博湖坳陷八道湾组露头、单井层序及沉积学研究

Study on crop, single well sequence and sedimentology of Badaowan formation in Bohu depression

主要利用野外露头和钻井(测井)资料,配合使用地震资料的基础上,对焉耆盆地博湖坳陷下侏罗统八道湾组进行了沉积学研究。在建立的焉耆盆地博湖坳陷下侏罗统八道湾组三个三级层序格架的基础上,指出了沉积体系构成上以三角洲-湖湾沼泽相的浅水沉积为主,湖泊水体深度不大且分布范围有限。在研究区识别出的物源体系如下:第一个物源分散体系发育在研究区西南部的巴州煤矿到四十里城地区、北东方向的辫状河三角洲复合体从西南向东北携带沉积物进入研究区中西部发育的"湖湾",且堆积成三角洲朵体;第二个物源分散体系发育在北部凹陷的宝北地区,辫状河三角洲复合体由西北向东南延伸,以湖泊三角洲进入"湖湾"堆积成中小型的辫状河三角洲;第三个物源分散体系发育在本布图地区,辫状河三角洲复合体由西北向东南延伸,进入"湖湾"并堆积成小型的浅水湖泊三角洲;第四个物源在南部凹陷东部,由南向北进积,以发育扇三角洲为主;第五个物源在场浅1井以东,由东向西进积,规模有限。

Based on seismic data, field crop and drilling & logging data, the paper makes a sedimentology study on Bad-aowan formation of lower Jurassic of Bohu depression in Yanqi basin. After establishing three third - order sequence stratigraphic frameworks, the paper points out the sedimentary system composition was mainly shallow system based on delta- lacustrine swamp facies, with shallow water depth and limited distribution range. The identified sedimentary sources in the working area are as the follows; the first disperse source was developed from Ba-zhou coal mine to Sishilicheng area in the southwest. The braided river delta compounds from northeast carries the sediments enter into 'lacustrine' which was developed in the middle- west, and accumulated as delta lobe. The second disperse source was developed in Baobei area of the northern depression, and the braided river delta compounds extended from northwest to southeast. The lake delta entered 'lacustrine' and accumulated as small- middle type braided river delta. The third disperse source was developed in Benbutu area, and the braded river delta compounds also extended from northwest to southeast. When entering 'lacustrine', it accumulated as small type shallow water lake delta. The fourth disperse source lies in the east of the depression and stretched from south to north, with the fan delta as the main form. The fifth disperse source lies in the east of Changqian 1 well, and stretched from east to west, but with limited scale.