贝尔凹陷沉凝灰岩储层片钠铝石前体矿物研究

为拓展CO2封存的储层选取范围,研究CO2充注过的储层中矿物的赋存状态,通过薄片鉴定、扫描电镜分析、X--射线衍射分析及铸体图像分析等技术对贝尔凹陷含片钠铝石储层进行了系统研究。研究区发育片钠铝石的岩石类型为沉凝灰岩,储层深度范围为882.26~941.4 m,该类储层发育有2类9种储集空间类型,以次生孔隙为主,属于低孔低渗储层。岩石骨架碎屑颗粒石英、长石、岩屑均有不同程度溶蚀;自生矿物以片钠铝石、铁白云石和菱铁矿为主。片钠铝石主要以充填溶蚀孔隙或交代颗粒的形式产出。综合研究区岩相学、矿物含量和热力学分析结果,长石和片钠铝石的生成具有亲缘性,为片钠铝石的形成提供了必要的元素和生长空间。

Research on precursor mineral of dawsonite in tuffite of Beier Depression

In the aim of exploiting the range of CO2 storage reservoirs and researching occurrence of CO2 fillings in the reservoirs,the authors studied the dawsonite-bearing of Beier Depression sandstone.It is mainly formed by tuffite at the locations of 882.26 ～941.4 m in the studied area.Reservoir spaces can be divided into 9 types of 2 categories dominated by secondary pores,and the reservoir is low in porosity and permeability.The rock skeletons containing quartz,feldspar and lithic,all have dissolution in different degrees.Authigenic minerals are dominated by dawsonite,ankerite and siderite.Dawsonite output in form of filling pores or replacement of other minerals.According the comprehensive petrography,mineral content and thermodynamic analysis in the studied area,the feldspar has affinity with dawsonite in the formation and provides the necessary elements,and growing space.