准南八道湾组扇三角洲岩相特征及分流河道砂体对比的约束条件

准噶尔盆地南缘八道湾组露头主要发育9种岩相,4种典型的岩相组合,为典型的扇三角洲沉积,扇三角洲平原分流河道是主要储集砂体类型.露头剖面精细解释表明,基准面上升与下降半旋回转换面附近,单砂体孤立状分布.随着基准面不断下降,砂体呈多边-多层式叠置.剖面实测结果显示八道湾组扇三角洲平原分流河道的宽厚比为15～22.不同资料约束下的单砂体室内对比结果表明:约束条件较少时,厚层砂体的对比结果也相对准确,薄层砂体的对比准确性随室内研究人员掌握资料程度增加而提高.基准面旋回约束砂体的垂向叠置形式,宽厚比控制单砂体的侧向延伸距离.

Lithofacies characteristics of fan delta and constraint conditions for sandbody correlation of distributary channels of Badaowan Formation in the south margin of Junggar Basin

Nine lithofacies and four typical lithofacies associations are found in the outcrops of Badaowan Formation in the south margin of Junggar Basin.According to the characteristics of the lithofacies associations,Badaowan Formation is confirmed as typical fan delta deposit.Distributary channels in fan delta plain are the major reservoir sandbodies.Based on fine interpretation of outcrop profiles,single sandbody distributes in isolation near the transition surface between base-level rising semi-cycle and base-level descending semi-cycle.With the continuously descending of base-level,sandbodies present multilateral-multilayer superposition.The width-to-thickness ratio of distributary channel in fan delta plain of Badaowan Formation is 15~22.According to the indoor single sandbody correlation results constrained by different data,the correlation results of thick sandbodies are relatively accurate even when constraining conditions are less.The correlation accuracy of thin sandbodies will increase with the increase of data provided to indoor researchers.Base-level cycle mainly controls the vertical superposition pattern of sandbodies,while quantitative geological knowledge database(width-to-thickness ratio) mainly controls the lateral extending distance of single sandbody.