摘要
高地层水矿化度的深层—超深层致密砂岩气藏开发过程中盐析及其诱发问题日益突出。选取了致密砂岩柱塞岩心,开展了盐析前后岩心孔渗参数测试实验,利用扫描电镜观察了结晶盐在岩心孔喉内的盐晶形态和赋存状态,并通过压汞法分析了盐析前后致密岩心孔喉半径分布变化情况。结果表明,盐析后致密砂岩孔渗出现明显降低,孔隙度降幅最高可达53%,渗透率降幅最高为65%;结晶盐在致密砂岩孔喉内的赋存状态可分为沿着粒间孔缝和天然微裂缝团簇生长、附着在伊/蒙间层等亲水性黏土矿物表面层状生长以及在孔隙角隅处单粒生长3种模式;当结晶盐颗粒尺寸越接近致密砂岩孔径分布时,盐析越容易造成裂缝和孔喉堵塞。基于致密砂岩气藏盐析诱发损害现象,建议孔隙度小于5%的致密砂岩在开展室内分析实验前应进行洗盐预处理。
Salt precipitation and its induced problems are increasingly prominent with the development of deep and ultra-deep tight sandstone gas reservoirs with high salinity formation water.In this paper,the change of porosity and permeability of a series of tight sandstone was measured,and then the morphology and occurrence state of crystalloid salt within the pore was observed by SEM.Meanwhile,the changes of pore size distribution were analyzed by high-pressure mercury injection.Experimental results show that salt precipitation has a great effect on the porosity and permeability,which decrease by 53% and 65% after salt precipitation,respectively.The occurrence state of the crystalloid salt can be divided into three models：Superposition growth along with the intergranular pore-fractures/natural micro-fractures,lamellar growth attached to the surface of the hydrophilic mineral like I/S interstratified mineral and the individual particles located in the corner of pore.When the size of crystalloid salt is closer to the pore size distribution of tight sandstone,it is easier to cause cracks and pore throat blockage.It is suggested that salt wash pretreatment should be carried out before analysis of tight sandstone with porosity less than 5%.
作者
游利军
王哲
康毅力
张杜杰
You Li-jun;Wang Zhe;Kang Yi-li;Zhang Du-jie(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu 610500,China)
出处
《天然气地球科学》
EI
CAS
CSCD
北大核心
2018年第6期866-872,共7页
Natural Gas Geoscience
基金
非常规油气层保护四川省青年科技创新研究团队项目(编号:2016TD0016)
国家自然科学基金项目(编号:51674209)联合资助
关键词
盐析
致密砂岩
孔隙度
渗透率
储层损害
Salt precipitation
Tight sandstone
Porosity
Permeability
Formation damage
作者简介
游利军（1976-），男，河南洛阳人，教授，博士，主要从事储层保护、非常规天然气、岩石物理研究与教学工作．E—mail：youlj0379@126．com．
