正演子波响应特征及逆时成像分析
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摘要
采用一阶形式和二阶形式的地震波动方程,开展了二维地震子波正演响应理论研究,并以二维均匀介质速度模型为例,将不同相位的Ricker子波作为输入子波,进行了数值模拟。结果表明,一阶形式的子波响应与输入子波波形差异较大,且存在较大的相位移,同时,其比值谱与频率呈线性正比关系;而二阶形式的子波响应与输入子波波形差异较小,相位移较小,其比值谱几乎不随频率变化。因此二阶形式的波动方程具有更好的保形特征,可以实现任意期望子波波形的正演数值模拟。在上述研究的基础上,讨论了逆时子波波场响应特征,并以一维层状介质反射系数模型为例,进行了一阶形式和二阶形式波动方程的相关型和反射率型逆时偏移成像试验,结果表明,当震源波场与接收波场的子波波形相一致时,低频逆时噪声能量最弱,成像效果最佳;反之,成像剖面中的反射界面与真实的地层界面位置会存在时差,同时,低频逆时噪声能量较强。因此,保持子波波形的一致性是实现高精度相关型、反射率型逆时偏移成像的前提。
Taking 2D homogeneous medium velocity model as example, by using the first-order and second-order wave equation with input wavelet of different phase Ricker wavelet,we carried out numerical simulation.The computation results show that there is a large difference between the wave field response of the first-order wave equation and the input wavelet waveform,as well as the phase shift.Meanwhile,the ratio amplitude spectrum has linear proportional relationship with frequency.However,the wave field response characteristics of the second-order wave equation and the input wavelet waveform are almost the same with small phase shift, and the ratio amplitude spectrum is almost not changed with the frequency.Therefore,the second-order wave equation has the property of shape preservation,and can achieve forward modeling with expected wavelet form.Based on the above analysis,the response characteristic of inverse time wavefield was discussed,then,the correlation type and reflectivity type reverse-time migration on the 1D layered model was carried out.The results show that if the wavelet waveform of the source wave field and receive wave field are consistent, the image results are the best with lowest low frequency reverse -time noise;otherwise,there is a time shift between the reflection interface on the imaging section and actual formation interface,and the energy of the low frequency reverse-time noise is stronger.Therefore, maintaining the consistence of wavelet waveform is the prerequisite of the high-precision correlation and reflectivity reverse-time migration
Taking 2D homogeneous medium velocity model as example, by using the first-order and second-order wave equation with input wavelet of different phase Ricker wavelet,we carried out numerical simulation.The computation results show that there is a large difference between the wave field response of the first-order wave equation and the input wavelet waveform,as well as the phase shift.Meanwhile,the ratio amplitude spectrum has linear proportional relationship with frequency.However,the wave field response characteristics of the second-order wave equation and the input wavelet waveform are almost the same with small phase shift, and the ratio amplitude spectrum is almost not changed with the frequency.Therefore,the second-order wave equation has the property of shape preservation,and can achieve forward modeling with expected wavelet form.Based on the above analysis,the response characteristic of inverse time wavefield was discussed,then,the correlation type and reflectivity type reverse-time migration on the 1D layered model was carried out.The results show that if the wavelet waveform of the source wave field and receive wave field are consistent, the image results are the best with lowest low frequency reverse -time noise;otherwise,there is a time shift between the reflection interface on the imaging section and actual formation interface,and the energy of the low frequency reverse-time noise is stronger.Therefore, maintaining the consistence of wavelet waveform is the prerequisite of the high-precision correlation and reflectivity reverse-time migration
