渤海湾盆地济阳坳陷北部石炭系—二叠系残留地层沉积*

渤海湾盆地济阳坳陷北部石炭系—二叠系残留地层为近年来该地区油气勘探的重点领域。为明确古潜山储集层沉积相带与砂体展布规律,在地层划分对比的基础上,依据测井曲线、沉积构造、岩性特征及沉积序列等资料,对济阳坳陷北部石炭系—二叠系古潜山区沉积特征进行了系统研究。结果发现: (1)古潜山区石炭系—二叠系残留地层厚度变化很大,石千峰组被剥蚀殆尽; (2)石炭纪—二叠纪研究区经历了海陆交互相→海陆过渡相→河流相的演化过程, 其中本溪组及太原组沉积时期研究区发育潟湖、潮坪及障壁岛相,山西组沉积时期发育三角洲相,以三角洲平原亚相为主,可识别出分流河道、分流河道间、天然堤及泥炭沼泽等微相,而上、下石盒子组沉积时期以辫状河沉积为主,可进一步划分为心滩、河床滞留沉积及泛滥平原微相; (3)受沉积环境演化的控制,本溪组—太原组的砂体呈斑块状展布,山西组和上、下石盒子组的砂体呈近北东—南西向条带状展布。对济阳坳陷北部潜山区沉积相与砂体展布规律的研究,为该古潜山区的油气勘探提供了关键地质依据。

Sedimentary facies of the Carboniferous-Permian residual strata in northern Jiyang Depression,Bohai Bay Basin

The Carboniferous-Permian residual strata in the northern Jiyang Depression of the Bohai Bay Basin has become one of the key areas for oil and gas exploration in recent years. In order to clearly understand the distribution characteristics of sedimentary facies and sand body in ancient buried hill reservoir,the sedimentary characteristics of the Carboniferous-Permian in the northern Jiyang Depression of Bohai Bay Basin have been systematically studied based on the stratigraphic division and correlation,well logs,sedimentary structures,lithology and sedimentary sequences. Results show that the thickness of the Carboniferous-Permian strata in the buried hill area has changed rapidly,and the Shiqianfeng Formation have been almost eroded. During the Carboniferous-Permian period,the study area underwent the evolution process of alternating continent-marine facies,continent-marine transitional facies and river facies. During the Benxi and Taiyuan Formations depositional period,the lagoon,tidal flat and barrier island facies developed in the study area. The delta facies developed in the Shanxi Formation depositional period,and it was mainly characterized as the delta plain deposits,which can identify the detailed facies such as distributary channel,interdistributary channel,natural levee and peat swamp. During the Upper and Lower Shihezi Formations,braided river facies was the dominated sedimentary facies and it was divided into channel bar,channel lag deposits and floodplain microfacies. The sand bodies in the Benxi and Taiyuan Formations are spotted distributed under control of the evolution of sedimentary environment. The sand bodies of Shanxi Formation,the Lower and Upper Shihezi Formation are distributed in a banded strip near NE to SW direction. The studies on the sedimentary facies and distribution law of sand bodies in the buried hills of the northern Jiyang Depression can provide key geological basis for oil and gas exploration in the ancient buried hills.