seismic data acquisition is usefulness, feasibility, convenient and economical in marine shallow stratum survey. By using high-power spark and 24-channel digital streamer, it can reduce bubble effect and save available energy and high frequency components of source wavelet, and the accuracy of data collection is highly improved.After high-resolution seismic data acquisition with reasonable geometry, the stratum depth of penetration is greatly enhanced and the quality of raw data is significantly improved. To some extent, multiples and the other major noises are suppressed, the high-SNR high-resolution sections are ultimately achieved through high-resolution data processing method. Meanwhile, fine velocity analysis is used to obtain comparatively accurate layer velocity in data processing. Compared with conventional marine shallow seismic exploration technology, whether in data acquisition or data processing, the high-resolution multi-channel seismic method has greatly improved the quality of data, and gets the more reliable information of strata such as accurate strata velocity. And the obtained geological characteristics of formation are more clear and evident, that is propitious to the subsequent data interpretation and analysis.更多还原