鄂尔多斯盆地大牛地气田山西组砂体组合类型及成因模式

根据岩心资料、录井资料及测井资料，对鄂尔多斯盆地大牛地气田二叠系山西组的砂体组合类型及成因进行了仔细研究，认为山西组砂体成因类型包括水下分流河道砂体、河口坝砂体、远砂坝砂体和席状砂砂体;山西组为一套辫状河三角洲前缘沉积砂体组合，发育4种砂体组合类型，分别是叠覆冲刷水下分流河道砂体组合、叠置河口砂坝砂体组合、水下分流河道-河口砂坝砂体组合、远砂坝-席状砂砂体组合。同时认为，沉积物的供给方式、供给量及可容纳空间升降是控制大牛地气田山西组沉积时期不同成因砂体组合时空分布规律的主要因素。基于以上研究认识，建立了研究区进积式———可容纳空间降低模式和退积式———可容纳空间上升模式两种砂体成因模式。结合油田实际情况，综合分析认为水下分流河道及分流河口砂坝砂体仍为山西组下一步勘探最具潜力的目标。

Assemblage types and genetic models of the Shanxi sandbodies in Daniudi gasfield,the Ordos Basin

According to core and logging data，this paper examines the origins and assemblage types of sandbodies in the Permian Shanxi Formation in Daniudi gasfield，the Ordos Basin.We believe that the genetic types of sand-bodies in the Shanxi Formation include underwater distributary channel sands，mouth bar sands，distal bar sands and sheet-like sands.The Shanxi Formation consists of4types of braided river delta front sandbody assemblages，including superimposed and scoured underwater distributary channel sands，overlappedmouth bars，underwater distributary water-mouth bar sands and distal bar sands sheet-like sands.Ways and volume of sediment input and change of accommodation are the key factors that control the temperal and spatial distribution patterns of sandbody assemblages of different genetic types during the deposition of the ShanxiFormation in Daniudi gasfield.Based on these results，we set up two geneticmodelss of sandbodies for the study area，one being prograding accommodation decreasingmodel and the other being retrograding accommodation enlargingmodel.It is proposed thatunderwater distributary channel sands and distributarymouth bar sands are the potential exploration targets in the ShanxiFormation.