RESEARCH ON TIME-DISTANCE INTERPRETATION OF MULTIPLES AND GHOSTS BASED ON MARINE SEISMIC DATA |
| |
| Authors: | ZHI Ming HAO Chong-tao YAO Chen YU Guang-ming CAI Ming-gang |
| |
| Institution: | 1. State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China;
2. China Earthquake Networks Center, Beijing 100045, China;
3. Institute of Multi-component Seismic Technology, Beijing 100029, China |
| |
| Abstract: | Currently, the study on the active fault in the land areas is relatively mature, while there is still lack of detection and research on active faults in the sea areas. Marine exploration, which is different from land areas, has a prominent problem due to the existence of strong reflecting interfaces such as water surface and seafloor in the sea, thus the recording is often accompanied by interference of multiples on seafloor reflections. In addition, because of the characteristics of marine seismic exploration, the source exciting in the water and the geophone receiving in the water, ghost wave usually can be recorded simultaneously during the reflected wave propagation. This phenomenon makes it difficult to distinguish the effective waves and the noise, and has always plagued the data and seriously affects the quality of records. In the offshore and other regions of complex structures, such as inclined interfaces, it is difficult to eliminate the interference of multiples accurately by traditional multiples suppression methods, which are based on the horizontal interface assumption. This paper combines the sea area seismic data and its acquisition method, uses simplified model to simulate the multiples based on the time-distance analysis of multiples and their ghost wave in inclined interface. The time-distance characteristics of the multiples and their ghost waves from different interfaces(including the inclined interface)are obtained, and they are consistent with the actual records. The multiples time-distance simulation can help to distinguish the causes of reflected waves, summarize the multiple-wave time-distance characteristics from different interfaces(including inclined interfaces), and analyze the relationship between the characteristics of multiple waves and primary waves. In particular, this simulation has a significant effect on characterizing the internal multiples that are difficult to identify due to inconspicuous periodicity and the multiples of the inclined interface which present the phenomenon that the vertex of the time-distance curve is shifted. On this basis, relying on the time-distance analysis of ghost wave, we analyze the travel time difference characteristics between reflected waves and their accompanying ghost waves. The differences of the travel time characteristics of different orders ghost wave and reflected wave are summarized and the symmetry of the travel time difference between inclined interface and horizontal interface of ghost waves and reflected waves is analyzed. We simulate the distraction of the ghost wave event with the event of the reflected wave and analyze the influence of the ghost wave on the sea area seismic records. These results can improve the practical interpretation of seismic data. At last, the time-distance information is used to synthesize sea area seismic records, which can help us carry out the effective data processing and understand the characteristics of the time-distance and velocity of multiples in different interfaces and the layer artifact caused by multiples. This study combines the time-distance simulation of multiples and their ghost wave with conventional seismic data processing to analyze the pre-stack and post-stack features of multiple waves and their ghost waves in the seismic records of the sea area. The results of this study are conducive to the effective identification of multiples in seismic records in the sea, provide a theoretical basis for multi-wave suppression and prediction, and may facilitate the future study of sea-area seismic activity detection. |
| |
| Keywords: | sea area multiples ghost waves time-distance simulation data interpretation |
|
| 点击此处可从《地震地质》浏览原始摘要信息 |
| 点击此处可从《地震地质》下载免费的PDF全文 |
|
