Seismic Acquisition Technique Research On Southwest Qaidam Basin

The research area is located at the Southwestern Qaidam Basin in Qinghai Province, and there are complicated topography and various types of surface, including mountains, swamps, lakes, desert, etc. Owing to quickly change of near-surface lithology and structure, poor data quality, such as very low signal to noise ratio, is normal in raw seismic data. Complicated subsurface structure and those developed fault with crisscross make the imaging difficult. With the deepening of oil exploration in the field, seismic data obtained in the past cannot meet the current needs of oil exploration and exploitation, due to old seismic acquisition techniques and equipments.According to the special geological conditions in the southwest Qaidam basin, this paper focuses on the study of seismic acquisition technology for improving the quality of seismic data, and getting some new results or ideas. In the geometry design, the idea based on pre-stack migration is first introduced to the seismic exploration in the Qaidam Basin. Combined the analysis of CRP folds with wave equation modeling and illumination analysis, this method improves the 3D geometry design based on pre-stack migration and optimization process. Probing the relationship between improving the single shot quality and increasing source density will contributed to improving the data of pre-stack migration in Kunlun Mountain. And it was served as analyzing the influence of receiver density and source density on noise attenuation of the geometry. In the near-surface investigations, this study focuses on the surveying of the thick wind-built desert area and the crystalline salt area, which provides the basis for selecting the shot method and computing static correction. Mainly based on their judgments of the imaging results for the base of Quaternary, first-break refraction static correction constrained by the correct model is proved a effective method in computing the statics. In dynamite shooting, the good shooting lithology and its ability of noise attenuation are key considerations to improving the seismic data quality. In receiving, it had been done for comparing the effect of seismic data with different types of geophones, different group geometry and different group interval. The coupling effect of the special geophones embedded tools is improved as well.Having been research seismic acquisition in deep, a set of higher resolution and high-precision data acquisition methods is formed for effectively guiding the 3D seismic exploration in southwest Qaidam basin. And this method is effective in the practice. This study has put emphasis on the key role of "three bottom interface" in improving seismic data quality of desert area, which are the wet sand bottom boundary layer, the sand bottom interface and the bottom of Quaternary interface. The implementation of these technologies and methods effectively meet the current exploration, and the seismic data contributed to find Kunbei oilfield.