塔中古城墟隆起奥陶系钻探成果与勘探意义

The Drilling Efforts and Significance of Ordovician in Guchengxu Uplift of Tazhong Area

位于塔里木盆地中央隆起带东段的古城墟隆起,奥陶系齐全,新发现中奥陶统一间房组-下奥陶统鹰山组颗粒灰岩孔隙型储集层。该类储集层主要储集空间为粒间孔、晶间孔和针尖状溶蚀孔,在微裂缝、缝合线等连通下形成了厚度约2～50m、分布较广泛的似层状孔隙型储集体。成像测井资料的进一步解释处理发现,其孔隙度达4%.该类储集层主要受台地边缘砂屑滩相展布的控制,后期溶蚀作用有利于改善其储集性能。颗粒灰岩储集体与上覆上奥陶统泥质岩区域性盖层组成良好的储盖组合,并具有良好的封闭性,在烃源区高成熟油气多期充注下形成了多层潜在油气藏。在已完钻的1口探井中经中途测试获气流,充分展现了这一勘探领域的巨大潜力。

Guchengxu uplift locaed in the east side of central uplift in Tarim basin indicates that the Ordovician strat are complete,and the grain limestone and porous-type reservois in Yijianfang formation of Middle Ordovician-Yingsan formation of Lower Ordovicain are newly discovered in this area,The reservoirs rocks are characterized by intergranular pores,intercrystal pores and pinpoint-like solution pores,with micro-fissures and sutures as channels,shaping 2-50 m thick and wide spreading layered porous-type reservooirs with 4percent of porosity given by the inter pretation of imageing logging data,The study shows that such reservoris were mainly controlled by distrbution of tableland marginal sand-bank facies,and post-solution was advantageous to improvement of their storage performances,the good ressrvoir-cap rock assemblage was formed by the grain limestone reervoirs and overlying shale of Upper Ordovician as the regional cap rocks;the good sealing nature allowed to shape multilayer and potential reservoirs under multistage fillings of highly matured hydrocarbons in the source area,Gas flow fro, a well drilled and completed in this area by drillstem test has fully revealed its tremendous potentials for petroleum exploration here.