摘要:
页岩气是目前国内外非常规油气领域研究的热点,有效的页岩孔隙度值是评价页岩储层物性的重要参数。由于页岩本身具有易碎的特点,导致钻取柱体样品难度大,很多学者采用碎样法计算孔隙度,但碎样法与柱体法的差别及测定结果的有效性并未见相关研究成果。本文对相同样品通过三种不同方法:氦气膨胀法测孔隙度(柱体),真、视密度法及低温氮气吸附实验法(样品粉碎至40~60目)分别计算孔隙度。结果发现三种方法测定的三组孔隙度数值不同,每种方法在样品制备上及实验方法的差别是影响实验结果的主要因素,为检验三组孔隙度值的有效性,采用数理统计中的单因素方差分析法进行分析,结果表明页岩柱体与粉碎至40~60目范围内的页岩样品测量的孔隙度值虽有差别,但在有效范围内,具有一致性。但是将页岩粉碎后,页岩中的有效孔隙变化程度较大,故用柱体测定的有效孔隙度法优于其他两种碎样方法。
Abstract:
The study of gas shale is the hot spot in unconventional oil and gas resources exploration at home and abroad. The effective porosity of shale is an important parameter to access the reservoir property which is always the bottleneck problem and difficulty in reservoir description. It is difficult to drill a perfect cylinder from the weathered and breakable shale. Many people comminuted the samples to different sizes to get the shale porosity by measuring bulk density and skeletal density and nitrogen adsorption method. But no validated difference and effectiveness of the results between the cylinder and broken samples measurement have been shown until now. We chose twelve shale cylinders and broke the samples around the cylinders to 40~60 mesh, measurements were conducted with the three methods above, respectively. The results showed that three groups of values were different, they may be mainly controlled by experiment parameters and sample integrity. One-way analysis of variance in mathematical statistics was adopted to analyse the effectiveness of the results from the three measurement methods. Mathematical analysis showed cylinder porosity by gas expansion method and broken sample porosity in 40~60 mesh by density method and nitrogen adsorption method had no marked difference, they were consistent and effective. But, a large number of effective porosity will be destroyed in the process of crushing the samples. Overall, effective porosity measured by cylinder method is superior to the other two.
点击查看大图
下载:
