天然气水合物储层弹性波最小二乘逆时偏移研究
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摘要
天然气水合物的弹性性质相比于周围岩层有明显的差异。传统声波成像方法采用声波近似,无法对其弹性性质进行准确地描述,弹性波偏移方法的成像结果分辨率低、中深部成像能量弱、振幅不均衡,存在低频噪声和采集脚印。为此,文中发展了一种弹性波最小二乘逆时偏移方法,在该方法中,推导了准确的弹性波最小二乘理论框架下的偏移算子和反偏移算子。为了提高计算效率并节省内存,引入了基于编码技术的混叠数据弹性波最小二乘方法,将多炮数据叠加为一个超道集,并采用编码技术压制串扰噪声。通过对两个含天然气水合物模型的试算验证了本文方法对天然气水合物储层成像的有效性及优越性。
The elastic properties of gas hydrate are obviously different from those of the surrounding rocks.The traditional acoustic imaging method using acoustic approximation cannot accurately describe the elastic properties.The imaging results of elastic wave migration method have low resolution,weak energy in deep regions,imbalance amplitude,low frequency noise and acquisition footprint.For this reason,the authors have developed an elastic least-squares inverse time migration method.In this method,an accurate migration operator and demigration operator in the framework of the elastic least squares theory are derived.To improve the computation efficiency and save memory,the authors introduced the multisource elastic least-squares migration method based on encoding technique,in which multiple data are added into a supershot and the encoding technique is used to suppress the crosstalk.The effectiveness and superiority of the proposed method for gas hydrate reservoir imaging are verified by the simulation results of two gas hydrate models.
The elastic properties of gas hydrate are obviously different from those of the surrounding rocks.The traditional acoustic imaging method using acoustic approximation cannot accurately describe the elastic properties.The imaging results of elastic wave migration method have low resolution,weak energy in deep regions,imbalance amplitude,low frequency noise and acquisition footprint.For this reason,the authors have developed an elastic least-squares inverse time migration method.In this method,an accurate migration operator and demigration operator in the framework of the elastic least squares theory are derived.To improve the computation efficiency and save memory,the authors introduced the multisource elastic least-squares migration method based on encoding technique,in which multiple data are added into a supershot and the encoding technique is used to suppress the crosstalk.The effectiveness and superiority of the proposed method for gas hydrate reservoir imaging are verified by the simulation results of two gas hydrate models.
引文
[1]Zanoth S R,Saenger E H,Krüger O S,et al.Leaky mode:A mechanism of horizontal seismic attenuation in a gas-hydrate-bearing sediment[J].Geophysics,2007,72(5):E159-E163.
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[3]Sloan E D.Clathrate hydrates of natural gases[M].Marcel Dekker,1990.
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[11]徐明才,刘建勋,柴铭涛,等.青海木里地区天然气水合物反射地震试验研究[J].地质与勘探,2012,48(6):1180-1187.
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[15]Kuehl H,Sacchi M.Least-squares split-step migration using the Hartley transform[C]//Expanded Abstracts of the 69thAnnual SEG Meeting.Society of Exploration Geophysicists,1999:1548-1551.
[16]Le Bras R,Clayton R.An iterative inversion of back-scattered acoustic waves[J].Geophysics,1988,53(4):501-508.
[17]杨其强,张叔伦.最小二乘傅立叶有限差分偏移[J].地球物理学进展,2008,23(2):433-437.
[18]罗国安,武威,李合群,等.快速叠后偏移反褶积算法及应用[J].石油地球物理勘探,2010,45(6):844-849.
[19]黄建平,李振春,孔雪,等.碳酸盐岩裂缝型储层最小二乘偏移成像方法研究[J].地球物理学报,2013,56(5):1-9.
[20]黄建平,曹晓莉,李振春,等.最小二乘逆时偏移在近地表高精度成像中的应用[J].石油地球物理勘探,2014,(1):107-112.
[21]刘玉金,李振春.扩展成像条件下的最小二乘逆时偏移[J].地球物理学报,2015,10:3771-3782.
