塔中地区顺9井区柯坪塔格组黏土膜成因及其油气地质意义

Origin and petroleum geological significance of clay minerals membrane in sandstones of Kepingtage formation,well Shun 9,Tarim basin

为寻觅致密砂岩储层中发育的优质储层提供理论依据,分析铸体薄片鉴定、扫描电镜资料、结合压汞及物性资料.结果表明:塔里木盆地塔中顺9井区志留系柯坪塔格组沥青砂岩中发育的黏土矿物薄膜形成于成岩早期(同生成岩期),以自生式为主,含少量原生式黏土膜;黏土膜的发育与分布受到沉积作用、成岩环境及成岩温压系统的共同控制,早成岩期(同生期)发育的黏土膜在中—低压实强度下对储层的孔隙保护具有一定的建设性作用,因其占据一定的孔喉空间,又降低储层的渗透率,随着埋深增大,黏土膜矿物成分也逐渐向伊利石转化并分布在孔隙中,伊利石赋存状态也由蜂窝状变为毛发状、丝网状及搭桥状,分割甚至堵塞孔隙,使得储层砂体渗透率大幅度降低;沉积环境中的沉积微相对黏土膜发育与分布的控制体现在中—下临滨微相中黏土膜较为常见,而在上临滨—前临滨微相中,因水体的淘洗降低储层砂体中的泥质含量,黏土膜不发育,储层砂体中的黏土膜含量制约储层质量,发育黏土膜的井段储层孔隙度大于不发育黏土膜的井段,黏土膜含量在0.5%～5.0%井段的储层孔隙度要好于黏土膜含量超过5.0%井段的.

To provide a theoretical basis for quality reservoir prediction from tight sandstone,in this paper,the authors study in Causes and petroleum geological significance of clay minerals membrane,in sandstones of Kepingtage Formation well Shun 9 in the Tarim Basin,from thin section identification under microscope,scanning electron microscopy(SEM),impressing hydrargyrum and porosity and permeability data,the research shows that clay minerals membrane divided into original cause and self-enerating cause,among them with self-enerating cause for most.Clay minerals membrane usually comes into being in earlier diagenetic stage(or developing together diagenetic stage),its development and distribution was commonly controled by environments of sedimentation,diagenetic and temperature and pressure of the diagenetic systems,earlier diagenetic stage development clay minerals membrane strength of reservoir porosity protection has a constructive role at the moderate pressure,while its occupy some pore throat space,but also reduces the permeability of the reservoir as the depth increases.Clay membrane mineral composition gradually transformed to illite and distributed in the pores,illite mode of occurrence from the honeycomb into a hair-like mesh-like and bypass shaped,split or even blocked pore,so that the reservoir sand bodies penetration and large amplitude decreases.Sedimentary facie effect for clay minerals membrane development and distribution that it have more in under shore face but deficiency in former the shore face micro phase,the clay minerals membrane content restricts the reservoir sand bodies in reservoir quality,developmental clay film hole section reservoir porosity greater than not developed well clay film segment,clay minerals membrane content in reservoir porosity of 0.5%~5.0% of the well section is better than clay membrane content of more than 5.0% of the well section.