孔隙结构对干岩石弹性波衰减影响的数值模拟研究  

Numerical-modeling of pore structure effects on acoustic attenuation in dry rocks

作　　者：王子振[1] 王瑞和[1] 李天阳 单珣 邱浩[1] 

机构地区：[1]中国石油大学(华东)石油工程学院,青岛266580

出　　处：《地球物理学进展》2014年第6期2766-2773,共8页Progress in Geophysics

基　　金：国家自然科学基金(51274230);山东省自然科学基金(ZR2012EEL01);中央高校基本科研业务费专项资金(14CX02040A;14CX06023A);中国石油大学(华东)优秀博士学位论文培育计划项目联合资助

摘　　要：根据弹性波动力学及相似性理论,采用数值模拟方法研究了孔隙结构对干岩石弹性波衰减的影响.结果表明:孔隙随机均匀分布比规则均匀分布引起的散射衰减更强;孔隙长轴与波传播方向夹角0°时衰减系数最小,90°时衰减系数最大,夹角随机分布时衰减系数介于二者之间.在孔隙密度不变时,衰减系数随纵横比的增大呈指数规律增大,并主要为吸收衰减增大.在纵横比不变时,衰减系数随孔隙密度的增大而呈幂函数规律增大;但不同的孔隙密度变化方式影响衰减的机制不同,孔隙数目增大使岩石的吸收衰减增大,而孔隙尺寸增大使岩石的散射衰减增大.这为基于弹性波响应预测岩石的孔隙结构提供了依据.Based on the elastic wave theory and similarity principle,the pore structure effects on acoustic attenuation coefficient in dry rocks were simulated.The calculation results indicate that the scattering attenuation caused by uniformly random distributed pores is stronger than that of regular distributed pores.When the angle between the pore major axis and the wave propagation direction is randomly valued,the attenuation coefficient is in between the minimum with 0°and maximum with 90°. The attenuation coefficient increases exponentially with the increase of aspect ratio at the same pore density,which is mainly contributed by the increase of absorbing attenuation.The attenuation coefficient increases as apower function as the pore density increases at the same aspect ratio.But the mechanism of attenuation is not the same for different changing patterns of pore density.The absorbing attenuation increases when the pore density increased by more pore numbers.However,the scattering attenuation increases when the pore density increased by larger pore size.These results lay a foundation for pore structure prediction from elastic wave responses.

关 键 词：孔隙结构 衰减系数 弹性波 相似性原理 数值模拟 

分 类 号：P631[天文地球—地质矿产勘探]