Extraction of P- and S-wave angle-domain common-image gathers based on fi rst-order velocity-dilatation-rotation equations*
Li Kai-Rui 1,2,3 and He Bing-Shou 1,2,3
1. Ocean University of China, Qingdao 266100, China.
2. Evaluation and Detection Technology Laboratory of Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China.
3. Key Laboratory of Submarine Geosciences and Prospecting Techniques, Ministry of Education, Qingdao 266100, China.
Abstract：
Accuracy of angle-domain common-image gathers (ADCIGs) is the key to multiwave AVA inversion and migration velocity analysis, and of which Poynting vectors of pure P- and S-wave are the decisive factors in obtaining multi-component seismic data ADCIGs. A Poynting vector can be obtained from conventional velocity-stress elastic wave equations, but it focused on the propagation direction of mixed P- and S-wave fields, and neither on the propagation direction of the P-wave nor the direction of the S-wave. The Poynting vectors of pure P- or pure S-wave can be calculated from first-order velocity-dilatation-rotation equations. This study presents a method of extracting ADCIGs based on first order velocitydilatation-rotation elastic wave equations reverse-time migration algorithm. The method is as follows: calculating the pure P-wave Poynting vector of source and receiver wavefields by multiplication of P-wave particle-velocity vector and dilatation scalar, calculating the pure S-wave Poynting vector by vector multiplying S-wave particle-velocity vector and rotation vector, selecting the Poynting vector at the time of maximum P-wave energy of source wavefield as the propagation direction of incident P-wave, and obtaining the reflected P-wave (or converted S-wave) propagation direction of the receiver wavefield by the Poynting vector at the time of maximum P-(S-) wave energy in each grid point. Then, the P-wave incident angle is computed by the two propagation directions. Thus, the P- and S-wave ADGICs can obtained Numerical tests show that the proposed method can accurately compute the propagation direction and incident angle of the source and receiver wavefields, thereby achieving high-precision extraction of P- and S-wave ADGICs.
. Extraction of P- and S-wave angle-domain common-image gathers based on fi rst-order velocity-dilatation-rotation equations*[J]. APPLIED GEOPHYSICS, 2020, 17(1): 92-102.
2020, Vol. 17 