引文
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[14]陈可洋.声波和弹性波叠后逆时深度偏移[J].天然气勘探与开发,2010,33(3):20-21,49
[15]陈可洋.高阶交错网格有限差分法弹性波叠前逆时深度偏移[J].油气地球物理,2010,8(3):1-4
[16]刘红伟,李博,刘洪,等.地震叠前逆时偏移高阶有限差分算法及GPU实现[J].地球物理学报,2010,53 (7):1725-1733
[17]刘红伟,刘洪,邹振,等.地震叠前逆时偏移中的去噪与存储[J].地球物理学报,2010,53(9):2171-2180
[18]孙文博,孙赞东.基于伪谱法的VSP逆时偏移及其应用研究[J].地球物理学报,2010,53(9):2196- 2203
[19]杨仁虎,常旭,刘伊克.叠前逆时偏移影响因素分析[J].地球物理学报,2010,53(8):1902-1913
[20]董春晖,王尚旭.变时间步长有限差分法逆时偏移[J].地球物理学进展,2010,25(4):1298-1305
[21]李信富,张美根.显式分形插值在有限元叠前逆时偏移成像中的应用[J].地球物理学进展,2008,23(5): 1406-1411
[22]陈可洋.一阶速度—应力Biot双相各向同性介质弹性波波场分离数值模拟[J].计算物理,201l,28(3): 404-412
[23]陈可洋.倾斜界面绕射波时距曲线特征及其应用[J].中国科学院研究生院学报,2011,28(2): 202-209
[24]陈可洋.时限时移相关法叠前逆时成像条件及其应用[J].石油物探,2011,50(1):22-26
[25]常旭,刘伊克,桂志先.反射地震零偏移距逆时偏移方法用于隧道超前预报[J].地球物理学报,2006,49 (5):1482-1488
[26]杜启振,秦童.横向各向同性介质弹性波多分量叠前逆时偏移[J].地球物理学报,2009,52(3):801-807
[27]Yoon K,Marfurt K J,Starr W.Challenges in reverse -time migration[J].Expanded Abstracts of 74~(th) Annual Internat SEG Mtg,2004,1057-1060
[28]Zhang Y,Sun J,Gray S.Reverse-time migration: amplitude and implementation issues[J].Expanded Abstracts of 77~(th) Annual Internat SEG Mtg,2007, 2145-2148
[29]Jones I F.Pre-processing considerations for reverse time migration[J].Expanded Abstracts of 78~(th) Annual Internat SEG Mtg,2008,2297-2301
[2]陈可洋.高阶弹性波波动方程正演模拟及逆时偏移成像研究[D].黑龙江大庆:大庆石油学院,2009
[3]陈可洋.标量声波波动方程高阶交错网格有限差分法[J].中国海上油气,2009,21(4):232-236
[4]陈可洋.地震波数值模拟中差分近似的各向异性分析[J].石油物探,2010,49(1):19-22
[5]陈可洋.声波完全匹配层吸收边界条件的改进算法[J].石油物探,2009,48(1):76-79
[6]杨微,陈可洋.加权吸收边界条件的优化设计[J].石油物探,2009,48(3):244-246,251
[7]陈可洋.边界吸收中镶边法的评价[J].中国科学院研究生院学报,2010,27(2):170-175
[8]陈可洋.完全匹配层吸收边界条件研究[J].石油物探,2010,49(5):472-477
[9]陈可洋.基于高阶有限差分的波动方程叠前逆时偏移方法[J].石油物探,2009,48(5):475-478
[10]陈可洋,杨微,吴清岭,等.几种地震波叠后深度偏移方法的比较[J].勘探地球物理进展,2009,32(4): 257-260
[11]陈可洋.各向异性弹性波动方程多分量联合叠后逆时偏移[J].内陆地震,2009,23(4):455-460
[12]陈可洋.地震波旅行时计算方法及其模型试验分析[J].石油物探,2010,49(2):153-157
[13]陈可洋.地震波逆时偏移方法研究综述[J].勘探地??球物理进展,2010,33(3):153-159
[14]陈可洋.声波和弹性波叠后逆时深度偏移[J].天然气勘探与开发,2010,33(3):20-21,49
[15]陈可洋.高阶交错网格有限差分法弹性波叠前逆时深度偏移[J].油气地球物理,2010,8(3):1-4
[16]刘红伟,李博,刘洪,等.地震叠前逆时偏移高阶有限差分算法及GPU实现[J].地球物理学报,2010,53 (7):1725-1733
[17]刘红伟,刘洪,邹振,等.地震叠前逆时偏移中的去噪与存储[J].地球物理学报,2010,53(9):2171-2180
[18]孙文博,孙赞东.基于伪谱法的VSP逆时偏移及其应用研究[J].地球物理学报,2010,53(9):2196- 2203
[19]杨仁虎,常旭,刘伊克.叠前逆时偏移影响因素分析[J].地球物理学报,2010,53(8):1902-1913
[20]董春晖,王尚旭.变时间步长有限差分法逆时偏移[J].地球物理学进展,2010,25(4):1298-1305
[21]李信富,张美根.显式分形插值在有限元叠前逆时偏移成像中的应用[J].地球物理学进展,2008,23(5): 1406-1411
[22]陈可洋.一阶速度—应力Biot双相各向同性介质弹性波波场分离数值模拟[J].计算物理,201l,28(3): 404-412
[23]陈可洋.倾斜界面绕射波时距曲线特征及其应用[J].中国科学院研究生院学报,2011,28(2): 202-209
[24]陈可洋.时限时移相关法叠前逆时成像条件及其应用[J].石油物探,2011,50(1):22-26
[25]常旭,刘伊克,桂志先.反射地震零偏移距逆时偏移方法用于隧道超前预报[J].地球物理学报,2006,49 (5):1482-1488
[26]杜启振,秦童.横向各向同性介质弹性波多分量叠前逆时偏移[J].地球物理学报,2009,52(3):801-807
[27]Yoon K,Marfurt K J,Starr W.Challenges in reverse -time migration[J].Expanded Abstracts of 74~(th) Annual Internat SEG Mtg,2004,1057-1060
[28]Zhang Y,Sun J,Gray S.Reverse-time migration: amplitude and implementation issues[J].Expanded Abstracts of 77~(th) Annual Internat SEG Mtg,2007, 2145-2148
[29]Jones I F.Pre-processing considerations for reverse time migration[J].Expanded Abstracts of 78~(th) Annual Internat SEG Mtg,2008,2297-2301
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