Full Waveform Modelling for Converted Waves Seismic Reflections in Mountainous and Marine Environment
The application of seismic waves allows us to achieve adequate results by compressional wave (P-wave) surveys alone. However, in the presence of gas P-wave transmission disrupts and obscures underlying targets. Many reservoirs don’t present sufficient impedance contrast to the overburden and not reflect P-wave strongly to produce an impedance image. High impedance rock such as basalt or hard volcanic rocks are difficult to image with P-wave. To overcome these challenges shear-wave (S-wave) or converted wave (P-S) surveys are usedfor last 20 years by making the use of down going P waves converting to upcoming S waves at the mode conversion boundaries.The processing of converted waves requires studying asymmetric reflection at the conversion point, difference in geometries and conditions of source and receiver, and the partitioning of energy into orthogonally polarized components. Interpretation of P-S sections incorporates the identification of P-S waves, full waveform modelling, correlation with P-wave sections and depth migration.
The objectives of this study is to model P-S wave reflections in onshore and offshore environment and to examine the major differences in processing of P and P-S wave surveys together with the identifying converted mode reflections by P-wave sources in anisotropic media. To achieve these, realistic mountainous and marine environment models have been developed and synthetic seismograms are generated by full waveform modelling technique. First a mountain foothill model was studied. A Kirchhoff-based technique that includes anisotropic velocities is used for depth migration of P-S waves. The results from depth imaging show that P-S section help in distinguishing amplitude associated with hydrocarbons from those caused by localized stratigraphic changes. Marine model shows a good correlation with identified converted waves. In addition, the full waveform elastic modellingproves useful in finding an appropriate balance between capturing high-quality P-wave data as well as P-S data challenges in a survey.
Key Words: Converted-waves (P-S); P-S Wave; Kirchhoff migration; Depth migration; Gas clouds; Shale diapers
 Caldwell, J. (1999). Marine multicomponent seismology. The Leading Edge, 18, 1274-1282.
 Christeson, G. L., McIntosh, K. D., & Shipley, T. H. (2000). Seismic attenuation in the Costa Rica margin wedge: amplitude modelling of ocean bottom hydrophone data. Earth Planet Sci. Lett., 179, 391-40
 Kim, S.D., Nagihara, S., & Nakamura, Y. (2000). P- and S-wave velocity structures of the Sigbee abyssal plain of the Gulf of Mexico from ocean bottom seismometer data. Gulf Coast AssocGeolSoc (GCAGS) Trans., 50, 475-484.
 Kopp, H. (2002). BSR occurrence along the Sunda margin: evidence from seismic data. Earth Planet Sci. Lett., 197, 225-235.
 Walther, C. H. E. (2003). The crustal structure of the Cocos ridge off Costa Rica. J Geophys Res, 108(B3), 2136.
 Digranes, P., Mjelde, R., Kodaria, S., Shimamura, H., Kanasawa, T., Shiobara, H., & Berg, E. W. (1996). Modelling shear waves in OBS data from the Voring Basin (northern Norway) by 2D ray tracing. PAGEOPH, 147(4), 611-629.
 Mikhailov, O., Johnson, J., Shoshitaishvili, E., & Frasier, C. (2001). Practical approach to joint imaging of multicomponent data. Leading Edge, 20(9), 1016-1021
 Aki, K., & Richards, P. G. (1980). Quantitative seismology: Theory and methods. USA: W. H. Freeman and Sons.
 Frasier, C., & Winterstein, D. (1990). Analysis of conventional and converted mode reflections at Putah Sink, California using three-component data. Geophysics, 55, 646-659.
 Peng, L. Y., Ma, Z. T., Sun, P. Y., & Yang, H. S. (2012). Converted-wave static correction method for thick weathering area. Chinese Journal of Geophysics, 55(1), 76-83.
 Gaiser, J. E., Fowler, P. J., & Jackson, A. R. (1997). Challenges for 3-D converted-wave processing. 67th Ann. Internat. Mtg., Soc. Expl. Geophys., Expanded Abstracts, 1199-1202.
 Garotta, R. (1985). Observation of shear waves and correlation with P events. In G. P. Dohr (Ed.), Seismic shear waves (1-86). USA: Geophysical Press.
 Li, X., Kuhnel, T., & MacBeth, C. (1996). Converted-wave AVO and its implications. 58th Ann. Intl. Mtg., Europ. Assn. Geosci. Eng., M046.
 Stewart, R. R., Gaiser, J. E., Brown, R. J., & Lawton, D. C. (2000). Converted-wave seismic exploration: applications. CREWES Research Report, 12.
 Purnell, G.W. (1992). Imaging beneath a high-velocity layer using converted waves. Geophysics, 57, 1444-1452.
 Rajput, S., Thakur, N. K., & Joshi, A. (2008). Full waveform seismic modelling for gas hydrates studies. 70th EAGE Conference & Exhibition, Rome, Italy.
 Brown, R. J., Stewart, R. R., & Lawton, D. C. (2002). A proposed polarity standard for multicomponent seismic data. Geophysics, 67, 1028-1037.
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