[22]郭书娟,马方正,段心标,等.最小二乘逆时偏移成像方法的实现与应用研究[J].石油物探,2015,(3):301-308.
[23]曲英铭,黄建平,李振春,等.分层映射法起伏自由地表弹性波正演模拟与波场分离[J].石油地球物理勘探,2016,(2):261-271.
[24]Qu Y,Huang J,Li Z,et al.A hybrid grid method in an auxiliary coordinate system for irregular fluid-solid interface modeling[J].Geophysical Journal International,2017,208(3):1540-1556.
[25]Qu Y,Li Z,Huang J,et al.Elastic full-waveform inversion for surface topography[J].Geophysics,2017,82(5):R269-R285.
[26]曲英铭,黄建平,李振春,等.分层坐标变换法起伏自由地表弹性波叠前逆时偏移[J].地球物理学报,2015,(8):2896-2911.
[27]Dai W,Fowler P,Schuster G.Multi-source least-squares reverse time migration[J].Geophysical Prospecting,2012,60(4):681-695.
[28]Plessix R E,Mulder W A.Frequency-domain finite-difference amplitude-preserving migration[J].Geophysical Journal International,2004,157(3):975-987.
[29]Plessix R.A review of the adjoint-state method for computing the gradient of a functional with geophysical applications[J].Geophysical Journal International,2006,167(2):495-503.
[30]K9hn D,De Nil D,Kurzmann A,et al.On the influence of model parametrization in elastic full waveform tomography[J].Geophysical Journal International,2012,191:325-345.
[31]Qu Y,Li Z,Huang J,et al.Viscoacoustic anisotropic full waveform inversion[J].Journal of Applied Geophysics,2017,136:484-497.
[32]Qu Y,Li Z,Huang J,et al.Multi-scale full waveform inversion for areas with irregular surface topography in an auxiliary coordinate system[J].Exploration Geophysics,2016.
[33]Qu Y,Li Z,Huang J,et al.Irregular surface FWI in an auxiliary coordinate system based on the first-order velocity-stress equation[C]//Expanded Abstracts of the 86thAnnual SEG Meeting.Society of Exploration Geophysicists,2016:1079-1083.
[34]Liu Y,Symes W W,SLi Z.Multisource least-squares extended reverse-time migration with preconditioning guided gradient method[J].SEG Technical Program,Expanded Abstracts,2013:3709-3715.
[2]Stoll R D,Bryan G M.Physical properties of sediments containing gas hydrates[J].J.Geophys.Res.,1979,84:1629-1634.
[3]Sloan E D.Clathrate hydrates of natural gases[M].Marcel Dekker,1990.
[4]Kvenvolden K A.Aprimer on gas hydrates.U.S.Geological Survey[J].Professional Paper 1570,1993:555-561.
[5]Holbrook W S,Hoskins H,Wood W T,et al.Methane hydrate and free gas on the Blake Ridge from vertical seismic profling[J].Science,1996,273:1840-1843.
[6]Guerin G,Goldberg D.Sonic waveform attenuation in gas hydratebearing sediments from the Mallik 2L-38 research well,Mackenzie Delta,Canada[J].Journal of Geophysical Research,2002,107:1029-1085.
[7]Stoll R D,Bryan G M.Physical properties of sediments containing gas hydrates[J].J.Geophys.Res.,1979,84:1629-1634.
[8]Bangs N L B,Sawyer D S,Golvovchenko X.Free gas at the base of the gas hydrate zone in the vicinity of the Chile triple junction[J].Geology,1993,21:905-908.
[9]Hyndman R D,Spence G D.A seismic study of methane hydrate marine bottom simulating reflectors[J].J.Geophys.Res.,1992,97:6683-6698.
[10]徐明才,刘建勋,柴铭涛,等.青海省天峻县木里地区天然气水合物地震响应特征[J].地质通报,2011,30(12):1910-1917.
[11]徐明才,刘建勋,柴铭涛,等.青海木里地区天然气水合物反射地震试验研究[J].地质与勘探,2012,48(6):1180-1187.
