Seismic imaging of complex structures by integrating pre-stack time migration and surface stacking methods

Authors

Post graduate of M.Sc. in Petroleum Exploration/Shahrood, Shahrood.

Abstract

The conventional approach to seismic data analysis consists of two main steps: estimating seismic velocities, (the subsurface macro-model), and seismic imaging, (mapping of the reflected seismic energy to the reflector positions). The aim and the major challenge in the seismic data analysis is the construction of the best undistorted image. This challenge would be more problematic when geometrical complexity and lateral heterogeneity increase. It is obvious that conventional reflection seismic data processing methods cannot solve the problem of seismic imaging in complex geological structures. It is because of that most of those processing methods are strongly depended on seismic velocity propagation model. However, obtaining a precise velocity model as accurate as possible is always a controversial task. For this purpose, imaging methods are employed that do not rely on the explicit knowledge of subsurface velocity model. Therefore, in most of the researches of new seismic imaging methods, efforts are oriented to develop velocity independent imaging algorithms. The first idea of velocity-independent time-domain seismic imaging belongs to authors considered decomposing seismic data into a range of local slopes. Then methods that consider inversion of full waveform from the data were introduced. However, these methods are not the ultimate solution, because we need the velocity model for final depth imaging. Thus some methods are introducing to use advantage of pre-stack migration with iterative velocity model updating while using seismic imaging methods that don’t fully rely on velocity model. These integration methods aims to combine new updating formula for the first part (estimating seismic velocities) of the processing chain and use new velocity independent methods for the second part (Seismic imaging).
Time migration is a common fast and robust process of obtaining seismic image. This process is considered adequate for the areas with mild lateral velocity variation. Moreover, time migration produces images in very specific time migration coordinates (x0; t0). However, even mild lateral velocity variations can significantly distort subsurface structures on the time migrated images. The main reason that this velocity variation will make distortion in the section is that reflected and diffracted energies will be placed in wrong positions. If this displacing could be slightly removed by any operator, e. g. Kirchhoff migration operator, in each offset section, another surface operator could be used to stack offset sections and enhance the final migrated section. In this study, we selected pre-stack time imaging with Kirchhoff migration algorithm method and the common reflection surface stack method for integration. Common reflection surface stack method is among velocity independent methods used for imaging in complex structures. The CRS operator will gathers any reflected and/or diffracted energy that could not be gathered by the conventional Kirchhoff summation operator. Thus if the geometrical distortions were corrected by the Kirchhoff operator and reflected energies were placed in their true locations, CRS operator will collects all the related diffracted energy from a depth point and will coherently stack these energies to image that point. The equation that comes in the following is the Kirchhoff operator:

that defines the wave-field parameter, ΔP in each (x, t) point. To integrate these two methods, the CRS operator would be created for each (x, t) point and will be inserted in the above equation. These equations are:
and
.
where the angles are the take-off and emergence angle of the central ray and Ki are wave-front curvatures. aCO and bCO are related to x and t, respectively. Diffraction curve would be obtained for each point and the CRS surface would be created for that point.
To investigate the efficiency of this method, the algorithm applied on a 2D seismic data. This data is from west of Iran which contains complex geometry with mild to strong lateral velocity change. After pre-processing steps, a smooth initial velocity model was derived for performing ray tracing. The kinematic ray tracing was used to define the common reflection surface operator. Afterwards, data were processed by Kirchhoff migration. In the next step, velocity model were corrected for residual move out. Finally pre-stack data was migrated again by the new corrected velocity model. This section should be compared with the result of PSTM and CRS integration method. The new migrated section could better shows faulting and bending of the reflectors. High thickness of Gachsaran formation in the region and strong lateral velocity change in different parts of the section, makes low illumination of the beneath Gachsaran structure. However, the new algorithm could gathers as much as possible reflected and/or diffracted energy from those structures in the data. Therefore, more clear structures and reflectors would be observed in the section and the general quality of the data would be enhanced. Finally, it could be concluded that by applying this proposed integration method will gives high quality image by increasing the signal to noise ratio and solving the problem of conflicting dips.

