川东地区中二叠统茅口组白云岩储层成因机理及主控因素

利用露头和岩心资料，通过大量的薄片、扫描电镜和主量元素、微量元素、稀土元素、锶同位素等分析化验资料，深入分析川东地区中二叠统茅口组白云岩储层成因机理，取得3个方面的新认识：①根据晶粒结构及其产状将白云岩进一步细分为三大类，基质镶嵌状白云岩，距构造热液脉相对较远；基质“雾心亮边”白云岩，多与构造热液脉体伴生；构造裂缝白云岩，主要分布在热液破裂形成的张性构造裂缝和孔洞中，半充填；②白云岩主要经历2期白云化改造，均为热液成因，其中基质镶嵌状白云岩形成于同沉积及浅埋条件下，而基质“雾心亮边”白云岩是在早期白云化作用的基础上，后期受到了强烈的热液改造作用形成，构造裂缝白云岩则是由热液流体沉淀形成；③浅滩是白云岩发育的基础，基底断裂为同沉积断裂，且为富镁热液的运移通道，是白云岩“似层状”展布的关键，明确了15^#基地断裂南侧为白云岩勘探首选目标区。

Genetic mechanism and main controlling factors of the Middle Permian Maokou Formation dolomite reservoirs in the eastern Sichuan Basin

Based on outcrop and core data， a large number of thin section， scanning electron microscope， major element， trace element， rare earth element and strontium isotope analysis data， the formation mechanism of dolomite reservoir of Maokou Formation in eastern Sichuan was analyzed， and three new understandings were obtained： （1） According to the grain structure and occurrence， the dolomite can be further divided into three categories： matrix mosaic dolomite， which is relatively far from the tectonic hydrothermal veins. The matrix "mist core and bright edge" dolomite is mostly associated with the tectonic hydrothermal veins. The structural fracture dolomite is mainly distributed in the tensional tectonic fractures and pores formed by hydrothermal fracture， and is half-filled.（2）The dolomite has undergone two stages of hydrothermal dolomitization. The matrix mosaic dolomite was formed under syndepositional and shallow buried conditions， and the "mist core bright edge" dolomite was formed on the basis of early dolomitization and later hydrothermal reformation. The tectonic fracture dolomites were formed by hydrothermal fluid precipitation.（3）The shoal was the basis of dolomite development， and the basement faults were synsedimentary fault and the migration channels of hydrothermal fluids， which was the key to the formation of dolomite. The south side of the 15^# base fault is the preferred target area for dolomite exploration， which provides reference for the Maokou Formation in Sichuan Basin.