轮南-巴楚地区奥陶系生物礁储层特征

ORDOVICION REEF IN LUNAN-BACHU AREA AND THEIR RESERVOIR CHARACTERISTICS

塔里木盆地轮南巴楚地区奥陶系生物礁赋存于中奥陶统一间房组和上奥陶统桑塔木组 ,主要造礁生物为瓶筐石 ,其次为海绵类、苔藓虫类和有柄棘皮动物类。礁体规模较小 ,形态多样 ,礁体一般由礁基、礁核和礁盖三部分组成。含礁层系储层物性总体比较差 ,以低孔低渗或低孔中渗为特征 ,但是礁基、礁盖储层物性明显好于礁体本身。礁体储层类型为裂缝型或孔隙裂缝型储层 。

Ordovicion reef in Lunan-Bachu area of Tarim basin have been discovered recently in Middle Ordovicion Yi Jianfang Formation and Upper Ordovicion Sang Tama Formation.The reef-build-up organism are mainly composed of Calathium,Lithistida,Batostoma and Archaeoscyphia etc.The reef body,small in size and variety in type,is generally made up of reef base,reef core and reef cap.Characterized by low-porosity-low permeability or low porosity-middle permeability based on the analysis of porosity and permeability,rocks of reef reservoir are not good in general,but the porosity of reef base and reef cap is higher than that of reef core.The reservoirs,controlled by sedimentary structure and diagenesis,are mainly in types of fracture and pore-fracture.