准噶尔盆地红车断裂带多源多期油气成藏控制因素及有利勘探方向

Controlling factors of multi-source and multi-stage complex hydrocarbon accumulation and favorable exploration area in the Hongche fault zone,Junggar Basin

准噶尔盆地红车断裂带紧邻沙湾凹陷,成藏条件极为有利,勘探潜力巨大,但不同阶段油气混杂分布,不同区带成藏控制因素认识不清,制约了该区块下一步油气勘探与开发。通过油源生物标志化合物对比、烃类流体包裹体分析及地震资料等研究,对红车断裂带的油气源、成藏期次、成藏主控因素及有利勘探方向进行了探讨。研究结果表明:红车断裂带原油可以划分为4类,主要来源于风城组和下乌尔禾组烃源岩;天然气可以划分为5类,来源于石炭系、佳木河组、风城组和下乌尔禾组4套烃源岩。红车断裂带油气藏具有“两期原油充注、晚期干气侵入”的成藏特征,第一期为晚三叠世-早侏罗世成藏期,第二期为早-中白垩世成藏期,晚期成藏(干气侵入)发生在晚白垩世之后。红车断裂带油气藏受四大成藏因素控制:多套烃源岩为油气成藏奠定了物质基础;断裂与不整合为油气运移提供了输导条件;断裂封闭性与构造演化差异控制了油气复杂分布;保存条件差导致研究区天然气难以大规模成藏。在此基础上,建立了红车断裂带北段、南段多源多期油气成藏模式。以该研究认识为指导,指出斜坡区和断裂带下盘以及南段深层是研究区下一步有利勘探方向。

The Hongche fault zone is adjacent to the Shawan Sag in the Junggar Basin,with favorable reservoir forming conditions and great exploration potential.However,the mixed distribution of oil and gas in different stages and the unclear understanding of reservoir forming controlling factors in different zones restrict the next oil and gas exploration and development in this block.Based on the comparison of biomarker compounds,fluid inclusion analysis and seismic data,the oil and gas sources,accumulation periods,main controlling factors and favorable exploration targets of Hongche fault zone were discussed.The results show that the crude oil in the Hongche fault zone can be divided into four categories,which are mainly derived from the source rocks of the Fengcheng Formation and the Lower Urho Formation.The natural gas can be divided into five categories,which are derived from four sets of source rocks of Carboniferous,Jiamusi,Fengcheng and Lower Urho formations.The oil and gas reservoirs in the Hongche fault zone have the accumulation characteristics of“two stages of crude oil filling and late dry gas intrusion”.The first stage is the Late Triassic-Early Jurassic accumulation period,the second stage is the Early-Middle Cretaceous accumulation period,and the late dry gas intrusion occurs after the Late Cretaceous.Hongche fault zone is controlled by four hydrocarbon accumulation factors:multiple sets of source rocks establish the material foundation for hydrocarbon accumulation;fault and unconformity surfaces provide a transmission system for large-scale lateral migration of oil and gas;the difference of fault sealing and structural evolution control the differences of oil and gas geochemistry characteristics in different zones;poor preservation conditions make it difficult to form large-scale gas reservoirs in the study area.Based on this,the accumulation model of the northern and southern sections of Hongche fault zone is established.Guided by the study,it is pointed out that the slope area,the footwall of fault zone and the deep layer of southern segment are the next favorable exploration targets.