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声波测井资料是评价储层物性特征和识别气层及水层的主要方法之一。在中高孔隙度储层中普遍使用的纵波速度估算砂岩孔隙度的威利公式,在低孔、低渗储层岩石中由于受到孔隙中的流体及压力和温度的影响适用性变差。通过开展岩石物理实验,研究了矿化度、流体饱和度及地层条件等参数对岩石纵、横波速度的影响。结果表明:在250kHz~1MHz超声频率范围内,在干燥或饱水状态下,横波频散度都不大于3%,可以忽略不计;纵波速度随含水饱和度的变化明显,横波速度随含水饱和度变化不大;压实作用会使岩石的纵波速度快速增加,横波速度缓慢增加;在高温高压下,纵、横波速度随含水饱和度的变化更为平缓,温度和矿化度对地层声波速度的测量可以忽略不计。该实验可以有效指导应用声波测井资料评价储层物性特征及应用纵、横波速度比识别气层。
Acoustic logging data is one of the main methods to evaluate reservoir physical properties and identify gas and water layers. The Willie formula for estimating sandstone porosity, which is commonly used in medium- and high-porosity reservoirs, is less applicable due to fluid and pressure and temperature in the pores in low-porosity and low-permeability reservoirs. Through the experiment of rock physics, the influence of salinity, fluid saturation and formation conditions on the longitudinal and shear wave velocities of rock is studied. The results show that in the frequency range of 250kHz ~ 1MHz, the frequency of transverse wave dispersion is not more than 3% under the dry or saturated water condition. The longitudinal wave velocity changes obviously with the water saturation, and the shear wave velocity changes with the water saturation The compressional action will make the P-wave velocity increase rapidly and the S-wave velocity increase slowly; Under high temperature and high pressure, the longitudinal and transverse S-wave velocities change more gently with the water saturation. The influence of temperature and salinity on the acoustic velocity of the formation The measurement is negligible. The experiment can effectively guide the application of acoustic logging data to evaluate reservoir physical properties and the application of longitudinal and shear-wave velocity ratios to identify gas reservoirs.