准噶尔盆地乌尔禾—夏子街地区不整合发育特征及其在油气成藏中的作用

准噶尔盆地乌尔禾夏子街地区二叠系至侏罗系发育多期不整合，包括削截及多期削截不整合、超覆不整合、褶曲不整合、断褶不整合和平行不整合。风化剥蚀程度的不均一性使不整合有3种典型岩石组合：底砾岩-风化壳-淋滤带型，主要分布在断裂带北部，呈条带状分布，底砾岩滞留原地，风化壳保存较好，淋滤带发育；水进砂体-风化壳（风化黏土）-淋滤带型，因湖侵导致的远物源搬运，砂层分选、磨圆度都很好；砂泥层-风化泥岩型或砂泥岩叠合型，是多次水进水退形成的。构造部位不同、构造变形强度不同、沉积物源不同是造成不整合结构差异的主要因素。在此基础上，分析了不整合成因模式。乌尔禾夏子街地区与不整合有关的油藏众多，主要有削截不整合、断褶不整合形成的不整合面遮挡油气藏和超覆不整合形成的地层超覆油气藏。图9表1参23

Development of unconformity and its effect on the migration and accumulation of hydrocarbon in Wu''''erhe-Xiazijie area, Junggar Basin

There are multiphase unconformities in the Wu'erhe-Xiazijie area of Junggar Basin from Permian to Jurassic,including the truncation,onlap,fold,fault-fold and parallel unconformities.According to the heterogeneity of the weathering and erosion degree,the unconformities have three types of rock association:basal conglomerate-leached zone-argillic horizon,transgressive sands-leached zone-argillic horizon,and sand stone/mudstone zone-leached zone.The first type is distributed in the north of fault belt,in a narrow belt shape,with the basal conglomerate retained in situ,the weathering crust in good preservation,and the leached zone developed.The second type has good sorting and psephicity because of mass transport caused by lacus immersion.The third type is formed as a result of repetitious water immersion and reliction.The differences of sectonic position,tectonic movement,and provenance cause the different unconformity structures.Based on this,the genetic model of the unconformities is analyzed.The hydrocarbon reservoirs related to unconformities in the area include the unconformity screened and stratigraphic onlap reservoirs.