鄂尔多斯盆地北部盒8段砂体形成机理分析

Formation mechanism of sand bodies of the eighth member of Shihezi Formation in northern Ordos Basin

为了明确鄂尔多斯盆地北部二叠系盒8段大面积砂体的形成机理,在分析砂体展布特征的基础上,全面恢复了盒8期湖盆底形、湖泊与外界的连通性、物源供给及水动力条件等沉积古环境要素,并结合水槽沉积模拟实验,建立了盒8段沉积模式。研究认为:充足的物源供给、较强的水动力、多水系输砂、平缓的湖盆底形、盆地快速稳定的沉降和湖岸线大范围反复波动,是盒8段大面积砂体形成的必要条件;鄂尔多斯盆地鄂托克前旗―榆林以南、L63井—S318井—Y101井—Y112井以北区域,是下一步的有利勘探目标。

In order to clarify the formation mechanism of sand bodies in the eighth member of Permian Shihezi Formation in the northern Ordos Basin, the sedimentary palaeoenvironments including basin character, the connectivity of lake and the outside world, provenance supply and hydrodynamic force conditions were recovered on the base of the characteristics of sand body distribution. Combined with the sedimentary simulation, the sedimentary model of the eighth member of Shihezi Formation was established. The result shows that sufficient sediment supply, strong hydrodynamic force, abundant clastic supplying by several rivers, broad flat topography, stable and rapid basin subsidence and lake level fluctuate with large range are the main factors responsible for the large-area sand bodies of the eighth member of Shihezi Formation. The area from the north of L63 well, S318 well, Y101 well and Y112 well to south of Etuokeqianqi-Yulin area in Ordos Basin is the favorable target for exploration in the future.