基于频域多尺度全波形反演的海洋水合物地层速度结构与衰减特征研究-以WR313地区为例

海洋水合物研究进入勘探开发并重阶段，已发现的大量水合物藏具有非均质性，获取精细的储层速度、地震波衰减等物性参数对水合物的勘探和开发方案设计意义重大。由常规速度分析和AVO反演建立的速度结构不够精细，而已应用于水合物研究的波形反演算法多受限于层状一维模型，不能解决水合物非均质性问题。当前对水合物地层衰减的研究相对较少。本研究选择墨西哥湾WR313水合物高富集区为靶区，利用OBS和多道地震数据，联合走时反演与深度偏移，建立初始速度模型和深度域剖面; 将频率域多尺度全波形反演算法应用于OBS数据，获取精细的速度结构；以零衰减为初始模型，使用全波形反演建立衰减模型。综合深度剖面、速度结构和衰减模型及钻测井资料，分析高富集度水合物储层特性和地层物性特征。该研究拟提取的速度和衰减信息分辨率可达波长数量级，更好地解决储层非均质问题，为水合物勘探开发方案设计提供参数支持，也为国内水研究研究提供有益借鉴。

The research of marine gas hydrate has developed to the stages of emphasizing both exploration and exploitation, and a large number of gas hydrate occurrences show heterogeneities. Therefore, it’s of importance to obtain accurate velocity structure and seismic attenuation model of hydrate reservoir for hydrate exploration and exploitation strategy designing. The velocity structure obtained from conventional velocity analysis and AVO inversion is not fine adequately. The full waveform inversion methods applied to gas hydrate study are mostly confined to one dimension, which cannot resolve the problem of heterogenetic hydrate distribution. Now there are not many researches on seismic attenuation of gas hydrate reservoirs. This project targets the concentrated gas hydrate zone WR313 of Gulf of Mexico. OBS and MCS data will be used to obtain initial velocity model and seismic profile in depth domain based on the combination of traveltime inversion and depth migration. Muti-scale full waveform inversion in frequency domain will be applied to OBS data to build accurate velocity model. Assuming zero initial attenuation model, full waveform inversion will be used to establish seismic attenuation model. Integrating seismic profile in depth domain, accurate velocity structure and seismic attenuation model, the characteristics of concentrated gas hydrate reservoirs and the physical properties of hydrate-bearing sediments will be studied. The resolution of velocity and attenuation model can reach the wavelength order, which could resolve the heterogeneity of gas hydrate distribution, provide parameters for gas hydrate exploration and exploitation strategy designing, and also provide useful reference for gas hydrate research in China.