非饱和低渗砂岩突破压力试验研究——以柴达木盆地东部石炭系砂岩为例

发布时间：2018-03-12 09:22

本文选题：突破压力　切入点：孔隙结构　出处：《水文地质工程地质》2017年06期 　论文类型：期刊论文

【摘要】：突破压力是气藏开采和盖层评估中的重要参数。文章选取柴达木盆地东部石炭系低渗砂岩岩心3块,对每块岩心进行6个不同含水率下的突破压力试验。通过XRD、XRF分析方法对砂岩的矿物成分、化学成分进行定量测试;利用氦气双室法与压汞试验对砂岩的孔隙度和孔径分布特征进行分析;用CH4气体模拟渗流试验对砂岩的绝对渗透率进行分析。结果表明:研究区低渗砂岩孔隙度在9.02%~10.96%之间,平均孔隙半径在0.1082~0.3709μm之间,绝对渗透率在0.008~0.012 m D之间,干岩石突破压力值在0.05~0.19 MPa之间,饱和岩石突破压力值在1.51~2.73 MPa之间。黏土矿物遇水膨胀对孔隙结构不会造成显著性改变,因此对突破压力没有明显影响。影响突破压力的主要因素是孔隙结构和含水率。试验结果表明突破压力与岩石孔隙大小之间呈现负相关的关系,随着平均孔径和中值半径的增大,突破压力随之降低。本研究得到了突破压力与含水率之间的定量函数关系:突破压力随含水率增加呈指数函数形式增加。
[Abstract]:Breakthrough pressure is an important parameter in gas reservoir exploitation and caprock assessment. This paper selects three low permeability sandstone cores of Carboniferous in the eastern Qaidam Basin. The breakthrough pressure tests were carried out on each core under six different water contents. The mineral composition and chemical composition of sandstone were measured quantitatively by XRDX XRF analysis method. The porosity and pore size distribution characteristics of sandstone were analyzed by means of helium dual-chamber method and mercury injection test, and the absolute permeability of sandstone was analyzed by CH4 gas simulation seepage test. The results showed that the porosity of low-permeability sandstone in the study area was between 9.02% and 10.96%. The mean pore radius is between 0.1082 渭 m and 0.3709 渭 m, the absolute permeability is 0.008 ~ 0.012 mm D, the breakthrough pressure of dry rock is 0.05 ~ 0.19 MPa, and the breakthrough pressure of saturated rock is 1.511 ~ 2.73 MPa. Therefore, there is no obvious effect on breakthrough pressure. The main factors affecting breakthrough pressure are pore structure and water content. The experimental results show that breakthrough pressure has a negative correlation with rock pore size. The breakthrough pressure decreases with the increase of mean aperture and median radius. The quantitative functional relationship between breakthrough pressure and water content is obtained: the breakthrough pressure increases with the increase of water content in the form of exponential function.
【作者单位】：中国地质大学(北京)水资源与环境学院;
【基金】：国家自然科学基金项目(40772208,41272387) 中国地质调查局地质调查项目(DD2016173)
【分类号】：TE311

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