苏25区块含水饱和度变化所引起的AVO响应分析
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摘要
岩石的流体饱和度是影响地震波振幅随炮检距变化(AVO)的重要因素。通过改变岩石含水饱和度来分析AVO响应特征。利用Gassmann方程对含气地层进行流体替代,计算了不同含水饱和度地层中的纵、横波速度,分析其变化规律,然后利用实际资料建立正演模型,并提取相应的泊松比剖面进行分析。研究表明,当含水饱和度从0%变化到80%时,随着入射角增加,振幅强度变化较小;当含水饱和度超过80%后,随着入射角增加,振幅强度变化较大。总之,随着含水饱和度的增加,振幅增加的强度总体上呈减小趋势。
Fluid saturation is the important factor inducing the seismic amplitude variation with offset(AVO).The AVO response characteristics are analyzed by changing the water saturation in the rock.The Gassmann equation for fluid substitution in gas-bearing strata is used,the velocities of pressure wave and shear wave are calculated for different water saturation strata,its variation rules are analyzed,and then the forward model is established by actual data,the corresponding Poisson's ratio profiles are studied.AVO response analysis shows that when the water saturation is changed between 0% to 80%,the increase of intensity of reflected wave amplitude with the increasing of the incident angle is stronger;when the water saturation is beyond 80%,the increase of intensity of the amplitude becomes very weak.In short,as water saturation increases,the increase strength of the reflected wave amplitude decreases on the whole.
Fluid saturation is the important factor inducing the seismic amplitude variation with offset(AVO).The AVO response characteristics are analyzed by changing the water saturation in the rock.The Gassmann equation for fluid substitution in gas-bearing strata is used,the velocities of pressure wave and shear wave are calculated for different water saturation strata,its variation rules are analyzed,and then the forward model is established by actual data,the corresponding Poisson's ratio profiles are studied.AVO response analysis shows that when the water saturation is changed between 0% to 80%,the increase of intensity of reflected wave amplitude with the increasing of the incident angle is stronger;when the water saturation is beyond 80%,the increase of intensity of the amplitude becomes very weak.In short,as water saturation increases,the increase strength of the reflected wave amplitude decreases on the whole.
引文
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[2]邹新宁,孙卫.盒8地层岩石物理参数及地震响应模型研究[J].中国石油大学学报(自然科学版),2006,30(2):21-25.
[3]郝晓红,王闯,谢春雨.流体替代技术及引用分析[J].海洋石油,2008,28(3):1-5.
[4]夏红敏,王尚旭,李生杰.含气地层的AVO响应分析[J].石油物探,2006,45(4):357-361.
[5]殷八斤,曾灏.AVO技术的理论与实践[M].北京:石油工业出版社,1995.
[6]马中高,管路平,贺振华,等.利用模型正演优选地震属性进行储层预测[J].石油学报,2003,24(6):35-39.
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