利用Hudson裂隙模型分析井径变化对声波测井响应的影响

裂隙性介质因其复杂的结构和可观的藏储量一直是资源勘查领域的重点研究对象。基于Hudson裂隙理论对裂隙介质中不同裂隙参数（数密度、角度、纵横比）下变化井径的井场响应进行数值模拟，得到如下结果：在裂隙数密度较小的情况下，纵波、横波以及斯通利波幅度对井径变化响应较敏感；在裂隙角度较大的情况下，斯通利波幅度对井径变化响应较敏感；在裂隙角度较小的情况下，横波幅度对井径变化响应较敏感；在裂隙纵横比较小的情况下，纵波、横波以及斯通利波幅度对井径变化响应较敏感；在频率-波数二维谱中，随着井径的增大，波动激发强度峰值所在的频率带以及波动的首次激发频率都向低频区域移动。由此认为：弹性波在裂隙性介质中传播时在受井径变化的影响下产生规律性响应，应用Hudson裂隙理论模拟裂隙介质的井场响应可以系统地分析裂隙参数和井径变化对声波传播规律的影响，进而指导实地裂隙储层声波测井勘探工作。

Using Hudson Cracked Medium to Analyze Acoustic Logging Response of Different Well Diameter

Complex structure of cracked media has been a key research resource prospecting object due to the fact that it hides huge reserves. Based on Hudson’s crack theory, responses of different well diameters in cracked medium with different crack parameters (number density, angle and aspect ratio) are simulated. Results show that when crack number density is small, compressional, shear and Stoneley wave amplitudes are sensitive to the variation of well diameter; when the crack angle is big, Stoneley wave amplitude is sensitive to the variation of well diameter; when the crack angle is small, shear wave amplitude is sensitive to the variation of well diameter; when crack aspect ratio is small, compressional, shear and Stoneley wave amplitudes are sensitive to the variation of well diameter; in two-dimensional spectrum the multi-mode wave’s initial excitation frequency becomes smaller as well diameter increases; the frequency band of the maximum excitation intensity will move to low frequency as well diameter increases. It is clear that the propagation of elastic wave in cracked medium is affected by well diameter and crack parameters, and obeys certain regularity. Applying Hudson’s crack theory to simulate the cracked medium at well-site can be used to systematically analyze the well-site response of cracked media. The results of this study can give a guide for field logging work in the case of cracked media.