柴达木盆地东部石炭系致密灰岩孔渗特征

发布时间：2018-02-17 08:26

本文关键词： 致密灰岩表观渗透率滑脱流扩散流柴达木盆地东部　出处：《中国岩溶》2017年01期 　论文类型：期刊论文

【摘要】：碳酸盐岩储层孔隙系统复杂。对空隙结构特征、渗流机理的研究直接影响到油气资源的勘探和开采。本研究选取了柴达木盆地东部地区ZK5-2钻井中石炭系的5块致密灰岩样品,通过XRD、XRF技术对灰岩的矿物成分、化学成分进行定量测试;利用氦气双室法与孔径分布实验(包括压汞法、氮气吸附法、二氧化碳吸附法)确定灰岩的孔隙度与空隙的孔径分布;用CH_4、N_2、CO_2、He四种气体进行渗流实验确定灰岩的表观渗透率。研究结果表明:致密灰岩的表观渗透率与其孔隙度没有明显的关系。表观渗透率由达西流、滑脱流与扩散流三部分组成,表观渗透率大小按CH_4、N_2、CO_2、He的顺序依次增加,其中He所测得的表观渗透率明显高于其他三种气体。滑脱流对表观渗透率的贡献受到分子平均自由程与孔径的双重控制,当气体分子平均自由程与岩石内集中出现的孔径接近时,在这些相近孔径的孔隙中会出现明显滑脱现象,此时滑脱流将对表观渗透率产生较大的贡献。分子平均自由程较大的气体在致密灰岩中主要以扩散的形式运移。岩石孔径小于分子平均自由程的孔隙所占比例越大,扩散流对表观渗透率的贡献度越高。
[Abstract]:The pore system of carbonate reservoir is complex. The study of pore structure and percolation mechanism has a direct influence on the exploration and exploitation of oil and gas resources. In this study, five samples of Carboniferous dense limestone in ZK5-2 drilling in the eastern part of Qaidam Basin are selected. The mineral composition and chemical composition of limestone were measured quantitatively by XRD- XRF technique, the pore size distribution of limestone was determined by helium double chamber method and pore size distribution experiment (including mercury injection method, nitrogen adsorption method, carbon dioxide adsorption method). The apparent permeability of the dense limestone is determined by the percolation experiment with the gas Ch _ 4N _ 2CO _ 2He. The results show that the apparent permeability of the dense limestone has no obvious relationship with its porosity. The apparent permeability is composed of three parts: Darcy flow, slippage flow and diffusion flow. The apparent permeability increases in the order of Ch _ 4N _ 2C _ 2C _ 2He, in which the apparent permeability measured by he is obviously higher than that of the other three gases. The contribution of slippage to the apparent permeability is controlled by the molecular average free path and pore size. When the average free path of gas molecules is close to the pore size concentrated in the rock, there will be obvious slippage in the pores of these similar pore sizes. The gas with larger molecular average free path is mainly transported in the form of diffusion in dense limestone. The larger the pore size of rock is less than the molecular average free path, the larger the proportion of pores is. The contribution of diffusion flow to apparent permeability is higher.
【作者单位】：中国地质大学(北京)水资源与环境学院;中国地质科学院地质力学研究所;
【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(DD20160173)
【分类号】：P618.13

【相似文献】