致密砂岩气层的弹性阻抗正演模拟研究
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摘要
以苏里格气田盒8砂岩的实际井统计资料为基础建立致密砂岩气层的岩石物理模型,通过流体替代进行弹性阻抗正演模拟,分析弹性阻抗对致密砂岩气层识别的流体敏感性特征及其正演模型的响应趋势。研究表明,四类致密砂岩气层表现出各不相同的弹性阻抗特征,即Ⅰ类气层表现为随入射角增大而减小的正高弹性阻抗差特征,Ⅱ类气层表现为随入射角增大而减小且由正到负转换的近零弹性阻抗差特征,Ⅲ类气层表现为随入射角增大而减小的负高弹性阻抗差特征,Ⅳ类气层表现为随入射角增大而增大的负高弹性阻抗差特征;Ⅰ、Ⅱ、Ⅲ类气层的弹性阻抗都随入射角的增大而减小,盖层的弹性阻抗都随入射角的增大而增大,以致反射系数都随入射角的增大而减小,而Ⅳ类气层和盖层的弹性阻抗随入射角的增大分别呈增大和减小趋势,以致反射系数随入射角的增大而增大;四类致密砂岩气层的弹性阻抗和反射系数都随含气饱和度的增大呈减小趋势,其中在含气饱和度为0~0.1之间的减小幅度较大。此外,弹性阻抗正演模型的振幅响应特征能较好地反映出弹性阻抗随入射角和含气饱和度的变化关系,这种响应特征可为弹性阻抗反演结果的含气性解释提供指导。
In order to analyze fluid sensitivity characteristics of elastic impedance for tight sandstone gas reservoir identification and its model response trend,an elastic impedance modeling in tight sandstone gas reservoir is conducted.Based on well data statistics of He 8sandstone in Sulige Gasfield,rock physical model of tight sandstone gas reservoir is established and used in fluid replacement simulation to do the modeling. As the study shows,four types of elastic impedance characteristics for gas reservoirs have been found:Class Ⅰ,positive high elastic impedance difference decreases with incident angle increase;ClassⅡ,near zero elastic impedance difference decreases from positive to negative with incident angle increase;ClassⅢ,negative high elastic impedance difference decreases with incident angle increase;and Class Ⅳ,negative high elastic impedance difference increases with incident angle increase.For Classes Ⅰ,Ⅱ,andⅢ,the elastic impedance of reservoirs decreases and that of cap rocks increases with incident angle increase while the reflection coefficient decreases with incident angle increase.But for ClassⅣ,the elastic impedance of reservoirs increases and that of cap rocks decreases with incident angle increase while the reflection coefficient increases with incident angle increase.The elastic impedance and reflection coefficients of the four types of tight gas sandstone reservoirs all show a decreasing trend with gas saturation increase.Larger decreases appear with gas saturation range between 0and0.1.In addition,amplitude response characteristics of elastic impedance model can well reflect elastic impedance variation with incident angle and gas saturation,which can serve as a guide for tight gas sandstone reservoir prediction.
In order to analyze fluid sensitivity characteristics of elastic impedance for tight sandstone gas reservoir identification and its model response trend,an elastic impedance modeling in tight sandstone gas reservoir is conducted.Based on well data statistics of He 8sandstone in Sulige Gasfield,rock physical model of tight sandstone gas reservoir is established and used in fluid replacement simulation to do the modeling. As the study shows,four types of elastic impedance characteristics for gas reservoirs have been found:Class Ⅰ,positive high elastic impedance difference decreases with incident angle increase;ClassⅡ,near zero elastic impedance difference decreases from positive to negative with incident angle increase;ClassⅢ,negative high elastic impedance difference decreases with incident angle increase;and Class Ⅳ,negative high elastic impedance difference increases with incident angle increase.For Classes Ⅰ,Ⅱ,andⅢ,the elastic impedance of reservoirs decreases and that of cap rocks increases with incident angle increase while the reflection coefficient decreases with incident angle increase.But for ClassⅣ,the elastic impedance of reservoirs increases and that of cap rocks decreases with incident angle increase while the reflection coefficient increases with incident angle increase.The elastic impedance and reflection coefficients of the four types of tight gas sandstone reservoirs all show a decreasing trend with gas saturation increase.Larger decreases appear with gas saturation range between 0and0.1.In addition,amplitude response characteristics of elastic impedance model can well reflect elastic impedance variation with incident angle and gas saturation,which can serve as a guide for tight gas sandstone reservoir prediction.
引文
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[14]李爱山,印兴耀,陆娜等.两个角度弹性阻抗反演在中深层储层含气预测中的应用.石油地球物理勘探,2011,41(1):87-92.Li Aishan,Yin Xingyao,Lu Na et al.Application of elastic impedance inversion with two angle stack gathers to predict gas-bearing reservoir of mid-deep layer.OGP,2009,44(1):87-92.
[15]牛聪,刘春成,刘志斌等.扩展弹性阻抗反演在储层预测中的应用.石油地球物理勘探,2011,46(增刊1):67-71.Niu Cong,Liu Chuncheng,Liu Zhibin et al.Applications of EEI inversion in reservoir prediction.OGP,2011,46(S1):67-71.
[16]高刚,贺振华,曹俊兴等.两项式弹性波阻抗反演方法在深层碳酸盐岩储层预测中的应用.石油地球物理勘探,2013,48(3):450-457.Gao Gang,He Zhenhua,Cao Junxing et al.The new two-term elastic impedance inversion and its application to predict deep gas-bearing carbonate reservoirs.OGP,2013,48(3):450-457.
[17]Aki K,Richards P.Quantitative Seismology—Theory and Method.W H Freemall Company,New York,1980.
