地层条件下砂岩含水饱和度对波速及衰减影响的实验研究

An experimental study of influence of water saturation on velocity and attenuation in sandstone under stratum conditions

为了研究含气地层对地震波传播的影响,在地层温压条件下,用超声波测试了长庆油田苏里格气田砂岩样品在不同饱和度下的纵、横波速度和衰减Q值.实验表明砂岩样品的物性和流体含量对纵波的速度和衰减的影响均大于横波,含气饱和度大于60%时纵波Q值变化明显;物性越好,含气饱和度越高,纵波Q值越小,吸收越大.分析实验结果和相应的影响机理,给出了利用纵波的吸收衰减预测砂岩含气性的应用实例.

To study the influence of the gas saturata to seismic wave propagation, at the temperature and pressure of stratum, the velocity and attenuation Q of primary and share waves in Changqing sandstone samples are measured under different saturation degrees by ultrasonic. The result shows that under the high frequency condition, fluid contents in sandstone samples have nearly no effect on share wave velocity, but affects obviously primary wave velocity; and the relation between fluid content and wave attenuation is different for S-wave and Pwave. The analysis to the experiment result and the corresponding influence mechanism is made, and an application example is presented.