摘要
在研究野外露头、钻井岩心、测井资料的基础上,对鄂尔多斯盆地东北部山西组主要沉积相类型——三角洲相的沉积演化特征进行了研究。识别出东部和西部两大三角洲体系,其三角洲平原包括分流河道、天然堤、决口扇、平原沼泽和洪泛平原等微相,三角洲前缘包括水下分流河道、河口坝、潮汐砂坝、远砂坝、分流间湾等微相。三角洲平原的分流河道早期具有辫状河性质,晚期向曲流河转变。三角洲类型在山23、山22期为发育在潮坪背景上的河流-潮控三角洲,以后转变为发育在陆相湖泊环境中的河控-湖泊三角洲。不同三角洲类型和相应的亚相、微相特征控制了本区岩相变化特征、砂体展布特征和砂体的储集性能。其中以山23亚段三角洲前缘的水下分流河道、潮汐砂坝、河口坝和三角洲平原的分流河道在岩性、砂体厚度以及砂体储集性能方面更具优越性,从而成为勘探开发的重点。
On the basis of the research on field outcrops, well cores and well logging data, this paper discusses the sedimentary and evolution characters of the main sedimentary facies （delta facies） of the Lower Permian Shanxi Formation in the northeast of Ordos Basin. It identifies two delta systems lying in the east part and west part of the research area, respectively. The delta plain can be divided into distributary channel, natural levee, splay, plain swamp and flood plain microfacies. The delta front includes underwater distributary channel, estuary bar, tide sandbar, distal sandbar, inter-distributary bay microfacies. The distributary channels were braided channels in P1s^2（Member 2 of the Shanxi Formation） stage, and they changed into meander channels afterward. In P1s^2-3 and P1s^2-2 （Member 2-3 and Member 2-2 of the Shanxi Formation） stages, river-tide controlled delta developed in the background of tide flat, and river controlled lake delta grew with sea water withdrawing from the southeast and lake environment emerging. Different types of facies, sub-facies and microfacies will control the lithofacies change character, sandbody distribution character and reservoir performance of the sandbody. Because the underwater distributary channels, tide sandbars and estuary bars in the delta front and the distributary channels in the delta plain of P1s^2-3 sub-segment have more excellent quality in lithofacies, sandbody thickness and reservoir performance of the sandbody, they are key targets of exploration and exploitation.
出处
《成都理工大学学报（自然科学版）》
CAS
CSCD
北大核心
2008年第6期693-699,共7页
Journal of Chengdu University of Technology: Science & Technology Edition
