构造对塔中奥陶系礁滩型储集层的控制作用

塔中Ⅰ号坡折带上奥陶统台缘带的构造与储集层地质综合分析表明,缺乏改造作用的奥陶系古老礁滩体只能形成低孔低渗储集层,构造作用控制了高产油气储集层的发育。良里塔格组台缘礁滩体沉积末期,东部构造抬升形成强烈的暴露岩溶作用,发育大型溶洞,造成东部储集层优于西部。断裂带是地震剖面上具有“串珠”响应的大型缝洞发育的主体部位,埋藏期溶蚀形成的缝洞体主要受控于断裂。裂缝对后期溶蚀作用及储集层渗透性具有建设性作用,也是油气高产的重要因素。塔中Ⅰ号坡折带构造的差异性造成礁滩体的分布、储集层的发育具有分段性:东部台缘带高陡狭长,风化壳岩溶与构造作用形成的缝洞储集层发育,有利于油气高产稳产;西部断裂欠发育区台缘带宽缓,以孔隙型储集层为主。

Tectonic Controlling Factors Of Ordovician Reef and Bank Reservoir in Tazhong Uplift in Tarim Basin

The analysis of structure and reservoir along Tazhong No.1 belt in the northern Tazhong uplift of Tarim basin shows that in the Ordovician reef and bank without reconstruction there only exists low-porosity and low-permeability reservoir, and the tectonic action controls the development of high-productivity reservoirs. In the end of the reef and bank deposition of the Lianglitage formation in Tazhong No.1 zone, intensive exposed karstification with large caverns was formed due to the uplift of the eastern structure, the reservoir quality in the eastern area is better than that in the western one. The faulted belts are the main locations where large fractures and caverns with anomaly "beaded" seismic response developed. The fracture-cavern bodies formed by dissolution in multistage burials are mainly controlled by the faults. So, the fractures have constructive effects on post dissolution and reservoir permeability, also, it is significant factor for high oil-gas production. The structural differentiation in Tazhong No.1 zone allows the distribution of reef and bank body and the development of reservoirs to be of subsection property. The eastern platform margin is in high, steep, long and narrow location, in which the fracture-cavern reservoirs well developed due to weathering crust karstification and structural action, being favorable for high and stable petroleum production. The western area with underdeveloped faults has broad but ramp platform margin dominated by low porous reservoirs.