恒速与恒压压汞差异及其在储层评价中的应用

The Difference between Constant-rate Mercury Injection and Constant-pressure Mercury Injection and the Application in Reservoir Assessment

阐述了恒速压汞和恒压压汞的原理方法,通过实际岩样的测试分析,比较了2种不同方法的优缺点和适用范围,分析了实验压力对实验结果的影响。恒压压汞测试速度快、实验压力高、可测试孔隙介质的孔径范围广,适宜于大量的生产及科研样品测试;恒速压汞测试速度非常慢,可区分给出孔隙与喉道的不同参数,能更加精确地表征多孔介质的孔隙结构,但目前恒速压汞仪的实验压力相对较低,可测试样品的孔径范围有限,对致密岩样测试获取的参数信息不全面。建议研究者在选用不同方法时,需要提前了解岩样的孔隙分布范围,确定合理的实验压力,一般来说,致密砂岩基质渗透率低于1×10-3μm2以下,对恒速压汞就应慎重使用,而进行恒压压汞时则应增大实验压力,以获得更具代表性的孔隙特征参数。

The theory and method of constant-rate mercury injection and constant-pressure mercury injection is discussed in the paper. Through the testing and analysis of field rock sample, the difference between con- stant-rate mercury injection and constant-pressure mercury injection advantages and disadvantages and range of application was contrast, and the impact of experiment pressure on the experiment result is ana- lyzed. The characteristics of constant-pressure mercury injection are fast speed, high experiment pressure and wind range pore radius. So it is suitable to test the majority of samples which are used in production and research. The testing speed of constant-rate mercury injection is very slow,and it can provide parame- ters of pore and throat and characterize the pore structure of porous medium. The experimental pressure of constant-rate mercury injection is low,so the testing sample pore radius range is small and tight rock pa- rameters are incomplete. The scientific researcher should learn the pore radius range of rock sample and de- termine a reasonable experimental pressure before choosing the mercury injection method. In general, the permeability of tight rock sample is lower than 1 × 10-3^μm2 ,so the constant-rate mercury injection should be used carefully. In order to acquire more representative pore characteristic parameters, the experimental pressure of constant-pressure mercury injection should be as big as possible.