塔北哈拉哈塘地区奥陶系潜山岩溶储层发育特征及控制因素

Characteristics of karst reservoirs in the Ordovician buried hills of the Halahatang area,northern Tarim basin

哈拉哈塘地区奥陶系潜山岩溶缝洞型储层是哈拉哈塘油田的主力产层。通过对岩溶地质背景、区域构造分析,利用本区钻录井、薄片、岩芯等资料研究岩溶型储层特征,探讨储层分布规律及岩溶作用对储层的控制。结果表明哈拉哈塘地区奥陶系潜山岩溶储层的主体发育于一间房组和鹰山组。垂向上潜山区存在两套储层:上部表层岩溶带储层及下部径流溶蚀带储层。表层岩溶带储集类型主要为孔洞型和裂缝-孔洞型储层,主要受一间房组沉积末期的岩溶作用及桑塔木组沉积末期岩溶作用共同控制;径流溶蚀带储层类型主要为洞穴型、裂缝-孔洞型储层,岩溶缝洞系统以岩溶管道系统为主,储层形成受良里塔格期及桑塔木组沉积末期岩溶作用等多期岩溶作用控制。岩溶层组、岩溶作用期次、古地貌、古水系及断裂等控制了岩溶储层的分布发育,形成了复杂的缝洞体。

Crack-cavity type karst reservoirs, which lie in the Ordovician buried hills, are the primary production horizons of the Halahatang oil field northern Tarim basin. Based on karst geology background and tectonic evolution of this area, using integrated data of drilling-logging wells, thin slices and seismic surveys, this work analyzes the characteristics, spatial distribution, and controlling factors of the karst reservoirs in this area. The results show that these reservoirs are largely present in the Middle Ordovician Yijianfang formation and the Lower-Middle Ordovician Yingshan formation. In vertical direction, there are two sets of reservoirs in verti in the buried hills, which are the upper superficial dissolution belt and lower runoff dissolution belt. The superficial belt contains cavity type and crack-cavity type reservoirs, which are controlled by karstification at the ends of the deposition of both the Yijianfang and Sangtamu formations. The runoff type of reservoirs are of cavity and crack-cavity types, which are dominated by karst channel systems, determined by multiple episodes of karstification including the end Lianglitage period and end of the Sangtamu formation sedimentation. Many factors, such as the layers of karst, episodes of karstification, ancient landforms, ancient drainages and faults, jointly controlled the distribution of karst reservoirs, resulting in complicated crack-cavity systems in this area.