Separating and imaging diffractions in dip domain on the basis of slope analysis*
Kong Xue 1,2, Wang De-Ying ♦3, Li Zhen-Chun 4, Zhang Rui-Xiang 1, and Hu Qiu-Yuan 1
1. Shengli College, China University of Petroleum, Dongying 257061, China.
2. Shandong Provincial Key Laboratory of Depositional Mineralization & Sedimentary Mineral, Shandong University of Science and Technology, Qingdao 266590, China.
3. College of Earth Science and Engineering, Shandong University of Science and Technology, Qingdao 266590, China.
4. School of Geosciences, China University of Petroleum (Hua Dong), Qingdao 266555, China.
Abstract：
Fracture-cave reservoirs in carbonate rocks are characterized by a large difference in fracture and cavity size, and a sharp variation in lithology and velocity, thereby resulting in complex diffraction responses. Some small-scale fractures and caves cause weak diffraction energy and would be obscured by the continuous reflection layer in the imaging section, thereby making them difficult to identify. This paper develops a diffraction wave imaging method in the dip domain, which can improve the resolution of small-scale diffractors in the imaging section. Common imaging gathers (CIGs) in the dip domain are extracted by Gaussian beam migration. In accordance with the geometric differences of the diffraction being quasilinear and the reflection being quasiparabolic in the dip-domain CIGs, we use slope analysis technique to fi lter waves and use Hanning window function to improve the diff raction wave separation level. The diffraction dip-domain CIGs are stacked horizontally to obtain diffraction imaging results. Wavefield separation analysis and numerical modeling results show that the slope analysis method, together with Hanning window filtering, can better suppress noise to obtain the diff raction dip-domain CIGs, thereby improving the clarity of the diff ractors in the diff raction imaging section.
2020, Vol. 17 
