准噶尔盆地东部地区八道湾组沉积相与油气富集

SEDIMENTARY FACIES AND HYDROCARBON ACCUMULATION OF THE JURASSIC BADAOWAN FORMATION IN DISHUIQUAN,EASTERN JUNGGAR BASIN

准噶尔盆地东部滴水泉油田侏罗系八道湾组依据岩性在纵向上表现为"粗—细—粗"的变化,将其自下而上划分为三段,识别出辫状河、辫状河三角洲、湖泊3种沉积相以及5种沉积亚相,主要发育2套大的储盖组合,辫状河道砂体和辫状河三角洲分流河道砂体是最有利的储集砂体,主要发育于J1b1段和J1b3段中下部,区域性的泥岩盖层主要发育于J1b2段和J1b3段上部。不整合面、断裂和骨架砂体构成输导体系。目前已发现的油气主要富集在J1b1段辫状河道亚相中,且位于克拉美丽山前古斜坡带与古沟谷相交处。造成这种油气聚集差异主要包括不整合面和沟谷型古地貌两方面原因,识别出7个古沟谷,沟谷型古地貌可与J1b1段广泛分布的辫状河道砂体组合形成地层—岩性油气藏,是研究区最有利的勘探目标。

The Jurassic Badaowan Formation in the Dishuiquan area,eastern Junggar Basin,can divided into three members,J1b^1,J1b^2 and J1b^3.representing a fining-upward followed by a coarsening-upward sequence.There are mainly three sedimentary facies（braided river,braided river delta,and lacustrine facies）,five sedimentary subfacies,and two large reservoir-seal assemblages.Braided channel sand bodies and distributary channel sand bodies,which mainly developed in J1b^1 and the lower to middle part of J1b^3,are favorable reservoirs.Regional mudstone seals mainly developed in J1b^2 and the upper part of J1b^3.Unconformity surfaces,fractures and skeleton sand bodies constitute the hydrocarbon transport system.Oil and gas were mainly assembled in the braided channel sand bodies which are located in the junction of ancient slope belt of Kelameili and ancient valleys in J1b^1.Factors that control hydrocarbon accumulation include unconformity surfaces and ancient valleys.Seven ancient valleys have been identified,and they could form stratigraphic-lithologic reservoirs in braided river channel sand bodies that are widely distributed in J1b^1 and are the most advantageous exploration targets in the study area.