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地震波是研究地球内部物质成分和结构最有效的工具之一.鉴于哈密地区油田对砂岩地震波性质研究的需求,本文在室内利用Autolab2000岩石物性测试设备,开展干燥、饱水及饱油条件下,砂岩X、Y、Z三个正交方向的弹性波速测试,得到不同压力下纵横波速随含水饱和度的变化规律,并在不同含水饱和度下分析了动态弹性常数(E和υ).结果表明:(1)波速与压力呈对数关系,相关系数在0.96以上;纵波速度与含水饱和度呈正相关,但随压力的增加,其增加速率会减小;横波速度在低压下基本不受含水饱和度影响,但随压力增加,其与含水饱和度呈负相关.(2)砂岩Z(垂直)方向波速最小;横波各向异性小于纵波;不同压力下,纵横波各向异性都是干燥大于饱油,并皆大于饱水状态.(3)恒定含水饱和度时,杨氏模量和泊松比皆随围压增加而增加,低压下(小于80 MPa,约3 km深度)增加速度快,而高压下(大于80 MPa)增速变缓;相同围压下,泊松比随含水饱和度增加而增加,而杨氏模量则有增有减.
Seismic waves are one of the most effective tools for studying the composition and structure of the Earth’s interior materials.In view of the need of research on the properties of sandstone seismic waves in the Hami area, Autolab2000 petrophysical testing equipment is used indoors to carry out experiments on sandstone X, Y and Z. The dynamic elastic constants (E and υ) under different water saturations were analyzed.The results showed that: (1) (1) The relationship between wave velocity and pressure is logarithmic, and the correlation coefficient is above 0.96. The P-wave velocity is positively correlated with water saturation, but the increase rate decreases with the increase of pressure. S-wave velocity is not affected by water saturation at low pressure (2) the wave velocity in the direction of Z (vertical) of sandstones is the smallest; the shear wave anisotropy is smaller than that of the longitudinal wave; under different pressures, the anisotropy of longitudinal and shear waves is more than that of the saturated oil (3) At constant water saturation, the Young’s modulus and Poisson’s ratio both increase with the increase of confining pressure, and the increase rate is faster under low pressure (less than 80 MPa, about 3 km depth), while the high pressure under( Greater than 80 MPa) slowed down; under the same confining pressure, the Poisson’s ratio increased with the increase of water saturation, while the Young’s modulus increased and decreased.