塔北地区奥陶系碳酸盐岩颗粒滩沉积特征及分布规律

摘要

为了深入研究塔北地区奥陶系碳酸盐岩颗粒滩沉积特征与分布规律.利用地震、测井、岩心和薄片等资料,分析了塔北地区奥陶系一间房组和良里塔格组的岩石学特征,颗粒滩体的沉积特征、垂向组合和分布规律等,并探讨了颗粒滩发育的主控因素与良里塔格组颗粒滩发育储层的可能性.结果表明:塔北地区一间房组为浅水宽缓台地,垂向上发育厚层颗粒滩和生物礁,颗粒滩体呈连片状分布,点礁分散于缓坡高能带,沉积微相主要为内碎屑滩、藻粒滩、生屑滩和鲕粒滩等;良里塔格组为弱镶边型台地,垂向上发育中厚层颗粒滩和生物礁丘,颗粒滩体呈片状分布于台缘洼地中,环绕古隆起呈环带状展布,沉积微相主要为内碎屑滩、藻粒滩、生屑滩、鲕粒滩和核形石滩等.颗粒滩体的发育主要受海平面相对变化、水体能量和古地貌影响,良里塔格组颗粒滩的发育规模虽不如一间房组,但其台缘带的颗粒滩仍可发育良好储层,为塔北地区潜在的油气储层段.%The data of seismic,logging,core and thin sections were used to analyze the petrology characteristics, sedimentary characteristics,vertical depositional combination and distribution regularities of Ordovician Yijian-fang Formation and Lianglitage Formation in northern Tarim Basin,and the main controlling factors of carbon-ate shoals development and the possibility about effective reservoir development of Lianglitage Formation were discussed. The results show that the sedimentary microfacies of Yijianfang Formation can be divided into four types:intraclastic shoal,algaeclastic shoal,bioclastic shoal and oolitic shoal. Tabei area was shallow and width platform during the Yijianfang Formation depositional stage,thick-layer grainstone shoal and reefs were developed vertically. The platform grainstone shoals present plate-like with good lateral continuity,and the reefs scattered among high-energy zones. The sedimentary microfacies of Lianglitage Formation can be divided into five types:intraclastic shoal,algae clastic shoal,bioclastic shoal,oolitic shoal and oncolite shoal. Tabei area turned into weak rimmed platform during the Lianglitage Formation depositional stage. The water was deep and less high-enegry facies developed. Medium-thick layer grainstone shoals and reefs were developed vertically. The grainstone shoals distributed as plate-like among the depression,and around the paleo-uplift as circle-type distribution. The development of grainstone shoals was mainly affected by relative sea level change,hydrodynamic conditions and paleogeomorphology. The development scale of grainstone shoal during Lianglitage Formation depositional stage is less than that of Yijianfang Formation depositional stage,however,the grainstone shoals in platform margin still could develop into effective reservoir,which is potential oil-gas reservoir.