大港探区上古生界沉积特征与控制因素

Sedimentary Characteristics and Control Factors of Upper Palaeozoic in Dagang Exploration Area

大港探区上古生界近期取得一系列勘探突破,展现出良好的勘探前景,已成为重要的储量接替领域.但其勘探程度较低,对于沉积相类型与沉积演化认识上的欠缺制约着该层系勘探的深入和井位的部署.以沉积学理论为指导,在岩心、薄片、测井和录井等资料研究的基础上,明确了区内上古生界各组发育的沉积相类型与沉积演化过程,分析了沉积相发育的控制因素.研究表明,区内本溪组发育障壁海岸相和碳酸盐台地相,太原组发育障壁海岸相、碳酸盐台地相和湿地相,山西组发育浅水三角洲相,下石盒子组和上石盒子组发育河流相.本溪组至上石盒子组的沉积相类型反映了晚古生代海侵作用的肇始、发展、衰退的过程.构造作用、海平面变化和古气候共同控制着沉积相类型的发育.

Dagang exploration area has become an important replacement reservoir field thanks to recent break throughs in its Upper Paleozoic showing good exploration prospects.However,its exploration degree stays low because further exploration of series of strata and well deployment is restricted due to our lack of understanding of the types of sedimentary facies and sedimentary evolution.Based on sedimentology theories,study of cores,slices,well log and logging,types of sedimentary facies and evolution process of every formation in Dagang exploration area of Upper Paleozoic are determined,and the controlling factors of sedimentary facies development are analyzed in this paper.Results show that Benxi Formation in Dagang are adevelops barrier coast facies and carbonate platform facies,Taiyuan Formation develops barrier coast facies,carbonate platform facies and wet land facies,Shanxi Formation develops shallow delta facies,and lower Shihezi and upper Shihezi Formation develops fluvial facies.The type of sedimentary facies from Benxi formation to the upper Shihezi Formation reflects the start,development and decline process of transgression in late Paleozoic.Tectonism,sea level changing and paleoclimate all control the development of sedimentary facies types.