疏松砂岩油藏注水开发声波速度的影响因素

Influential factors of acoustic velocity in the course of waterflood development of unconsolidated sandstone reservoir

由于疏松砂岩声波纵、横波速度的影响因素较多,因此有必要对各影响因素进行定量研究。在模拟地层条件下直接对岩心进行饱和、驱替试验,建立不同的油、水饱和度,并在驱替过程中进行了纵、横波速度的连续测试。结果表明:水驱至含水饱和度极限时,岩心纵波速度平均增加7.4%左右,横波速度基本不变;在水驱过程中,由于岩石骨架发生变化,岩石变得疏松,致使岩心纵波速度降低3.1%左右,因此水驱至含水饱和度极限时,最终的岩心纵波速度只增加4.3%左右;对于注水效果好的稀油油藏,温度及压力对声波速度的影响较弱,但是对于地层能量补充不充分的区块及稠油油藏,温度及压力对声波速度的影响不能忽略。

Because there are many influential factors in experiment of acoustic velocity testing of unconsolidated sandstone, quantitative study is short of the influential factors. The core saturating and displacing experiments were done in the same core under the simulated reservoir conditions. Various water and oil saturation degree was established. And continuous measurements of compressional velocity and shear velocity were made in the course of displacing. The results show that the compressional velocity increases averagely about 7.4% because of the changing of saturation degree in the course of waterflood. Because of the changing of rock skeleton in the course of waterflood, compressional velocity decreases about 3.1%. The final compressional velocity increases about 4.3% , and shear velocity is unchangeable when water saturation degree changes. Temperature and pressure effects are weak to acoustic velocity for thin oil reservoir with efficient waterflood. But temperature and pressure effects must be considered for heavy oil reservoir and the block in which its producing energy cannot be compensated sufficiently.