基于边界存储的地震波场重构及逆时偏移成像应用研究
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摘要
逆时偏移是基于双程波动理论,没有倾角和横向变速限制,能够解决复杂地质构造成像问题.在逆时偏移成像实现过程中,需要对源波场进行正推和对接收波场进行逆推,由于这两个波场外推方向不一致,需要对其中一个波场(源波场或接收波场)进行存储,这部分存储量很大,是制约逆时偏移成像应用的瓶颈.本文探讨了一种有效的边界存储方法,即先让源波场正推到最大记录时间,在研究区域边界存储所有时刻波场记录,同时记录最大时刻该区域全波场.然后将边界存储波场和最大时刻全波场分别作为边界条件和初始条件,进行波场逆推来重构源波场,这样就解决了源波场与接收波场外推方向不一致的问题,从而可以克服逆时偏移成像存储瓶颈,并将该方法应用到逆时偏移成像.通过简单层状模型和复杂逆掩断层模型试验,并和直接存储方法进行了对比,证明了该方法的有效性.
Reverse time migration is based on the two-way wave theory,there is no limitation of the steep dip and strong lateral velocity variation. It can be used to solve the imaging problem of complex geological structures. During the implementation process of reverse time migration,it is necessary that the source wavefield is forward and the receiver wavefield is backforward. Due to the inconsistency of the two wavefield extrapolation direction, one wavefield( source or receiver wavefield) need to be stored. The storage is too large and becomes the bottle neck of reverse time migration. In this paper,an effective method of boundary storage is discussed,namely,the source wavefield is forward to the maximum recording time, and wavefields all the time are stored at the boundary of the study area. At the same time,the full wavefield at the maximum time is recorded. Then we can reconstruct the source wavefield through the wavefield backward under the condition of using the all storage boundary wavefield and the full wavefield at the maximum time as boundary and initial conditions,respectively. It can solve the extrapolation direction inconsistent problem of the source and receiver wavefield and overcome the storage bottleneck of reverse time migration. Afterwards,the method is applied to the reverse time migration imaging. By using a simple layered model and a complex overthrust fault model,the validity of the method is proved through RTM test and comparing with the direct storage method.
Reverse time migration is based on the two-way wave theory,there is no limitation of the steep dip and strong lateral velocity variation. It can be used to solve the imaging problem of complex geological structures. During the implementation process of reverse time migration,it is necessary that the source wavefield is forward and the receiver wavefield is backforward. Due to the inconsistency of the two wavefield extrapolation direction, one wavefield( source or receiver wavefield) need to be stored. The storage is too large and becomes the bottle neck of reverse time migration. In this paper,an effective method of boundary storage is discussed,namely,the source wavefield is forward to the maximum recording time, and wavefields all the time are stored at the boundary of the study area. At the same time,the full wavefield at the maximum time is recorded. Then we can reconstruct the source wavefield through the wavefield backward under the condition of using the all storage boundary wavefield and the full wavefield at the maximum time as boundary and initial conditions,respectively. It can solve the extrapolation direction inconsistent problem of the source and receiver wavefield and overcome the storage bottleneck of reverse time migration. Afterwards,the method is applied to the reverse time migration imaging. By using a simple layered model and a complex overthrust fault model,the validity of the method is proved through RTM test and comparing with the direct storage method.
引文
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Feng B,Wang H Z.2012.Reverse time migration with source wavefield reconstruction strategy[J].Journal of Geophysics and Engineering,9(1):69-74.
Guan H,Kim Y C,Ji J,et al.2009.Multistep reverse time migration[J].The Leading Edge,28(4):442-447.
Hu H,Liu Y K,Chang X,et al.2013.Analysis and application of boundary treatment for the computation of reverse-time migration[J].Chinese J.Geophys.(in Chinese),56(6):2033-2042,doi:10.6038/cjg20130624.
Liu W,Wang Y.2008.Target-oriented reverse time migration for twoway prestack depth imaging[C].//Society of Exploration Geophysicists,SEG Technical Program Expanded Abstracts,2326-2330.
Nguyen B D,Mc Mechan G A.2015.Five ways to avoid storing source wavefield snapshots in 2D elastic prestack reverse time migration[J].Geophysics,80(1):S1-S18.
Shi Y,Ke X,Zhang Y Y.2015.Analyzing the boundary conditions and storage strategy for reverse time migration[J].Progress in Geophysics(in Chinese),30(2):581-585,doi:10.6038/pg20150214.
Sun W J,Fu L Y.2013.Two effective approaches to reduce data storag in reverse time migration[J].Computers&Geosciences,56:69-75.
Symes W W.2007.Reverse time migration with optimal checkpointin[J].Geophysics,72(5):SM213-SM221.