[18]Castagna J P,Swan H W.Framework for AVO gradient and intercept interpretation.Geophysics,1998,63(3):948-956.
[19]Gassmann F.Uber die Elastizitat poroser Medien.Vierteljahrsschrift der Naturforschenden Gesellschaft in Zurich,1951,96:1-23.
[20]郭栋,吴国忱.基于弹性波阻抗理论的岩性参数提取方法及应用.油气地球物理,2008,6(1):16-20.Guo Dong,Wu Guochen.The method and application of lithology parameter extraction based on elastic wave impedance.Petroleum Geophysics,2008,6(1):16-20.
[2]董晓霞,梅廉夫,全永旺.致密砂岩气藏的类型和勘探前景.天然气地球科学,2008,18(3):351-354.Dong Xiaoxia,Mei Lianfu,Quan Yongwang.Types of tight sand gas accumulation and its exploration prospect.Natural Gas Geoscience,2008,18(3):351-354.
[3]邹才能,陶士振,侯连华等.非常规油气地质.北京:地质出版社,2011,50-71,86-92.Zou Caineng,Tao Shizhen,Hou Lianhua et al.Unconventional Petroleum Geology.Beijing:Geological Publishing House,2011:50-71,86-92.
[4]黄伟传,杨长春,范桃园等.岩石物理分析技术在储层预测中的应用.地球物理学进展,2007,22(6):1791-1795.Huang Weichuan,Yang Changchun,Fan Taoyuan et al.The application of petrophysical analysis in the reservoir prediction.Progress in Geophysics,2007,22(6):1791-1795.
[5]潘仁芳,陈思路,张利萍等.含气砂岩AVO正演的半定量分析.石油地球物理勘探,2013,48(1):103-108.Pan Renfang,Chen Silu,Zhang Liping et al.Semiquantitative analysis of gas bearing sand by AVO forward modeling.OGP,2013,48(1):103-108.
[6]Connolly P.Elastic impedance.The Leading Edge,1999,18(4):438-452.
[7]Whitcombe D N.Elastic impedance normalization.Geophysics,2002,67(1):60-62.
[8]倪逸.弹性阻抗计算的一种新方法.石油地球物理勘探,2003,38(2):147-150,155.Ni Yi.A new method for calculation of elastic wave impedance.OGP,2003,38(2):147-150,155.
[9]马劲风.地震勘探中广义弹性阻抗的正反演.地球物理学报,2003,46(1):118-124.Ma Jinfeng.Forward modeling and inversion method of generalized elastic impedance in seismic exploration.Chinese Journal of Geophysics,2003,46(1):118-124.
[10]甘利灯,赵邦六,杜文辉等.弹性阻抗在岩性与流体预测中的潜力分析.石油物探,2005,44(5):504~508.Gan Lideng,Zhao Bangliu,Du Wenhui et al.The potential analysis of elastic impedance in the lithology and fluid prediction.GPP,2005,44(5):504-508.
[11]张奎,倪逸.三种弹性波阻抗公式比较.石油地球物理勘探,2006,41(增刊):7-11.Zhang Kui,Ni Yi.Comparison among three elastic wave impedance formulas.OGP,2006,41(S):7-11.
[12]王浩,罗兵,李霆.弹性阻抗对比分析.岩性油气藏,2010,22(3):110-113.Wang Hao,Luo Bing,Li Ting.Comparative analysis of elastic impedance.Lithologic Reservoirs,2010,22(3):110-113.
[13]王保丽,印兴耀,张繁昌.基于Gray近似的弹性波阻抗方程及反演.石油地球物理勘探,2007,42(4):435-439.Wang Baoli,Yin Xingyao,Zhang Fanchang.Gray approximation-based elastic wave impedance equation and inversion.OGP,2007,42(4):435-439.
[14]李爱山,印兴耀,陆娜等.两个角度弹性阻抗反演在中深层储层含气预测中的应用.石油地球物理勘探,2011,41(1):87-92.Li Aishan,Yin Xingyao,Lu Na et al.Application of elastic impedance inversion with two angle stack gathers to predict gas-bearing reservoir of mid-deep layer.OGP,2009,44(1):87-92.
[15]牛聪,刘春成,刘志斌等.扩展弹性阻抗反演在储层预测中的应用.石油地球物理勘探,2011,46(增刊1):67-71.Niu Cong,Liu Chuncheng,Liu Zhibin et al.Applications of EEI inversion in reservoir prediction.OGP,2011,46(S1):67-71.
[16]高刚,贺振华,曹俊兴等.两项式弹性波阻抗反演方法在深层碳酸盐岩储层预测中的应用.石油地球物理勘探,2013,48(3):450-457.Gao Gang,He Zhenhua,Cao Junxing et al.The new two-term elastic impedance inversion and its application to predict deep gas-bearing carbonate reservoirs.OGP,2013,48(3):450-457.
[17]Aki K,Richards P.Quantitative Seismology—Theory and Method.W H Freemall Company,New York,1980.
[18]Castagna J P,Swan H W.Framework for AVO gradient and intercept interpretation.Geophysics,1998,63(3):948-956.
[19]Gassmann F.Uber die Elastizitat poroser Medien.Vierteljahrsschrift der Naturforschenden Gesellschaft in Zurich,1951,96:1-23.
[20]郭栋,吴国忱.基于弹性波阻抗理论的岩性参数提取方法及应用.油气地球物理,2008,6(1):16-20.Guo Dong,Wu Guochen.The method and application of lithology parameter extraction based on elastic wave impedance.Petroleum Geophysics,2008,6(1):16-20.