Abstract: It is obvious that there are no Upper Permian and Lower Triassic in the Toksum Depression and Keyayi Depression in the western Turpan-Hami Basin,and has an angular discordance between Middle Carboniferous,Lower Permian and Middle Triassic.In the period of Carboniferous and Early Permian, vocanic activity was strong with high geotemperature.During Middle Triassic,a extend lake appeared in Toksum and Keyayi areas.The hydrocarbon generating center was in Keyayi area in which the good source rocks were developed.The fan delta reserviors were developed in littoral-shallow lake in Toksum Depression,the oil derived from Middle Triassic is mainly come from Keyayi area.In the later Triassic,the depocenter had been migrated to middle and southern Toksum Depression where littoral-shallow lake facies were developed.The Indosinian movement and early Yanshanian movement are tectonic thermal events which play an important role in the maturity of source rock.The northern-western Toksum Depression has fairly good oil exploring prospect because it is near hydrocarbon generating center,and physical property of fan delta sandbodies has been improved in lately tectonic movements,and the period of hydrocarbon generating is close to that trap structures forming as well as it is situated in the place where fractures developed.Pre-Jurassic in Keyayi Depression has perfect formative conditions of oil-accumulation,but has poor conservative conditions.

Key words: Toksum Depression, Keyayi Depression, oil-gas exploring prospect, Turpan-Hami Basin

摘要： 吐-哈盆地西部的托克逊凹陷和科牙依凹陷缺失上二叠统和下三叠统,中石炭统、下二叠统与中三叠统呈角度不整合接触.石炭纪和早二叠世时地温高,火山活动强烈.中三叠世时托克逊地区与科牙依地区为同一湖盆,科牙依地区为生烃中心,发育优质烃源岩;托克逊地区为滨浅湖,发育扇三角洲储层,该区中三叠统的油主要来自科牙依地区.晚三叠世时沉积中心移至托克逊地区中南部,发育滨浅湖沉积.中晚三叠世的印支运动和中侏罗世的早燕山运动为构造热事件,对三叠系烃源岩成熟起到重要作用.托克逊地区西北部因邻近生烃中心、扇三角洲砂体在后期构造运动中物性得到改善,生烃期与圈闭形成期匹配以及位于断裂发育有利部位而具有一定的勘探前景.科牙依凹陷前侏罗系具良好的油藏形成条件,但保存条件较差.

关键词: 托克逊凹陷, 科牙依凹陷, 油气勘探前景, 前侏罗系, 吐-哈盆地