鄂尔多斯盆地姬塬地区长9段砂体构型

为明确鄂尔多斯盆地姬塬地区长9段双物源沉积砂体空间组合形态,利用岩心、测井、测试及生产资料,在确定姬塬地区长9段沉积特征基础上,通过逐级解剖砂体构型,分析双物源背景下的砂体发育规律,表征构型要素类型和特征及其组合分布形态。姬塬地区长9段存在8种骨架构型要素,不同沉积区域的构型要素种类不同,西部主要构型要素为辫状河道、废弃河道和越岸沉积,以水下分流河道和分流间湾沉积为主;东部主要为河口坝、前缘席状砂和水下天然堤。平面上,辫状河道构型要素延伸距离较长,分布较连续;废弃河道构型要素延伸距离短,分布断续;水下分流河道构型要素延伸较远,但分布不稳定;河口坝构型要素通常在水下分流河道的侧后方,连续性较差。纵向上,骨架砂体构型要素的叠置和组合程度自下而上逐渐变差,西部辫状河三角洲体系的构型要素发育规模和程度均优于东部曲流河三角洲体系。

Sand Body Architecture of Chang 9 Member in Jiyuan Area,Ordos Basin

In order to clarify the spatial configuration of sand bodies under the dual-provenance background in Chang 9 member in Jiyuan area,Ordos basin,the sedimentary characteristics of Chang 9 member were determined by using the core,logging,test and production data. On this basis,the sand body architecture of Chang 9 member was dissected level by level to understand the development of sand bodies under the dual-provenance background and to characterize the architectural elements and their assemblage and distribution. The results reveal that there are 8 types of skeleton architectural elements in Chang 9 member,which are different from region to region: braided channel,abandoned channel and cross-bank deposits dominated by underwater distributary channel and interdistributary bay in the west; and estuary sand bar,front sheet sand and underwater natural levee in the east. On the plane,the architectural element of braided channel extends farther with continuous distribution,the architectural element of abandoned channel extends shortly with intermittent distribution,the architectural element of underwater distributary channel extends farther with discontinuous distribution,and the architectural element of estuary sand bar is usually in the side rear of the underwater distributary channel with poor continuity. Vertically,the superimposition and assemblage of the architectural elements of skeleton sand bodies become worse from bottom to top,and the architectural elements of braided river delta system in the west display better development scale and degree than those of meandering river delta system in the east.