歧口凹陷深层地震岩石物理特征分析及应用

Analysis and application of seismic rock physical character for deep formation in Qikou depression

为明确歧口凹陷深层的岩石物理及AVO响应特征,分析歧口地区全波测井资料,优选该区敏感岩石物理参数;根据分岩性拟合求取纵横波转换经验公式,并采用流体置换原理进行叠前地震道集正演后提取AVO属性.结果表明:泊松比、纵横波速度比为该区有利储层预测的敏感参数,含气砂岩与含水砂岩的数值范围差异明显;歧口深层AVO响应特征可划分为3类:第一类是与气层相对应的反射振幅随着偏移距的增大而负向急剧增大;第二类是与油气同层相对应的反射振幅随着偏移距的增大而负向缓慢增大;第三类是与油水层及干层相对应的反射振幅随着偏移距的增大而负向减小.该结果可为歧口凹陷深层开展流体预测可行性提供依据.

In order to identify the character of rock physics and AVO attributes in the deep formation of Qikou depression,we carried out the analysis of full wave logging data and sensitive rock physical parameter optimization.The P-S wave conversion empirical formula for different lithology was achieved.Based on the fluid replacement and pre-stack seismic gathers forward modeling,AVO attributes were extracted.The result shows that Poisson's ratio and P-S wave velocity ratio parameter can be used to recognize the favorable reservoir and the data rang of water sand and gas sand differ obviously.The AVO response character for deep formation in QIKOU depression can be classified into three categories.The first class of AVO feature is that the reflection amplitude negative increase sharply with offset increasing,which correspond to gas sand.The second class of AVO feature is that the reflection amplitude negative increase slowly with offset increasing,which correspond to gas and oil sand.The third class of AVO feature is that the reflection amplitude negative decrease with offset increasing,which correspond to oil and water sand.The research result provides a theoretical basis to carry out the feasibility of c fluid prediction in Qikou depression.