含气饱和度对致密砂岩纵波速度影响的实验研究及应用

Experimental study and application on effect of gas saturation on P-wave velocity

本文为探索声波速度和含气饱和度之间的关系,对取自鄂尔多斯盆地致密砂岩层的岩心在不同的含气饱和度下进行了纵波速度的测量,结果表明:(1)岩心含水饱和时的的纵波速度要比含气饱和时的大;(2)含气饱和度大于70%时,纵波速度对含气饱和度的变化反映不敏感,或随着含气饱和度的增大略有增加,含气饱和度小于70%时,纵波速度随着含气饱和度增大近似成线性降低;(3)该实验研究为声波测井数据指示气层奠定了一定的理论基础,为致密砂岩层气层的识别提供了依据;(4)本文建立了纵波速度随着含气饱和度变化而变化的关系式,并将之应用到致密砂岩层含气饱和度的评价中,评价效果良好.这为导电性评价饱和度失效时,评价致密砂岩气层提供了新的方法.

In this paper P-wave velocity of core samples from Ordos Basin tight sandstone reservoirs is measured at different gas saturation to establish the relationship between acoustic velocity and gas saturation and the results show ：（1）The Pwave velocity of core saturated aqueous is larger than that of core saturated gas.（2）P-wave velocity does not change obviously or increases slightly with the increasing gas saturation when it is greater than 70%.And when the gas saturation is less than 70%,the P-wave velocity almost decreases linearly with increasing gas saturation.（3）This experimental study lays a groundwork for indication reservoirs with acoustic logging data and provides the basis for identification of tight sand reservoirs.（4）In this paper,a formula between P-wave velocity and gas saturation is founded and then applied in evaluation of gas saturation in tight sandstone reservoirs.And the evaluation result is good.It provides new methods for evaluation tight sandstone reservoirs when calculating saturation from resistivity fails.