川西雷口坡组碳酸盐岩储层特征及成岩作用

川西雷口坡组储层较发育,(藻)砂屑白云岩、中-细晶白云岩为主要储集岩,粒间溶孔、粒内溶孔为主要孔隙类型,孔隙结构以中-小孔细喉为主,总体显示出低孔低渗的特征。雷口坡组(藻)砂屑白云岩在川西坳陷的西缘分布稳定,厚度较大,总体上以海底、埋藏成岩环境为主,北段受到大气水成岩环境的影响,向南逐渐减弱。受成岩环境的控制,雷口坡组(藻)砂屑白云岩主要的成岩作用类型有压实、压溶作用、胶结充填作用、溶蚀作用、白云岩化作用等,其中,建设性的成岩作用主要有溶蚀作用、白云岩化作用、晚期破裂作用。溶蚀作用中的准同生期暴露溶蚀、表生溶蚀,主要分布于川西坳陷北部中坝构造带附近;而埋藏溶蚀作用对于川西坳陷中、南段储层的发育也具有非常重要的意义。鲕粒、砂屑白云岩主要与早期回流渗透、埋藏白云岩化有关。综合沉积、成岩特征,雷口坡组在川西坳陷北段南部砂屑滩体发育,且经历了准同生期大气水溶蚀、表生期溶蚀和埋藏溶蚀作用,是最有利的勘探区;而在中段的金河剖面的鲕粒、砂屑白云岩粒间(溶)孔中,发现有大量的沥青,表明发生过油气的运移或聚集,也是值得重视的有利勘探区域。

A study on characteristics and diagenesis of carbonate reservoirs in the Middle Triassic Leikoupo Formation in western Sichuan Depression

Reservoirs are relatively well-developed in the Leikoupo Formation of western Sichuan Depression. They are mainly algal dolorenite and medium-fine crystalline dolostone reservoirs with intergranular and intragranular dissolution pores.The pore structures are dominated by medium-fine pore throat.As a whole,these reservoirs are low in both porosity and permeability.Thick algal dolorenite reservoirs in the Formation distribute widely in western margin of the Basin.As a whole,the reservoirs were formed in seabe...