Wang B L,Gao J H,Chen W C,et al.2012.Efficient boundary storag strategies for seismic reverse time migration[J].Chinese J.Geophys.(in Chinese),55(7):2412-2421,doi:10.6038/j.issn.0001-5733.2012.07.025.
Yang R H,Chang X,Liu Y K.2010.The influence factors analyses o imaging precision in pre-stack reverse time migration[J].Chines J.Geophys.(in Chinese),53(8):1902-1913,doi:10.3969/j.issn.0001-5733.2010.08.016.
Yang R H,Mao W J,Chang X.2015.An efficient seismic modeling in viscoelastic isotropic media[J].Geophysics,80(1):T63-T81.
胡昊,刘伊克,常旭,等.2013.逆时偏移计算中的边界处理分析及应用[J].地球物理学报,56(6):2033-2042,doi:10.6038/cjg20130624.
石颖,柯璇,张莹莹.2015.逆时偏移边界条件与存储策略分析[J].地球物理学进展,30(2):581-585,doi:10.6038/pg20150214.
王保利,高静怀,陈文超,等.2012.地震叠前逆时偏移的有效边界存储策略[J].地球物理学报,55(7):2412-2421,doi:10.6038/j.issn.0001-5733.2012.07.025.
杨仁虎,常旭,刘伊克.2010.叠前逆时偏移影响因素分析[J].地球物理学报,53(8):1902-1913,doi:10.3969/j.issn.0001-5733.2010.08.016.
Claerbout J F.1971.Toward a unified theory of reflector mapping[J].Geophysics,36(3):467-481.
Clapp R G.2009.Reverse time migration with random boundaries[C].//Society of Exploration Geophysicists,SEG Technical Program Expanded Abstracts,2809-2813.
Feng B,Wang H Z.2012.Reverse time migration with source wavefield reconstruction strategy[J].Journal of Geophysics and Engineering,9(1):69-74.
Guan H,Kim Y C,Ji J,et al.2009.Multistep reverse time migration[J].The Leading Edge,28(4):442-447.
Hu H,Liu Y K,Chang X,et al.2013.Analysis and application of boundary treatment for the computation of reverse-time migration[J].Chinese J.Geophys.(in Chinese),56(6):2033-2042,doi:10.6038/cjg20130624.
Liu W,Wang Y.2008.Target-oriented reverse time migration for twoway prestack depth imaging[C].//Society of Exploration Geophysicists,SEG Technical Program Expanded Abstracts,2326-2330.
Nguyen B D,Mc Mechan G A.2015.Five ways to avoid storing source wavefield snapshots in 2D elastic prestack reverse time migration[J].Geophysics,80(1):S1-S18.
Shi Y,Ke X,Zhang Y Y.2015.Analyzing the boundary conditions and storage strategy for reverse time migration[J].Progress in Geophysics(in Chinese),30(2):581-585,doi:10.6038/pg20150214.
Sun W J,Fu L Y.2013.Two effective approaches to reduce data storag in reverse time migration[J].Computers&Geosciences,56:69-75.
Symes W W.2007.Reverse time migration with optimal checkpointin[J].Geophysics,72(5):SM213-SM221.
Wang B L,Gao J H,Chen W C,et al.2012.Efficient boundary storag strategies for seismic reverse time migration[J].Chinese J.Geophys.(in Chinese),55(7):2412-2421,doi:10.6038/j.issn.0001-5733.2012.07.025.
Yang R H,Chang X,Liu Y K.2010.The influence factors analyses o imaging precision in pre-stack reverse time migration[J].Chines J.Geophys.(in Chinese),53(8):1902-1913,doi:10.3969/j.issn.0001-5733.2010.08.016.
Yang R H,Mao W J,Chang X.2015.An efficient seismic modeling in viscoelastic isotropic media[J].Geophysics,80(1):T63-T81.
胡昊,刘伊克,常旭,等.2013.逆时偏移计算中的边界处理分析及应用[J].地球物理学报,56(6):2033-2042,doi:10.6038/cjg20130624.
石颖,柯璇,张莹莹.2015.逆时偏移边界条件与存储策略分析[J].地球物理学进展,30(2):581-585,doi:10.6038/pg20150214.
王保利,高静怀,陈文超,等.2012.地震叠前逆时偏移的有效边界存储策略[J].地球物理学报,55(7):2412-2421,doi:10.6038/j.issn.0001-5733.2012.07.025.
杨仁虎,常旭,刘伊克.2010.叠前逆时偏移影响因素分析[J].地球物理学报,53(8):1902-1913,doi:10.3969/j.issn.0001-5733.2010.08.016.