准噶尔盆地中部2、4区块侏罗系头屯河组物源体系及沉积演化特征

The Provenance Systems and Characteristics of Sedimentary Evolution of Jurassic Toutunhe Formation in the 2^(nd) and 4^(th) Blocks of Central Junggar Basin

目前准噶尔盆地中部(以下简称"准中")2、4区块勘探程度较低,根据钻井、地震及野外踏勘等资料,利用古地貌分析确定物源方向,单井相、地震相分析确定相类型,连井相分析明确相变化,地震切片约束相边界等,实现点、线、面结合,对准中2、4区块侏罗系头屯河组(J2t)沉积体系展开综合研究。结果表明,研究区J2t主要发育曲流河-三角洲-湖泊沉积体系,物源主要受北东向克拉美丽山控制。头屯河组一段、二段(J2t1、J2t2)沉积时期,东部主要发育三角洲沉积,西部主要发育滨浅湖滩坝沉积;头屯河组三段(J2t3)沉积时期,全区普遍发育曲流河背景下的冲积平原沉积。并认识到J2t沉积时期,气候逐渐干旱,物源供应不足,湖盆快速萎缩,冲积平原逐渐扩大的演化过程。最终明确了滩坝砂和河道砂为主要砂体类型,以此为指导,对砂体进行了有效描述。

The exploration level in 2nd and 4th blocks of Central Junggar Basin(hereafter referred to as 'Zhunzhong')was low.According to the drilling,seismic and field survey and other data,palaeogeomorphologic analysis was used to determine source direction and single well facies and seismic analyses were used to determine the facies type;well connection analysis was used to determine the facies changes;seismic slice was used to constrain facies boundary.By using the methods mentioned above,apoint-line-surface combination would be realized,a comprehensive study was performed on sedimentary system in Toutunhe Formation(J2t)in the2 nd and 4th blocks of Central Junggar Basin.The results illustrate that a meandering river-delta-lake sedimentary system is mainly developed in J2 t,provenance is controlled by Kelameili Mountain which is in the northeast.Moreover,delta deposition is developed in the east of study area,loch beach barrier deposition is developed in the west of study area in J2t1 and J2t2sedimentary periods.Alluvial plain deposition is generally developed in the whole study area at the background of meandering stream in J2t3 sedimentary period.In addition,it is considered in J2 t sedimentary period that the climate is arid,source is insufficient,the lake shrinks rapidly and alluvial plain gradually expanded.Eventually it is determined that the main types of sand body are beach bar sand and channel sand,and it is used as a guidance to describe sand body.