单孔洞缝模型超声波实验测试与分析

对储层（特别是碳酸岩储层）中大量发育的孔洞缝，提出了孔洞缝储层研究的物理模型模拟方法。根据物理模型相似性原则从缝洞系统中抽取制作了单孔洞缝物理模型，目的是探讨在缝洞系统中单个缝洞的大小、形状与地震属性参数之间的关系和变化规律以及与孔洞缝密度之间的关系。通过室内超声波实验，观测不同缝、洞密度物理模型的地震波特征响应，分析了缝、洞密度的变化及孔洞的尺寸、形状对地震波属性参数的影响，重点讨论了裂缝、孔洞密度与纵波属性的关系。实验表明，在受孔洞缝密度影响的地震波属性参数中，地震波振幅、主频率、品质因子Q的变化幅度普遍比速度高2个数量级，说明地震波的动力学参数比运动学参数对孔洞缝密度的变化更为敏感。这为利用地震波的动力学参数来检测地下岩层中孔洞缝的分布和发育带提供了实验依据。模型孔洞尺寸大小最大相差42倍，但地震波各属性参数在相同数量级中变化，同时体积相同形状不同的洞对地震波各属性参数的影响不明显，说明地震波各属性参数对孔洞缝密度敏感，而对孔洞缝的实际尺寸大小及形状不敏感。

Ultrasonic experiment and analysis of single fracture-cave physical model

A new simulating method is proposed to study the well devel- oped fracture-cave in reservoirs (especially in carbonate reservoir). According to the physical modeling similarity theory,the single fracture-cave physical models were extracted from the fracture-cave system to discuss how the size,shape,and density of a single frac- ture-cave are related with seismic attributes.Seismic responses to these physical models were observed by ultrasonic experiment using the MTS (Mechanics Test System).The effect of fracture-cave density and the size and shape of single fracture-cave on seismic P- wave attributes was analyzed.The experiment shows that in the seismic attributes influenced by fracture-cave density,the changes in amplitude,the main frequency,and the quality factor are two orders of magnitude higher than the velocity.The result indicates that the seismic dynamic parameters (amplitude,phase,attenua- tion etc.) are more sensitive to fracture-cave density than the kine- matic parameters (velocity etc.).Therefore,it is very effective to detect fracture-cave reservoir by using seismic dynamic attributes. The difference in cave size of the models may reach as high as 4200% but the seismic wave attributes change within the same or- der of magnitude.At the same time,the cave which is different in shape but has the same volume is not sensitive to the seismic wave attributes,showing that the seismic wave attributes are sensitive to fracture-cave density and insensitive to the actual size and shape of a single fracture-cave.