Keywords

Main Subjects

References

ریاحی، م. و بازرگانی، ف.، 1383، بررسی کارایی روش مهاجرت PSPC در پردازش داده‌‌‌های لرزه‌ای به‌دست آمده از محیط‌های دارای تغییرات جانبی سرعت، م. فیزیک زمین و فضا، 30(2)، 91-79.
سلیمانی، م.، شاهسونی، ه. و مان، ی.، 1392، شناسایی گسل‌ها در داده‌های لرزه‌نگاری بازتابی به‌روش سطح پراش مشترک بررسی موردی، منطقة گرابن راین، آلمان، م. فیزیک زمین و فضا، 39(4)، 44-31.
نبی‌بید هندی، م.، قوامی، ش. و مرادی، م.، 1383، بررسی و مقایسة کوچ‌‌های زمانی قبل و پس از برانبارش، م. فیزیک زمین و فضا، 30(2)، 63-55.
 
Alaei B., 2006, An integrated procedure for migration velocity analysis in complex structures of thrust belts, Journal of Applied Geophysics, 59, 89-105.
Al-Yahya, K. M., 1989, Velocity analysis by iterative profile migration, Geophysics, 54(06), 718-729.
Baykulov, M., 2009, Seismic imaging in complex media with the Common Reflection Surface stack, Ph.D. Thesis, Hamburg University.
Baykulov, M., Brink, H. J., Gajewski, D. and Yoon, M. K., 2009, Revisiting the structural setting of the Glueckstadt Graben salt stock family, North German Basin, Tectonophysics, 470, 162-172. doi: 10.1016/j.tecto.2008.05.027.
Bergler, S., 2001, The common reflection surface stack for common offset- theory and application, Master Thesis Karlsruhe University.
Biondi, B., 2006, 3D seismic imaging, investigations in geophysics, 14, SEG Publishing, Tulsa.
Bóna, A., 2011, Shot-gather time migration of planar reflectors without velocity model, Geophysics, 76(2), S93-S101, doi: 10.1190/1.3549641.
Bongajum, E., Milkereit, B., Adam, E. and Meng, Y., 2012, Seismic imaging in hardrock environments: the role of heterogeneity? Tectonophysics, 572-573, 7-15, doi: 10.1016/j.tecto.2012.03.003.
Burnett, W. A., 2011, Multiazimuth velocity analysis using velocity-independent seismic imaging, Ph.D. thesis, University of Austin at Texas.
Cameron, M., Fomel, S. and Sethian, J., 2008, Time-to-depth conversion and seismic velocity estimation using time-migration velocity, Geophysics, 73(5), 205-210.
Canales, J. P., Tucholke, B. E. and Collins, J. A., 2004, Seismic reflection imaging of an oceanic detachment fault: Atlantis megamullion (Mid-Atlantic Ridge), Earth and Planetary Science Letters, 222, 543-560. doi: 10.1016/j.epsl.2004.02.023.
Docherty, P., 1991, A brief comparison of some Kirchhoff integral formulas for migration and inversion. Geophysics, 56, 1164-1169.
Dong, L., Zhenchun, L., Xiaodong, S., Ning, Q., and Xuefeng, Z., 2010, Prestack seismic data enhancement with the common-offset common reflection surface (CO CRS) Stack, 3rd International Conference on Biomedical Engineering and Informatics, BMEI.
Druzhinin, A., MacBeth, C. and Hitchen, K., 1999, Prestack depth imaging via model-independent stacking, Journal of Applied Geophysics, 42, 157-167.
Fehler, M. C. and Huang, L., 2002, Modern imaging using seismic reflection data, Annual Review of Earth Planetary Sciences, 30, 259-284.
Fomel, S., 2003, Time migration velocity analysis by velocity continuation. Geophysics, 68(5), 1662-1672.
Garabito, Oliva, P., C. and Cruz, J. C. R., 2011, Numerical analysis of the finite-offset common-reflection-surface travel time approximations, Journal of Applied Geophysics, 74, 89-99.
Garabito, C., 2014, Kirchhoff-type pre-stack time migration using the CRS stacking operator, 76th EAGE Conference & Exhibition.
Gelius, L. J. and Tygel, M., 2015, Migration-velocity building in time and depth from 3D (2D) Common-Reflection-Surface (CRS) stacking - theoretical framework, Studia Geophysica et Geodaetica, 59(2), 253-282. doi: 10.1007/s11200-014-1036-6.
Halley, P., Sule, R. and Sanny, T. A., 2009, Application of 2D common offset common reflection surface (CO-CRS) stack method towards synthetic data, 33rd annual convention and exhibition of Indonesian petroleum association.
