塔中Ⅰ号坡折带上奥陶统礁滩型储层发育特征及其主控因素

Characteristics and main controlling factors of the Upper Ordovician reef-bank reservoir development in the Tazhong I slope-break zone

塔中Ⅰ号坡折带上奥陶统发育大型台缘礁滩复合体,具有小礁大滩的结构特征,多旋回礁滩体纵向多期加积叠置、横向复合连片。静态和动态资料表明礁滩复合体基质孔隙度低,属低孔特低渗储层,以孔洞-裂缝型、洞穴型、孔洞型储层为主,次生的溶蚀孔洞和构造裂缝是礁滩复合体最有效的储、渗空间。研究表明,有利沉积相带是礁滩型储层发育的基础,优质储层主要沿台缘礁滩相展布,岩溶作用和构造作用是古老碳酸盐岩储集性能改善的关键,所形成的大型缝洞系统是油气高产稳产的主要原因。

The huge reef-bank complexes developed in the Upper Ordovician along the Tazhong Ⅰ slope-break zone feature in large areas of shoals and small size of reefs, and vertical multistage accretion and overriding of muhicycle reef-bank and lateral connection as a whole. Static and dynamic data indicate low matrix porosity of the complex, suggesting a reservoir with super low permeability. The reef-bank complex also developed cavity-fracture reservoirs, cavern reservoirs and cavity reservoirs. The secondary dissolution cavities and structural fractures are the most effective reservoir and flow space. The researches show that the favorable sedimentary facies belt is the foundation for the formation of reef-bank reservoirs, high-quality reservoirs mainly distribute along the reef-bank facies belt on the edge of platform, karstification and tectonism are essential for improving the poroperm characteristics of the ancient carbonate reservoirs, and the large fracture-vug systems formed by these factors contribute most to the high and stable production of oil and gas.