Extraction of amplitude-preserving angle gathers based on vector wavefield reverse-time migration
Yang Jia-Jia1,2, Luan Xi-Wu1,2, He Bing-Shou2,3, Fang Gang1,2, Pan Jun1,2, Ran Wei-Min1,3, and Jiang Tao1
1. The Key Laboratory of Marine Hydrocarbon Resource and Environment Geology, Ministry of Land and Resources, Qingdao Institute of Marine Geology, Qingdao 266071, China.
2. Function Laboratory for Marine Mineral Resource Geology and Exploration, National Laboratory for Marine Science and Technology, Qingdao 266071, China.
3. Key Lab of Submarine Geosciences and Prospecting Techniques, Ministry of Education, Ocean University of China, Qingdao 266071, China.
Abstract Angle-domain common-image gathers (ADCIGs) transformed from the shot-domain common-offset gathers are input to migration velocity analysis (MVA) and prestack inversion. ADCIGs are non-illusion prestack inversion gathers, and thus, accurate. We studied the extraction of elastic-wave ADCIGs based on amplitude-preserving elastic-wave reverse-time migration for calculating the incidence angle of P- and S-waves at each image point and for different source locations. The P- and S-waves share the same incident angle, namely the incident angle of the source P-waves. The angle of incidence of the source P-wavefield was the difference between the source P-wave propagation angle and the reflector dips. The propagation angle of the source P-waves was obtained from the polarization vector of the decomposed P-waves. The reflectors’ normal direction angle was obtained using the complex wavenumber of the stacked reverse-time migration (RTM) images. The ADCIGs of P- and S-waves were obtained by rearranging the common-shot migration gathers based on the incident angle. We used a horizontally layered model, the graben medium model, and part of the Marmousi-II elastic model and field data to test the proposed algorithm. The results suggested that the proposed method can efficiently extract the P- and S-wave ADCIGs of the elastic-wave reverse-time migration, the P- and S-wave incident angle, and the angle-gather amplitude fidelity, and improve the MVA and prestack inversion.
This work is supported by Financially Supported by Qingdao National Laboratory for Marine Science and Technology (No.QNLM2016ORP0206), National Science and Technology Major Project (No. 2016ZX05027-002), China Postdoctoral Science Foundation (No. 2017M612219), National Key R&D Plan (Nos. 2017YFC0306706 and 2017YFC0307400), Financially Supported by Qingdao National Laboratory for Marine Science and Technology (No.QNLM201708), Natural Science Foundation of Shandong Province (No. ZR2016DB10), National Natural Science Foundation of China (Nos. 41674118, 41504109, and 41506084), Key Laboratory of Submarine Geosciences Foundation of SOA (No. KLSG1603), and Qingdao Municipal Applied Research Projects (No. 2016238).
Cite this article:
. Extraction of amplitude-preserving angle gathers based on vector wavefield reverse-time migration[J]. APPLIED GEOPHYSICS, 2017, 14(4): 492-504.
[1]
Aki, K., and Richards, P. G., 1980, Quantitative seismology, theory and methods: W. H. Freeman and Co, 63-68.
[2]
Biondi, B., and Symes, W. W., 2004, Angle-domain common-image gathers for migration velocity analysis by wavefield-continuation imaging: Geophysics, 69(5), 1283-1298.
[3]
Cerveny´, V., 2001, Seismic ray theory: Cambridge University Press, USA, 17-18.
[4]
Dickens, A., and Winbow, G. A., 2011, RTM angle gathers using Poynting vectors: 81st Ann. Internat. Mtg., Soc. Expi.Geophys., Expanded Abstracts, 3109-3113.
Loewenthal, D., and Mulfti, I. R., 1983, Reverse time migration in spatial frequency domain: Geophysics, 46(3), 627-635.
[7]
McMechan, G. A., 1983, Migration by extrapolation of time-dependent boundary values: Geophysical Prospecting, 31(2), 413-420.
[8]
Pinsky, M., 2009, Introduction to Fourier analysis and wavelets: American Mathematics Society.
[9]
Sava, P., and Fomel, S., 2006a, Time-shift imaging condition in seismic migration: Geophysics, 71(6), S209-S217.
[10]
Sava, P., and Fomel, S., 2006b, Time-shift imaging condition for converted waves: 76th Ann. Internat. Mtg., Soc. Expi.Geophys., Expanded Abstracts, 2460-2464.
[11]
Sava, P., and Fomel, S., 2005a, Wave-equation common-angle gathers for converted waves: 75th Ann. Internat. Mtg., Soc. Expi.Geophys., Expanded Abstracts, 947-950.