Hinsch, R., Krawczyk, C. M., Gaedicke, C., Giraudo, R. and Demuro, D., 2002, Basement control on oblique thrust sheet evolution: seismic imaging of the active deformation front of Central Andes Bolivia. Tectonophysics, 355, 23-39, doi: 10.1016/S0040-1951(02)00132-4.
Höcht, G., de Bazelaire, E., Majer, P. and Hubral, P., 1999, Seismics and optics: hyperbolae and curvatures, Journal of Applied Geophysics, 42(3, 4), 261-281.
Hua, B. and McMechan, G. A., 2003, Parsimonious 2D pre-stack Kirchhoff depth migration, Geophysics, 68, 1043-1051.
Hubral, P., 1983, Computing true amplitude reflections in a laterally inhomogeneous earth, Geophysics, 48(8), 1051-1062.
Hubral, P., 1999, Macro model independent seismic reflection imaging, Journal of Applied Geophysics, 42(3-4), 60-73.
Jäger, R., Mann, J., Höcht, G. and Hubral, P., 2001, Common-reflection-surface stack: image and attributes, Geophysics, 66(1), 97-109.
Karazincir, M. H. and Gerrard, C. M., 2006, Explicit high order reverse time pre-stack depth migration, Expanded Abstracts, SEG, 2353-2357.
Keydar, S., Medvedev, B., Al-Zoubi, A., Ezersky, M. and Akkawi, E., 2013, 3D imaging of Dead Sea area using weighted multipath summation: a case study, International Journal of Geophysics, 2013, Article ID 692452, 1-7, doi: 10.1155/2013/692452.
Khoshnavaz, M. and Urosevic, M., 2013, A comparative overview of velocity-independent imaging's methods, ASEG Extended Abstracts, 2013, 1-5. doi: 10.1071/ASEG2013ab078.
Landa, E., Fomel, S. and Moser, T. J., 2006, Path-integral seismic imaging, Geophysical Prospecting, 54, 491-503, doi: 10.1111/j.1365-2478.2006.00552. x.
Leite, L. W. B., Lima, H. M., Heilmann, B. Z. and Mann, J., 2010, CRS-based Seismic Imaging in complex marine geology, 72nd EAGE Conference & Exhibition, Barcelona, Spain, P396.
Liu, Q. and Gu, Y. J., 2012, Seismic imaging: From classical to adjoint tomography, Tectonophysics, 566-567, 31-66, doi: 0.1016/j.tecto.2012.07.006.
Mann, J., Jäger, R., Müller, T., Höcht, G. and Hubral, P., 1999, Common-reflection-surface-stack, a real data example, Journal of Applied Geophysics., 42(3,4), 301-318.
Mann, J., 2002, Extensions and applications of the common-reflection-surface stack method, Logos Verlag, Berlin.
Matsushima, J., Okubo, Y., Rokugawa, S., Yokota, T., Tanaka, K., Tsuchiya, T. and Narita, N., 2003, Seismic reflector imaging by prestack time migration in the Kakkonda geothermal field, Japan, Geothermics, 32, 79-99, doi: 10.1016/S0375-6505(02)00052-4.
Menyoli, E., Gajewski, D. and Huebscher, C., 2004, Imaging of complex basin structure with common reflection surface (CRS) stack method, Geophysical Journal International, 157, 1206-1216, doi: 10.1111/j.1365-246X.2004.02268. x.
Müller, T., 1999, The Common reflection surface stack method – seismic imaging without explicit knowledge of the velocity model, Der Andere Verlag, Bad Iburg.
Nita, B. G., 2006, A comparison of the imaging conditions and principles in depth migration algorithms, International journal of tomography and statistics, 4(6), 5-16.
Ottolini, R., 1983, Velocity independent seismic imaging, in SEP-37, Stanford Exploration Project, 59-68.
Prüssmann, J., Frehers, S., Ballesteros, R., Caballero, A. and Clemente, G., 2008, CRS based depth model building and imaging of 3D seismic data from the Gulf of Mexico Coast, Geophysics, 73, 303-311.
Robein, E., 2003, Velocities, time imaging and depth imaging in reflection seismic, principles and methods, EAGE Press, Netherlands.
Robein, E., 2010, Seismic imaging, EAGE Press, Netherlands.
Santos, H. B., Schleicher, J. and Novais, A., 2013, Initial-model construction for MVA techniques, 75th EAGE Conference and Exhibition incorporating SPE EUROPEC.
Sava, P. and Hill, S., 2009, Overview and classification of wavefield seismic imaging

