Accurate Seismic Imaging Methodstargeting To The Middle And Depth Reflections In Yingqiong Basin

The oil and gas exploration areas of Yingqiong Basin mainly contain two zones:Yinggehai Basin and Qiongdongnan Basin. The roughness of submarine relief and the complex geological conditions in mid-deep strata, that there are multiple ultra-low velocity layers, abnormal high pressure and stratigraphic vertical fractures,and many other factors cause low signal to noise ratio(SNR) of seismic data in mid-deep strata and great difficulty of accurate velocity modeling and exact structure fidelity imaging. So these factors seriously influence the benefit of exploration in Yinggehai-Qiongdongnan Basin.In order to solve the above exploration problems in Yinggehai-Qiongdongnan Basin, this paper focuses on two aspects: seismic data acquisition and velocity modeling and imaging in complex media. We try to put forward aprocessing procudure which can be applied to actual production and also want to develop and perfect some key techniques in the procedure.So, the core content of this paper includes the following several aspects: first of all, we analyze the key problems encountered in the exploration in Yinggehai-Qiongdongnan Basin and extract the objective that precision imaging aimed at. Then we analyze the geometry according to the requirements of imaging precision, and focus on the illumination in all azimuth observation. We point out the central role of wide-azimuth illumination in velocity analysis and imaging. Next we analyze the characteristics of beam imaging. beam imaging possesses advantages in protecting weak signal, imaging low SNR data and outputting Common Imaging Gather(CIG). In order to meet the requirements of imaging in mid-deep areas ofcomplex media, we develop beam Imaging technique in anisotropic media and attenuation media. And we analyze the effectiveness of absorption and attenuation seismic imaging in the mid-deep area which is saturated with natural gas in Yinggehai.Tomography velocity inversion and modeling in Angle Domain Common Imaging Gathers(ADCIG) is the core technology of our discipline, and thus we analyze the key point of this method in the article. Besides, we propose the technical route of beam tomography velocity inversion and modeling. We also discuss the implementations of a specific method to get a satisfying result in both theoretical and real data.This paper aims to solve the key problem of imaging in the mid-deep zone which CNOOC Zhanjiang Branch encountered in Yinggehai exploration areas. We propose a set of effective processes from seismic acquisition to velocity building and imaging in complex media. Several involved core technologies have been perfected during the process of actual data tests. What’s more, the application of this technology process improves precision of imaging in mid-deep zone, reducing the exploration risks at the same time.