S-wave attenuation in porous media is affected by the presence and properties of saturating fluids. We measured the ultrasonic S-wave velocities of three types of tight rocks (siltstone, dolomite, and sandstone) under partial fluid saturation conditions using the pulse-transmission technique. The S-wave attenuation is estimated by the centroid frequency shift and spectral-ratio methods. The fluid-saturated test results show that the attenuation of most water-saturated dolomites is stronger than that of gas- or oil-saturated dolomites, whereas no apparent relationship exists between attenuation and fluid type in siltstone. The attenuation of siltstone and dolomite increases with increasing porosity and permeability, as well as with clay content for siltstone with clay contents less than 6%. The maximum attenuation of rocks partially saturated with gas and water occurs at high water saturation (55%–100%) in most siltstones. The attenuation of most dolomites shows an increasing trend with water saturation, but remains nearly unchanged in partially saturated sandstone. The attenuation of rocks partially saturated with oil and water is strongest at the partial saturation state in siltstone, but remains essentially constant with water saturation in dolomite. A squirt flow model is used to predict the S-wave attenuation of the fluid-saturated sample. Based on rock property and microstructure analyses, wave attenuation in the fluid-saturated rocks measured in this study can be explained by squirt flow mechanisms and the scattering effect owing to heterogeneities of water patches and grain clusters.

多孔介质中的 S 波衰减受饱和流体的存在和性质的影响。我们使用脉冲传输技术测量了在部分流体饱和条件下三种致密岩石（粉砂岩、白云岩和砂岩）的超声波 S 波速度。S波衰减通过质心频移和频谱比方法估计。流体饱和测试结果表明，大多数水饱和白云岩的衰减比气或油饱和白云岩强，而衰减与流体类型之间没有明显的关系。粉砂岩。粉砂岩和白云岩的衰减随着孔隙度和渗透率的增加而增加，粘土含量小于6%的粉砂岩随粘土含量的增加而增加。在大多数粉砂岩中，部分饱和气和水的岩石的最大衰减发生在高含水饱和度（55%–100%）时。大多数白云岩的衰减随着含水饱和度的增加而增加，但在部分饱和的砂岩中几乎没有变化。部分饱和油水岩石的衰减在部分饱和状态最强在粉砂岩中，但随着白云岩中的水饱和度基本保持不变。喷射流模型用于预测流体饱和样品的 S 波衰减。基于岩石性质和微观结构分析，本研究中测量的流体饱和岩石中的波浪衰减可以通过喷射流机制和由于水斑和颗粒簇的异质性引起的散射效应来解释。