焉耆改造型盆地特征及其油气勘探方向预测

焉耆盆地是中、新生代的叠合、改造型盆地，中生代为类前陆盆地，之后虽经历了燕山运动中晚期的冲断、隆升剥蚀和喜山期的长期改造，但盆地构造格局并没有发生改变。烃源岩以煤系地层为主，主生烃期为燕山期末，喜山期生烃贡献不明显；圈闭类型多样．多与冲断活动有关，形成于燕山期。定型于喜山期；燕山期末已存在的圈闭成藏条件较好，但控制圈闭的断层在喜山期活动与否及其活动强度，决定着燕山期形成的油气藏能否保存；喜山期形成的构造圈闭及地层圈闭的油气来源有限，盖层条件较差,油气成藏条件欠理想。下步勘探方向应以与燕山期末主生烃期相配置的构造圈闭和岩性圈闭为重点。

Characteristics of Reconstruction Basin in Yanqi Area and Direction Prediction of Oil and Gas Exploration

Yanqi basin is an overlapping and reconstruction basin in Mesozoic and Cenozoic eras, in Mesozoic era it is a foreland-like basin, undergoes thrust, uplift, and erosion at middle and late Yanshan Movement, and reconstructs during Xishanian, while the structural pattern of the basin does not change. Source rock is mainly coal-measure strata with property of early generation and early expulsion. Hydrocarbon generation is mainly at the end of Yanshanian, while hydrocarbon generation during Xishanian is not evident. Many trap patterns exist in the basin, and most of them are related to thrust faulting, which forms during Yanshan period and shapes at Xishanian. Hydrocarbon reservoir forming is favorable for the traps existed at the end of Xishanian, yet the fault of controlled trap during Xishanian determines reservoir preservation formed during Yanshanian. Structural traps and stratigraphic traps formed during Xishanian are poor for oil and gas potential , and forming condition for cap rock and reservoir are unfavorable. Exploration strategy for next step is mainly in structural traps combined with lithologic traps at the end of Yanshan period.