准噶尔盆地南缘下组合成藏条件与大油气田勘探前景

Conditions for gas pooling in the lower assemblage in the southern margin of the Junggar Basin and the exploration prospect of large hydrocarbon fields

准噶尔盆地是一个油气资源丰富的叠合含油气盆地,该盆地南缘下部成藏组合贴近准南主要烃源层———中下侏罗统煤系地层,宽缓大中型构造圈闭多,上侏罗统—下白垩统深部规模有效储集层发育,下白垩统吐谷鲁群厚层湖相泥岩及三叠系、中下侏罗统各层组内部湖湘泥岩盖层条件好。研究结果表明:该区圈闭与规模有效储集层空间发育匹配;圈闭形成时间与主生排烃期时间匹配;白垩系吐谷鲁群区域盖层与中上侏罗统储盖组合匹配,油气资源量大、发现程度低。结论认为:该区具备大油气田成藏条件,具有良好的勘探前景。

The Junggar Basin is a superimposed hydrocarbon basin with rich oil and gas resources in the southern marginal area of which there are Middle and Lower Jurassic coal strata as the major source beds in the lower assemblage.Additionally,there are many large and middle structural traps;effective reservoirs are well developed in the deep Upper Jurassic and Lower Cretaceous areas;and good cap rocks are provided by lacustrine mudstone with great thickness in the Middle and Lower Jurassic,the Tertiary and the Lower Cretaceous formations of the Tugulu Groups.It is concluded that the traps match well with the effective reservoirs;the formation time of traps coincides with the time of hydrocarbon generation and charging;the regional cap rocks in the Cretaceous formation of the Tugulu Grousp correspond with the assemblage of the Middle and Lower Jurassic formations.All these above prove that this study area with abundant hydrocarbon resources and low exploration maturity has apparently good pooling conditions for large oil or gas fields,which means a good prospect for hydrocarbon exploration.