[12]Akihisa K,Tezuka K,Senoh O,et al.Well log evaluation of gas hydrate saturation in the miti nankai-trough well,offshore south east Japan[J].SPWLA 43rdannual logging symposium,2002.
[13]Claerbout J.Earth soundings analysis:Processing versus Inversion[J].Black-well Scientific,1992.
[14]Nemeth T,Wu C,Schuster G.Least-squares migration of incomplete reflection data[J].Geophysics,1999,64(1):208-221.
[15]Kuehl H,Sacchi M.Least-squares split-step migration using the Hartley transform[C]//Expanded Abstracts of the 69thAnnual SEG Meeting.Society of Exploration Geophysicists,1999:1548-1551.
[16]Le Bras R,Clayton R.An iterative inversion of back-scattered acoustic waves[J].Geophysics,1988,53(4):501-508.
[17]杨其强,张叔伦.最小二乘傅立叶有限差分偏移[J].地球物理学进展,2008,23(2):433-437.
[18]罗国安,武威,李合群,等.快速叠后偏移反褶积算法及应用[J].石油地球物理勘探,2010,45(6):844-849.
[19]黄建平,李振春,孔雪,等.碳酸盐岩裂缝型储层最小二乘偏移成像方法研究[J].地球物理学报,2013,56(5):1-9.
[20]黄建平,曹晓莉,李振春,等.最小二乘逆时偏移在近地表高精度成像中的应用[J].石油地球物理勘探,2014,(1):107-112.
[21]刘玉金,李振春.扩展成像条件下的最小二乘逆时偏移[J].地球物理学报,2015,10:3771-3782.
[22]郭书娟,马方正,段心标,等.最小二乘逆时偏移成像方法的实现与应用研究[J].石油物探,2015,(3):301-308.
[23]曲英铭,黄建平,李振春,等.分层映射法起伏自由地表弹性波正演模拟与波场分离[J].石油地球物理勘探,2016,(2):261-271.
[24]Qu Y,Huang J,Li Z,et al.A hybrid grid method in an auxiliary coordinate system for irregular fluid-solid interface modeling[J].Geophysical Journal International,2017,208(3):1540-1556.
[25]Qu Y,Li Z,Huang J,et al.Elastic full-waveform inversion for surface topography[J].Geophysics,2017,82(5):R269-R285.
[26]曲英铭,黄建平,李振春,等.分层坐标变换法起伏自由地表弹性波叠前逆时偏移[J].地球物理学报,2015,(8):2896-2911.
[27]Dai W,Fowler P,Schuster G.Multi-source least-squares reverse time migration[J].Geophysical Prospecting,2012,60(4):681-695.
[28]Plessix R E,Mulder W A.Frequency-domain finite-difference amplitude-preserving migration[J].Geophysical Journal International,2004,157(3):975-987.
[29]Plessix R.A review of the adjoint-state method for computing the gradient of a functional with geophysical applications[J].Geophysical Journal International,2006,167(2):495-503.
[30]K9hn D,De Nil D,Kurzmann A,et al.On the influence of model parametrization in elastic full waveform tomography[J].Geophysical Journal International,2012,191:325-345.
[31]Qu Y,Li Z,Huang J,et al.Viscoacoustic anisotropic full waveform inversion[J].Journal of Applied Geophysics,2017,136:484-497.
[32]Qu Y,Li Z,Huang J,et al.Multi-scale full waveform inversion for areas with irregular surface topography in an auxiliary coordinate system[J].Exploration Geophysics,2016.
[33]Qu Y,Li Z,Huang J,et al.Irregular surface FWI in an auxiliary coordinate system based on the first-order velocity-stress equation[C]//Expanded Abstracts of the 86thAnnual SEG Meeting.Society of Exploration Geophysicists,2016:1079-1083.
[34]Liu Y,Symes W W,SLi Z.Multisource least-squares extended reverse-time migration with preconditioning guided gradient method[J].SEG Technical Program,Expanded Abstracts,2013:3709-3715.