摘要
基于Hudson理论制作了具有不同裂缝密度、不同裂缝张开度和不同裂缝延伸度的三组物理模型,使用超声波透射法采集了三组模型的纵波振幅数据。文中对比、分析了实验结果与Hudson理论结果,并利用频谱比法计算了三组模型的品质因子,通过分析纵波振幅和品质因子的变化判断不同模型的衰减特性,得出以下认识:①随着裂缝密度的增大,总体上实测纵波振幅呈幅度很小的下降趋势,并显示出较强的振幅方位各向异性,且实验结果与Hudson理论结果类似,因此应用Hudson理论研究裂缝密度较准确。②随着裂缝延伸度的增大,总体上实测纵波振幅呈现增大趋势,且在X和Z方向振幅变化趋势基本相同;而Hudson理论结果的纵波振幅呈幅度很小的单调下降趋势,Hudson理论结果与实验结果的差异说明Hudson理论对于裂缝延伸度的预测存在问题。③随着裂缝张开度的增大,实测纵波振幅变化明显,实测结果的纵波振幅变化幅度远大于Hud-son理论结果,说明Hudson理论公式低估了裂缝张开度对地震波能量的影响。④速度各向异性和衰减各向异性随不同裂缝参数的变化趋势相同,其中裂缝张开度对各向异性的影响最为明显,衰减各向异性的数值要比速度各向异性的数值大一个数量级以上,表明衰减各向异性对裂缝参数的变化更加敏感。
Three sets of physical models are built based on Hudson theory with different fracture density,aperture and length.Test amplitudes of P-wave on the models are recorded by the pulse transmission method.Experimental data are compared with theoretical data from Hudson theory and quality factor Q of models are obtained using classic spectral ratio method for determining attenuation.The study results show:①With the increase of fracture density,amplitude has a little decrease and azimuthal amplitude anisotropy.By the analysis of comparing results,it can be seen that Hudson theory's prediction is exact.②With the increase of fracture length,amplitude increases in the mass and the situation is similar in X and Z directions.But the prediction of Hudson theory is different with small decrease.③With the increase of fracture opevture,the variation of amplitude is much bigger than the prediction,which means that the theory underestimate the effect of fracture length.④The anisotropy of velocity and amplitude changes similarly with different fracture parameters.The influence of fracture aperture is most obvious and attenuation anisotropy is more sensitive to the change of fracture parameter than velocity anisotropy.
出处
《石油地球物理勘探》
EI
CSCD
北大核心
2012年第5期728-734,753,共8页
Oil Geophysical Prospecting
基金
国家科技重大专项(2011ZX05019-008-03)资助
