【作者】 郗来涛；

【导师】 刘怀山；

【作者基本信息】 中国海洋大学 ， 地球探测与信息技术， 2011， 硕士

【摘要】 高分辨率地震勘探目前已广泛应用于近海地质环境调查中,传统的单道浅剖勘探方式在分辨率上已达不到精度要求,特别是对一些老油田进行二次勘探。对于海上工程建设,如海上钻井平台、海底隧道、跨海大桥等,都需要对地下地质构造做出精确的定量分析,包括地层厚度、深度的精确计算和小构造、小断层、薄层的发现与精确描述等,这些都是高分辨率地震勘探的要求。本论文所述的高分辨率多道地震勘探就是把陆上勘探中采用的多次覆盖技术应用到海上地震勘探中,不仅能达到高分辨率勘探的要求,而且具有一定的经济和环保效益。本论文是以南海某区多道地震资料为研究对象,首先明确了高分辨率的定义,高分辨率勘探所获得的地震资料拥有更多的地震反射波同相轴,波组特征明显,有相当高的信噪比和保真度,满足勘探目的层的需要,这也是对本次采集处理后的多道地震资料质量鉴定的依据。与传统单道地震勘探相比,多道地震勘探的优势明显,采用高频、高能量震源,利用多道、小道距采集方法,得到地震资料本身就具有高分辨率的优势,处理过程中利用多种方法相结合的方式衰减去除海上地震资料中的特殊干扰波,以及最明显的多次波干扰。解释过程中首先要对处理的地震资料做质量评价,这是高分辨率多道地震解释的前提。从频带宽度分辨率上分析,这次采集到的多道地震资料有效频带大约是0-1000Hz,根据地震可识别的最薄地层厚度为1/4波长可计算出理想分辨率可达0.4m,满足高分辨率的要求。对海区地质背景描述是解释过程中的必要环节,能在整体上把握该区的地质构造特点。研究区位于南海北部大陆边缘,是一个兼有陆相与海相特点的具有断陷双重结构的盆地,伴随南海的形成与扩张,断裂十分发育,中生、新生代时期岩浆活动频繁,地质构造十分复杂。利用大型工作站进行资料建库,实现潮改,精确进行炮点归位,由于本次研究钻井资料有限,利用地震叠加速度转换层速度,完成了层位深度图。通过对研究区地貌特征、构造演化及地层特征的了解,利用工作站对多道地震数据体进行了资料解释,完成了T₀、T₁、T₂¹、T₂²、T₂³、T₂⁴、T₂⁵、T₃、T_g等九层层位标定及断裂系统组合图,对反射界面深度及沉积厚度进行了详细描述,确定了基岩及其分布特征。通过对这次多道地震资料的解释,识别了该区存在的古河道、低速屏蔽层等特殊地质体,综合利用单道地震资料分析了低速屏蔽层的成分,并最终揭示了该区存在的滑坡、崩塌、泥底辟等地质灾害。最后形成了一套近海高分辨率多道地震勘探解释流程。更多还原

【Abstract】 High-resolution seismic exploration has been widely used in offshore geological survey.The traditional way of single-channel shallow exploration on resolution has not reached the accuracy, especially for some old oil fields for the second exploration. Marine construction projects, such as offshore drilling platforms, tunnel, bridge, etc., we need to make an accurate quantitative analysis for underground geological structures, including accurate calculation for layer thickness,depth,and precise description discovery for small faults, thin layers. These are the requirements of high- resolution seismic exploration. Described in this paper, multi-channel high-resolution seismic exploration is to use the multiple cover techniques to marine seismic exploration, not only has achieved high-resolution exploration requirements,but has certain economic and environmental benefits.This paper is depended on a district of the South China Sea to study the multi-channel seismic data.First, expliciting the definition of high-resolution, seismic data acquired by high-resolution exploration has more seismic reflection phase axis and obvious characteristics of waves,with very high signal to noise ratio and fidelity to meet the needs of exploration targets. This is also basis for identification of seismic data quality after the acquisition and processing of this multi-channel. Compared to traditional single-channel seismic, multi-channel seismic exploration has obvious advantages. The use of high frequency, high-energy source, multi-channel, trail from the collection methods, so the seismic data itself has a high score rate of the advantages. A variety of methods are used to remove the combination of attenuation in marine seismic data, special the most obvious multiple wave interference.Before the interpretation,seismic data quality assessment must to be done , which is the premise of high-resolution multi-channel seismic interpretation.From the resolution of the band width analysis, the collected multi-channel seismic data effective band is about 0-1000Hz, under the thinnest identifiable seismic stratigraphic thickness of 1 / 4 wavelength to calculate the ideal resolution up to 0.4m, meeting the high resolution requirements. Description of the sea geological background is a essential part of the interpretation process, which can grasp the overall features of the area’s geological structure. Study area is located in the northern South China Sea continental margin, which both have marine and continent phase characteristics and therift basin dual structure. With the formation and expansion of the South China Sea, faults are well developed and magmatic act frequently during cenozoic,so the geological structure is very complicated.With the use of large workstation to build database to achieve tidal change,and the shot homing precisely. As the limited drilling data in this study, stack velocity is used to convert seismic velocity and completed layer depth map. by studying geomorphological features,structural evolution of the area, and stratigraphic features of the understanding, using workstations for multi-channel seismic data for the data interpretation, completed the T₀、T₁、T₂¹、T₂²、T₂³、T₂⁴、T₂⁵、T₃、T_g and other nine calibration and fault system layer combination chart. The depth and sediment thickness of the reflecting interface is described in detail to determine the bedrock and its distribution. Through this multi-channel seismic data interpretation, the existence of ancient river,low-speed special geological shield are identified.With single-channel seismic data to analyse components of low speed shield, and eventually revealed the existence of the landslides, avalanches, mud diapirism and other geological disasters. A high-resolution multi-channel seismic exploration of offshore interpretation process is formed finally.更多还原