基于叠前道集小波域Q值求取方法研究
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摘要
地层Q值是用于油气检测的重要参数,针对应用叠后地震资料求取Q值存在多解性的问题,探索了基于叠前道集求取Q值的QVO(地震品质因子Q随偏移距变化)方法,进行了数值模型试算和实际地震资料的应用,结果证明了QVO方法的正确性和有效性。该方法首先利用小波变换将经过动校正处理的CMP道集进行时频域转换,通过选择不同的时窗和与之相对应的尺度因子,利用小波域谱比法计算非零偏移距频谱比斜率值;然后根据频谱比斜率值随偏移距的变化关系,求得零偏移距处的Q值。模型试算提取的频谱比斜率与偏移距平方近似呈线性关系,与理论吻合,证实了理论的正确性。将QVO方法应用于实际工区地震资料提取地层Q值,结果表明,含气区与非含气区的Q值差异明显,含气区的Q值较低,表现为强吸收。与叠后地震资料提取的Q值相比,QVO方法提取的Q值精度高,更能真实地反映地层吸收特征,提高了储层含气性检测的精度。
The Q value of formation is an important parameter of oil and gas detection.According to the ambiguity for Q computation by post-stack seismic data,we discussed the Q versus offset(QVO) method which extracts Q value through pre-stack gathers.Firstly, the CMP gathers after DMO were carried out time-frequency transform; by selecting different time window and corresponding scale factors,the slope of non-zero offset spectral ratio was calculated by spectral ratio method in wavelet domain.Then,in terms of the variation relationship between slope and offset,we calculated the Q value of zero offset.By model testing,we discovered that the extracted curve of slope and offset square is approximate linear,which is coinciding with the theory and proves the correction of the theory.In addition,the QVO method was used to extract Q of actual formation, and the result shows that the difference of Q between gasbearing area and non-gas area is obvious.In gas-bearing area,the Q is relatively low,which displays strong absorption.The precision of Q computed by QVO method is higher that from post-stack seismic data,which can reflect the actual absorption of the formations and improve the accuracy of gas prediction.
The Q value of formation is an important parameter of oil and gas detection.According to the ambiguity for Q computation by post-stack seismic data,we discussed the Q versus offset(QVO) method which extracts Q value through pre-stack gathers.Firstly, the CMP gathers after DMO were carried out time-frequency transform; by selecting different time window and corresponding scale factors,the slope of non-zero offset spectral ratio was calculated by spectral ratio method in wavelet domain.Then,in terms of the variation relationship between slope and offset,we calculated the Q value of zero offset.By model testing,we discovered that the extracted curve of slope and offset square is approximate linear,which is coinciding with the theory and proves the correction of the theory.In addition,the QVO method was used to extract Q of actual formation, and the result shows that the difference of Q between gasbearing area and non-gas area is obvious.In gas-bearing area,the Q is relatively low,which displays strong absorption.The precision of Q computed by QVO method is higher that from post-stack seismic data,which can reflect the actual absorption of the formations and improve the accuracy of gas prediction.
引文
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[12]郑江峰.粘弹性介质中提高地震资料分辨率方法研究[D].黑龙江:大庆石油学院,2006
[13]赵伟,葛艳.利用零偏移距VSP资料在小波域计算介质Q值[J].地球物理学报,2008,51(4): 1202-1208
[14]首皓,孙鲁平,刘红伟,等.复杂介质地震波场模拟的单程波方法[J].石油物探,2009,48(5):479-482
[1 5]张璐,白晓寅.单程波法地震波衰减特征数值模拟分析[J].物探化探计算技术,2009,31(6):541-547
[16]熊晓军,贺振华,黄德济.起伏地表的单程波动方程地震叠前正演[J].天然气工业,2007,27(1):44-46
[2]黄花香,邓瑛,吴战培,等.吸收系数反演在川东碳酸盐岩储层预测中的应用[J].石油物探,2003,42(1): 86-88
[3]郭栋,韩文功,王兴谋,等.地层吸收特征参数分析预测深层气藏方法[J].油气地球物理,2008,6(3): 20-24
[4]文瑞霞.用频率衰减属性预测庆深气田火山岩储层含气性[J].天然气工业,2009,29(8):26-29
[5]边树涛,董艳蕾,郑浚茂.地震波频谱衰减检测天然气技术应用研究[J].石油地球物理勘探,2007,42 (3):296-300
[6]宫同举,孙成禹,彭洪超,等.几种提取品质因子方法的对比[J].勘探地球物理进展,2009,32(4): 252-256
[7]辛可锋,李振春,王永刚,等.地层等效吸收系数反演[J].石油物探,2001,40(4):14-20
[8]刘财,刘洋,王典,等.一种频域吸收衰减补偿方法[J].石油物探,2005,44(2):116-118
[9]马昭军,刘洋.地震波衰减反演研究综述[J].地球物理学进展,2005,20(4):1074-1082
[10]王辉.用于岩体质量评价的地震波Q值计算方法[J].工程地质学报,2006,14(5):699-702
[11]Dasgupta R,Clark R A.Estimation of Q from surface seismic reflection data[J].Geophysics,1998,63 (6):2120-2128
[12]郑江峰.粘弹性介质中提高地震资料分辨率方法研究[D].黑龙江:大庆石油学院,2006
[13]赵伟,葛艳.利用零偏移距VSP资料在小波域计算介质Q值[J].地球物理学报,2008,51(4): 1202-1208
[14]首皓,孙鲁平,刘红伟,等.复杂介质地震波场模拟的单程波方法[J].石油物探,2009,48(5):479-482
[1 5]张璐,白晓寅.单程波法地震波衰减特征数值模拟分析[J].物探化探计算技术,2009,31(6):541-547
[16]熊晓军,贺振华,黄德济.起伏地表的单程波动方程地震叠前正演[J].天然气工业,2007,27(1):44-46
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