川东下侏罗统自流井组页岩储层特征及勘探潜力评价

摘要

通过对侏罗系自流井组页岩层系的岩心和野外露头观察、薄片鉴定、氩离子抛光、扫描电镜、压汞和气体吸附等手段,研究了页岩层系的岩石类型及储层微观类型和特征.页岩层系的岩石类型以黑色页岩为主,黑色页岩储层以矿物质粒间残留孔为主,微裂缝和有机质孔发育较少,孔隙度分布在1.4％ ～ 4.9％,孔隙结构以直径小于100 nm的孔隙为主,占85％以上.与研究区海相页岩相比,陆相侏罗系页岩微观储层有机质气孔较少、孔隙度较小且孔喉直径也较小.在勘探上,考虑到侏罗系大面积和全层系油气显示以及页岩油气在个别地区的突破,建议在侏罗系页岩(烃源岩)厚度较大和成熟度较高的区域开展研究.这些地区具有较好的页岩油气形成物质基础和储集条件,在紧邻页岩的致密砂岩或灰岩也可能具有致密油气或常规圈闭油气成藏的良好条件.%Through core and outcrop observation,thin section examination,argon-ion milling,scanning electronic microscope and mercury data et al,this paper studied the shale rock types,Microscopic types and characteristics of the Jurassic Ziliujing Formation.The reservoirs are dominated by black shale which mainly developed interparticle pores,the micro fractures and the organic matter pores are less developed.The shale porosity is between 1.4 ％-4.9 ％ and the nanoscale micro-pores with diameter less than 100 nm account for more than 85 ％ of total porosity.Compared with the marine shale gas reservoir in the study area,the organic matter pores are less porous and pore diameters are smaller in the Jurassic shale gas reservoir.Considering the large area and thick interval with oil/gas show of the Jurassic shale,and the success of shale oil/gas exploration in some spots,the favorable areas are suggested where the shales (source rocks) are thick and thermal maturity is high.These places may have good source charge and reservoir quality as shale oil and gas reservoirs.The tight sandstone or limestone in the vicinity of the shale may also have good possibility for hydrocarbon accumulation of tight oil or conventional reservoir.