塔河油田西南部地区下奥陶统蓬莱坝组沉积相研究

Sedimentary facies study of the Lower Ordovician Penglaiba Formation in the southwest area of Tahe Oilfield

塔河油田奥陶系是塔河油田近几年油气勘探的重要领域,但是其沉积相类型及展布特征的研究仍旧比较薄弱,制约了下一步的勘探进程。结合沉积相识别标志,对研究区沉积相及其展布特征进行分析。结果显示:研究区下奥陶统蓬莱坝组为局限台地相沉积,发育潮坪、台内滩、潟湖三种亚相,可细分为云坪、灰云坪、灰质湖、云灰湖、砂屑滩5个微相;研究区整体以潮坪沉积为主,蓬莱坝组上段发育潟湖沉积,台内滩发育规模小,孤立分布,纵向上分布于蓬莱坝组上段,平面上自西向东数量逐渐增加。

The Ordovician in the Tahe Oilfield is an important area for oil and gas exploration in recent years,but research on sedimentary facies types and distribution characteristics remains relatively weak,constraining further exploration efforts.Building upon previous understanding,this study combines sedimentary facies identification criteria to analyze sedimentary facies and their distribution characteristics in the study area.The results show that the Lower Ordovician Penglaihe Formation in the study area is characterized by restricted platform sedimentation,with three subfacies including tidal flats,inner-platform shoals,and lagoons,which can be further subdivided into five microfacies:cloudy tidal flat,gray cloudy tidal flat,gray argillaceous lagoon,cloudy-gray lagoon,and sandy shoal.Tidal flat sedimentation predominates in the overall study area,with lagoon sedimentation occurring in the upper part of the Penglaihe Formation.Inner-platform shoals are small in scale and isolated in distribution,longitudinally distributed in the upper part of the Penglaihe Formation,and gradually increasing in quantity from west to east in the planar direction.