准噶尔盆地红车地区三叠系层序地层特征

Sequence stratigraphy of Triassic in Hongche area, Junggar Basin

以层序地层学和沉积学的基本理论为指导,在大量测井、钻井、地震、分析化验等资料综合分析的基础上,对红车地区三叠系进行层序地层划分对比,将整个三叠系划分为5个三级层序（TSQ1—TSQ5）,其中TSQ2相当于克拉玛依下亚组,TSQ3相当于克拉玛依上亚组。研究发现,三叠纪进入板内前陆盆地演化阶段,构造活动较缓,无明显的构造坡折,难以识别出初次湖泛面,易识别出最大湖泛面,其下为湖侵体系域,之上为高位体系域。根据准噶尔盆地西北缘构造发育背景和沉积体系的类型及展布,并结合沉积相旋回的演化特征,建立了区内三叠系层序地层发育模式,盆地构造活动等因素对层序的形成具有明显的控制作用。探讨了层序地层格架对油气分布的控制作用,指出TSQ2沉积时期,泛滥平原发育使得其泥质含量较高,更有利于岩性油气藏的形成,尤其在红9井—红61井一带,砂地比普遍在25%~40%,同时该区域储层物性较好,为TSQ2时期岩性圈闭最为有利区域。

By analyzing plentiful geological and geophysical data and based on the fundamental principles of sequence stratigraphy and sedimentology, the isochronal framework of sequence stratigraphy and sedimentary system model of Triassic in Hong-Che area of Junggar Basin have been established. The whole Triassic is divided into five third sequences （TSQ1-TSQ5）, among which TSQ2 is lower Karamay formation and TSQ3 is up Karamay formation. It is found that Triassic plate is in the evolution of the foreland basin stagel and has moderate tectonic activity. It＇s different to identify Ffs but easy to identify Mfs in sequence, transgressive systems tract and highstand systems tract. According to the tectonic development of the background and type of depositional system of northwestern margin of Junggar Basin, and combined with the evolution characters of sedimentary facies, a developing mode of Triassic in the study area is established. Through sequence control factor, basin tectonic activity, climate and lake level fluctuation are found, which~ have apparent control action in sequence. At last, the paper discusses the relationship of the sequence stratigraphy and lithologic trap, and points out that in TSQ2 period, as flood plain developed, it had high shale content, thus favored buildup of lithologic hydrocarbon reservoir. In the plane, the area of Hong9 we11-Hong72 well-Hong61 well is the favorable area because of the low sand ratio （25%- 40%） and the good reservoir quality.