通过压制共散射点道集映射噪声改善绕射波成像分辨率
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摘要
碳酸盐岩缝洞型储层的地震反射表现为复杂的绕射波特征,因此提高绕射波成像精度对储层描述与刻画非常重要。基于等效偏移距叠前时间偏移方法,根据绕射波映射到共散射点(CSP)道集后的特征,利用信号倾角分解方法压制映射相干噪声,以减轻其对绕射波成像横向分辨率的影响。鉴于绕射波与映射相干噪声信息的有效分离是关键,提出了一种适应振幅空变的信号分解算法,理论试算验证了该方法的有效性。
For carbonate fracture-cave reservoirs,seismic reflections display as complex diffraction,so it is important to improve imaging accuracy of diffraction for reservoir description.Based on the equivalent -offset prestack time migration method,according to the features of diffraction mapped onto CSP gathers,the mapped coherent noise from equivalent-offset transformation was suppressed by signal dip decomposition method to eliminate its impact on the lateral resolution of diffraction imaging.Since the effective sorting of diffraction and mapping of coherent noise is the key step,an improved signal decomposition method suitable to amplitude space-variant was proposed.Theoretical testing proved its feasibility.
For carbonate fracture-cave reservoirs,seismic reflections display as complex diffraction,so it is important to improve imaging accuracy of diffraction for reservoir description.Based on the equivalent -offset prestack time migration method,according to the features of diffraction mapped onto CSP gathers,the mapped coherent noise from equivalent-offset transformation was suppressed by signal dip decomposition method to eliminate its impact on the lateral resolution of diffraction imaging.Since the effective sorting of diffraction and mapping of coherent noise is the key step,an improved signal decomposition method suitable to amplitude space-variant was proposed.Theoretical testing proved its feasibility.
引文
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[2]Landa E,Keydar S.Seismic monitoring of diffraction images for detection of local heterogeneities[J].Geophysics, 1998,63(3):1093-1100
[3]Khaidukov V.Diffraction imaging by a focusing-defocusing approach[J].Expanded Abstracts of 73~(rd) Annual Internat SEG Mtg,2003,26-31
[4]Nowak E J,Imhof M G,Tech V.Diffractor localization via weighted Radon translations[J].Expanded Abstracts of 74~(th) Annual Internat SEG Mtg,2004, 10-15
[5]王华忠,徐蔚亚,徐兆涛,等.DMO和叠前时间偏移的共同起点[J].石油地球物理勘探,2002,37(3): 224-229
[6]Neidell N S.Perceptions in seismic imaging part 2: reflective and diffractive contributions to seismic imaging [J].The Leading Edge,1997,16(8):1121-1123
[7]Hubral P,Schleicher J,Tygel M.A unified approach to 3-D seismic reflection imaging,partⅠ:basic concepts [J].Geophysics,1996,61(3):742-758
[8]Hubral P,Schleicher J,Tygel M.A unified approach to 3-D seismic reflection imaging,partⅡ:theory[J]. Geophysics,1996,61(3):759-775
[9]Bancroft J C,Geigerz H D,Margra G F.The equivalent offset method of prestack time migration[J]. Geophysics,1998,63(6):2042-2053
[10]Margrave G F,Bancroft J C,Geiger H D.Fourier prestack migration by equivalent wavenumber[J]. Geophysics,1999,64(1):197-207
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