methods, The Leading edge, 28(2), 170-183, doi: 10.1190/1.3086052.
Sava, P. and Fomel, S., 2006, Time-shift imaging condition in seismic migration, Geophysics, 71(6), S209-S217, doi: 10.1190/1.2338824.
Schleicher, J., Costa, J. C. and Novais, A., 2008, Time-migration velocity analysis by image-wave propagation of common-image gathers, Geophysics, 73(5), 161-171.
Schultz, P. and Sherwood, J., 1980, Depth migration before stack, Geophysics, 45, 376-393.
Siliqi, R., Herrmann, P., Prescott, A. and Capar, L., 2007, Automatic dense high order RMO picking EAGE 69th Conference & Exhibition, Extended abstracts, PO37.
Tomas, C. and Gallo, C., 2014, 3D common offset CRS for data preconditioning, 76th EAGE Conference & Exhibition.
Tygel, M., Ursin, B., Iversen, E. and de Hoop, M. V., 2009, An interpretation of CRS attributes of time-migrated reflections, WIT Reports, 13, 260-268.
Virieux, J. and Operto, S., 2009, An overview of full-waveform inversion in exploration geophysics, Geophysics, 74(6), 1-26.
Wang, T. K., Chen, M. K., Lee, C. S. and Xia, K., 2006, Seismic imaging of the transitional crust across the northeastern margin of the South China Sea, Tectonophysics, 412, 237–254, doi: 10.1016/j.tecto.2005.10.039.
Yang, K., Bao-shu Chen, B. S., Wang, X., J., Yang, X., J. and Liu, J. R., 2012, Handling dip discrimination phenomenon in common-reflection-surface stack via combination of output-imaging-scheme and migration/demigration, Geophysical Prospecting, 60, 255-269.
Yoon, M. K., Baykulov, M., Dümmong, S., Brink, H. J. and Gajewski, D., 2009, Reprocessing of deep seismic reflection data from the North German Basin with the common reflection surface stack, Tectonophysics, 472, 273-283, doi: 10.1016/ j. tecto. 2008. 05. 010.
Yilmaz, O., 2001, Seismic data analysis, Society of Exploration Geophysicists.
Zhao, D., Huang, Z., Umino, N., Hasegawa, A. and Yoshida, T., 2011, Seismic imaging of the Amur–Okhotsk plate boundary zone in the Japan Sea, Physics of the Earth and Planetary Interiors, 188, 82-95, doi: 10.1016/j.pepi.2011.06.013.
Journal of the Earth and Space Physics
Volume 42, Issue 2 - Serial Number 2
September 2016
Pages 293-308

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