Diffraction separation method in the prestack common virtual source gather
YANG Chengzeng1, ZHANG Xuantang1, SHENG Tongjie2, LI Xiaowei1, MA Yunli1, LIU Tao3
1. Exploration and Development Research Institute, SINOPEC North China Peptroleum Bureau, Zhengzhou, Henan 466100, China; 2. School of Geosciences & Surveying Enginee-ring, China University of Mining & Technology-Beijing, Beijing 100083, China; 3. SINOPEC Petroleum Exploration and Production Research Institute, Beijing 100083, China
Abstract：Diffractions carry high-resolution information on underground small-scale heterogeneous geolo-gical bodies, which are of great significance to the recognition of karst reservoirs. The diffractions with weak energy can be easily masked by the reflected wave field,which results in many problems such as unclear migration imaging as well as poor fine-grained recognition and difficult characterization of small-scale anomalies. The traditional diffraction separation method confronts serious energy loss of deep diffractions and difficult separation when diffractions intersect with or are tangential to the reflected wave field. To solve the above problems,we propose a prestack diffraction separation method. Specifically,by the common virtual source transformation,the common shot gather is converted into a common virtual source gather,on which the migration,reflected wave removal,and demigration are performed. Then,the diffraction field of the common shot gather is obtained by inverse transformation of the common virtual source. The application of the numerical model and field data reveals that the method can effectively suppress the reflected waves, keep the energy of diffractions,and improve the recognition accuracy of the small-scale geological bodies on the imaging section.
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