[12]
Sava, P., and Fomel, S., 2005b, Coordinate-independent angle-gathers for wave equation migration: 75th Ann. Internat. Mtg., Soc. Expi. Geophys., Expanded Abstracts, 2052-2055.
[13]
Sava, P., and Fomel, S., 2003, Angle-domain common-image gathers by wavefield continuation methods: Geophysics, 68(3), 1065-1074.
[14]
Sun, R., McMechan, G. A., Hsian, H., and Chow, J., 2004, Separating P and S-waves in prestack 3D elastic seismograms using divergence and curl: Geophysics, 69(1), 286-297.
[15]
Sun, R., Chow, J., and Chen, K. J., 2001, Phase correction in separating P- and S-waves in elastic data: Geophysics, 66(5), 1515-1518.
[16]
Sun, R., 1999, Separating P- and S-waves in a prestack 2-dimensional elastic seismogram: 61st Conference, European Association of Geoscientists and Engineers, Extended Abstracts, 6-23.
[17]
Sun, R., McMechan, G. A., and Chuang, H., 2011, Amplitude balancing in separating P and S-waves in 2D and 3D elastic seismic data: Geophysics, 76(3), S103-S113.
[18]
Tang, C., McMechan, G. A., and Wang, D., 2017, Two algorithms to stabilize multidirectional Poynting vectors for calculating angle gathers from reverse time migration: Geophysics, 82(2), S129-S141.
[19]
Vyas, M., Nichols, D., and Mobley, E., 2011, Efficient RTM angle gathers using source directions: 81st Ann. Internat. Mtg., Soc. Expi. Geophys., Expanded Abstracts, 3104-3108.
[20]
Wang, B. L., Gao, J. H., Chen, W. C., et al., 2013, Extracting efficiently angle gathers using Poynting vector during reverse time migration: Chinese Journal of Geophysics (in Chinese), 56(1), 262-268.
[21]
Whitmore, N. D., 1983, Iterative depth migration by backward time propagation: 53th Ann. Internat. Mtg., Soc. Expi. Geophys., Expanded Abstracts, 382-385.
[22]
Xie, X., and Yang, H., 2008, A full-wave equation based seismic illumination analysis method: 70th Ann. Internat. Conference and Exhibition, EAGE, Extended Abstracts, 284-288.
[23]
Xie, X., and Wu, R. S., 2002, Extracting angle domain information from migrated wavefields: 72nd Ann. Internat. Mtg., Soc. Expi. Geophys., Expanded Abstracts, 1360-1363.
[24]
Xu, S., Zhang, Y., and Tang, B., 2011, 3D angle gathers from reverse time migration: Geophysics, 76(2), S77-S92.
[25]
Xu, S., Zhang, Y., and Lambaré, G., 2010, Antileakage Fourier transform for seismic data regularization in higher dimension: Geophysics, 75(6), WB113-WB120.
[26]
Xu, S., Chauris, H., Lambaré, G., et al., 2001, Common-angle migration: A strategy for imaging complex media: Geophysics, 66(6), 1877-1894.
[27]
Xu, S., Chauris, H., Lambare, G., et al., 1998, Common angle image gather - A strategy for imaging complex media: 68th Ann. Internat. Mtg., Soc. Expi. Geophys., Expanded Abstracts, 1538-1541.
[28]
Yan, R., and Xie, X., 2012, An angle-domain imaging condition for elastic reverse time migration and its application to angle gather extraction: Geophysics, 77(5), S105-S115.
[29]
Yan, R., and Xie, X., 2011, Angle gather extraction for acoustic and isotropic elastic RTM: 81st Ann. Internat. Mtg., Soc. Expi. Geophys., Expanded Abstracts, 3141-3146.
[30]
Yang, J. J., Luan, X. W., Fang, G., et al., 2016, Elastic reverse-time migration based on amplitude-preserving P- and S-wave separation: Applied Geophysics, 13(3), 500-510.
[31]
Yoon, K., Guo, M., Cai, J., et al., 2011, 3D RTM angle gathers from source wave propagation direction and dip of reflector: 81st Ann. Internat. Mtg., Soc. Expi. Geophys., Expanded Abstracts, 1057-1060.
[32]
Yoon, K., and Marfurt, K. J., 2006, Reverse-time migration using the Poynting vector: Exploration Geophysics, 37(1), 102-107.
[33]
Zhang, Q., and McMechan, G. A., 2011a, Common-image gathers in the incident phase-angle domain from reverse time migration in 2D elastic VTI media: Geophysics, 76(6), S197-S206.
[34]
Zhang, Q., and McMechan, G. A., 2011b, Direct vector-field method to obtain angle-domain common-image gathers from isotropic acoustic and elastic reverse-time migration: Geophysics, 76(5), WB135-WB149.
2017, Vol. 14 
