鄂尔多斯盆地姬塬地区长8_1浅水三角洲砂体成因  

The Genesis of Sandbody in the Shallow Delta from Chang 8_1 of Jiyuan Area in Ordos Baisn

作　　者：李树同[1] 王琪[1] 仲佳爱[1,2] 邱军利[1] 刘志伟[3] 乔华伟[4] 廖朋[1,2] 

机构地区：[1]中国科学院油气资源研究重点实验室,甘肃兰州730000 [2]中国科学院院大学,北京100049 [3]长庆油田分公司工程技术管理部,陕西西安710021 [4]中国石油长庆油田分公司第三采油厂,宁夏银川750006

出　　处：《天然气地球科学》2013年第6期1102-1108,共7页Natural Gas Geoscience

基　　金：“中国科学院西部之光”项目;中国科学院油气资源研究重点实验室开放基金项目(编号:KFJJ2010-01)联合资助

摘　　要：鄂尔多斯盆地长8段为浅水三角洲沉积,其沉积特征与典型的Gilbert三角洲有所不同。主要利用测井、岩心和薄片等资料,重点分析了姬塬地区长81砂体的物源搬运距离、物源补给量大小以及湖水水体性质、水动力条件等,确定了姬塬地区长81砂体沉积环境和形成条件。分析认为姬塬地区长81砂体距离物源区较近,物源供给稳定且较为充足;研究区长81期湖水水体浅且为微咸水,湖盆底部形态平缓,属于浅水三角洲沉积环境,其中,在长81期基准面上升过程中,湖水强势扩张使得湖水扩张动力大于河流入湖动力。姬塬地区长81沉积期,在物源补给量稳定且较为充足、湖水扩张动力强于河流入湖水动力的条件下,砂体受到湖水强烈的顶托作用,使砂体被动提前卸载,于是形成了垂向叠加期次不明显、纵向延伸距离长且连续性好的"连续退积式"厚层砂体。Chang 8member in the Ordos Basin belongs to shallow-water delta sedimentation,which is different from typical Gilbert delta deposit.Using data of logging,drill core and thin sections,this paper analyzes the transportation distance and the supply of provenances,the properties of the lake water and hydrodynamic condition of Chang 81sandbody in Jiyuan area,so as to determine its sedimentary environment and formation condition.The analysis suggests that the sandbody of Chang 81in Jiyuan area is close to the provenance and the provenances are enough and has stable supply ability.In the study area,Chang 81belongs to shallow-water delta deposits which are characterized by shallow and brackish water and gentle topography of the bottom of the lake basin.During the ascending period of base level of Chang 81the aggressive expansion of the water made the driving force of the water expansion greater than that of the river flowing into the lake.On the condition of enough and stable provenance supply and the driving force of the water expansion greater than that of the river flowing into the lake,the sandbody passivity unload ahead of time due to lake water strong top support action,thereby creating a continuous retrogradation sandbody with unobvious superposition stages in vertical but long extended distance and good continuity in horizontal.

关 键 词：物源补给量 沉积环境 成因模式 延长组 鄂尔多斯盆地 

分 类 号：TE122.21[石油与天然气工程—油气勘探]