塔河油田奥陶系碳酸盐岩沉积相及地层学研究

根据岩心和薄片观察,塔河南缘S69—S76井的亮晶鲕粒灰岩和藻粘结灰岩与其它地区的微晶灰岩、亮晶砾砂屑灰岩及微亮晶砂屑灰岩形成对比,因而早奥陶世的沉积格局分界线应西移到库南2井—满参1井一线。依据岩性、岩石结构、沉积构造、剖面结构、古生物组合等标志,识别出下奥陶统有开阔台地相、台内浅滩相和台地边缘丘滩相3种沉积相类型;中上奥陶统为较深水陆棚相和潮缘沉积相。从层序地层学的角度将下奥陶统划分为海侵体系域和高水位体系域两个二级层序;中上奥陶统划分为海侵体系域、高水位体系域和低水位体系域。同时研究了层序和体系域的发育特征,初步确定了下奥陶统层序地层的对比方案。

STUDY ON THE SEDIMENTARY FACIES AND SEQUENCE STRATIGRAPHY OF THE ORDOVICIAN CARBONATE ROCK IN TAHE OILFIELD

In accordance with core and thin section observation,the oosparite and algal bindstone of S69-S76 wells on the southern margin of Tahe oilfield is in contrast with the micrite,sparry limerudite or limearenite and microspar limearenite in the other areas.So,the boundary of the Early Ordovician sedimentary framework should be shifted westward to the line along Kunan 2 to Mancan 1 wells.According to lithology,rock texture,sedimentary tectonics,section structire,paleontological assemblages and other marks,open platform,intraplatform shoal and platform-marginal knob-and-beach three types of sedimentary facies were recognized in the Lower Ordovician,and deeper-water shelf and peritidal sedimentary facies were recognized in the Middle-Upper Ordovician.From the angle of sequence stratigraphy,the Lower Ordovician can be divided into transgressive and high-water level system domains two secondary sequences,and the Middle-Upper Ordovician can be divided into transgressive,high-water level and low-water level system domains.Meantime,the development characteristics of sequences and system domains were studied,and the comparison scheme of the Lower Ordovician sequence stratigraphy was determined preliminarily.