塔中西部奥陶系鹰山组古岩溶特征及主控因素

为明确塔中西部奥陶系鹰山组古岩溶储层发育及主控因素,总结鹰山组古岩溶特征及发育条件,划分了岩溶层组类型。在鹰山组古地貌恢复基础上,通过钻井、取心、测井等资料,分析丘状岩溶台地、上丘状岩溶缓坡地和下丘状岩溶缓坡地典型井岩溶缝洞特征。结合大量钻井资料分析了上述3类古地貌单元岩溶缝洞储层发育规律及主控因素。对岩溶缝洞储层发育深度分析表明,岩溶缝洞发育段主要在鹰山组顶面以下0~180 m,受3期海平面控制,发育多层缝洞。表层溶洞主要发育在0~50 m,泥质充填较强,测井GR值较高,溶洞规模多小于2 m。岩溶台地区岩溶缝洞形成受微地貌、水动力条件控制,以小规模溶洞、溶蚀孔洞、溶蚀裂缝为主,缝洞后期易充填。岩溶缓坡地岩溶缝洞形成受岩溶层组、水动力条件控制,以小溶蚀孔洞、溶蚀裂缝为主,后期不易充填。滨岸岩溶带及岩溶岛屿发育海水、混合水岩溶作用,溶蚀作用及冲蚀、侵蚀作用使该区域形成较大洞穴。

Karst Development Law and Main Controlling Factors of the Ordovician Yingshan formation in Western Tazhong

In order to clarify the development of karst reservoirs and the main controlling factors in the Yingshan Formation of Ordovician in the central and Western Tarim Basin, the characteristics of the development of the ancient karst fracture-cave system in the Yingshan Formation in the central and Western Tarim Basin are analyzed.Control the development of multi-layer fracture and cave system.The surface caves are mainly developed in the 0~50 m range,muddy fill,logging GR value is high,and the size of the cave is much less than 2 m.The main controlling factors include karst formation, palaeo karst landform,three stage shoreline and fault.The karst mechanism of different karst geomorphic units is analyzed. The formation of karst fracture and cave in Karst platform area is controlled by micro-geomorphology and hydrodynamic conditions.The karst fracture and cave mainly consist of small-scale karst cave, karst cave as well as karst fracture and cave,which are easy to fill in the later stage of fracture and cave.The karst cave is mainly composed of small dissolution pores and corrosion cracks,and is not easy to fill in later stage. Coastal karst zone and karst islands develop seawater karstification and mixed water karstification. The karstification,erosion and erosion make the area easy to form larger caves.