长岭断陷断层活动特征及控藏作用

松辽盆地长岭断陷气藏类型多样，其分布特点与断层活动息息相关。为此，基于盆地构造演化背景，利用伸展正断层生长指数(EI)、断层垂直断距—埋深(T-Z)曲线、反转断层反转率(RI)和滑移距离曲线分析断裂活动时期和活动强度，划分断层类型，分析不同类型断层对成藏的控制作用。研究表明：1长岭断陷发育断陷期活动、断陷期—拗陷期活动和长期活动(断陷期—坳陷期—反转期持续活动)的弱反转、强反转四种类型断层；2断陷期断层控制沙河子组烃源岩和营城组火山岩储层分布；3断陷期—拗陷期断层不仅控制烃源岩及火山岩储层的分布，还可在源内作为中、下部气藏组合的油气输导断层；4长期活动弱反转断层断陷期控制烃源岩分布，在拗陷期可作为油气输导断层，反转期控制浅层圈闭的形成并对气藏进行调整；5长期活动强反转断层对拗陷期形成的天然气藏具有破坏作用，该类断层附近难以形成规模天然气聚集。该成果对于松辽盆地南部深层天然气勘探具有指导作用。

Characteristics of fault activity and its effect on na-tural gas accumulation in Changling fault depression

There are various types of gas reservoirs in the Changling fault depression of Songliao basin, and their distribution characteristics are closely related to fault activity. Therefore, against the tectonic evolution background of the basin, the expansion index(EI) of the extensional normal fault, throw-depth (T-Z) curve of the normal fault, inversion rate (RI) of the reverse fault, and the slip-distance curve are used to analyze the fault activity period and intensity for further classification of fault types and the analysis of the different control effects of different faults on gas accumulation. The results reveal that ①the Changling fault depression has developed four types of fault systems: the faults active in the rifting period, the faults active during the rifting-depression period, long-term (continuous activity from the rifting-depression period to the inversion period, the same below) active weak reverse faults, and long-term active strong reverse faults. ②Faults formed during the rifting period control the source rock of the Shahezi Formation and the volcanic reservoirs of the Yingcheng Formation. ③Faults active in the rifting-depression period not only control the distribution of source rock and volcanic reservoirs but also serve as oil and gas transport faults of the middle and lower gas reservoir combinations when they are in the source. ④Long-term active weak reverse faults control the distribution of source rock during the rifting period, act as transport faults during the depression period, and control shallow traps and adjust the gas reservoirs in the inversion period. ⑤Long-term active strong reverse faults can destroy the natural gas reservoirs formed in the depression period, and thus it is difficult to form large-scale natural gas accumulation around such faults. The above conclusions can be used as a reference to guide nature gas exploration in the southern Songliao Basin.