松辽盆地徐家围子断陷火山活动期次与烃源岩演化

徐家围子断陷在断陷期有3次较大规模的火山活动,营城期火山活动持续时间最长。火山活动加速了深层火石岭组、沙河子组、营城组3套主力烃源岩的成熟。烃源岩的埋藏史、热史和生烃史模拟计算结果表明,徐家围子断陷深层火石岭组烃源岩埋深1300 m的R_o值,在约1Ma 时间内迅速达到0.7%。沙河子组以及火石岭组烃源岩埋深约2600 m时,R_o值已经达到1%。泉头组沉积前,沙河子组及火石岭组烃源岩已进入生气高峰。青山口组沉积前,营城组烃源岩处于生气高峰,沙河子组以及火石岭组开始生成干气。此时,登娄库组二段和泉头组一、二段区域盖层业已形成,徐家围子断陷开始形成营城组—泉头组天然气藏。嫩江期末,由于边界断层的活动,营城组—泉头组天然气藏进行再分配。

Volcanic activities and evolution of source rocks in Xujiaweizi fault depression, Songliao basin

Xujiaweizi fault depression has experienced three relatively large volcanic activities during rift fauting,a- mong which the volcanic activity duing the deposition of Yingcheng Fm had the longest duration.The volcanic activity speeded up the maturation of the major source rocks including deep Huoshiling Fm,Shahezi Fm and Yingcheng Fm. Simulations of burial history,thermal history and hydrocarbon generation history show that the R_o value of Huoshiling Fm source rocks at a burial depth of 1 300m would have rapidly reached 0.7% in about 1Ma.The R_o value of Sha- hezi and Huoshiling Fins source rocks would have reached 1% at a burial depth of 2 600m.Before the deposition of Quantou Fm,Shahezi and Huoshiling Fins source rocks would have entered the peak of gas generation.Before the de- position of Qingshankou Fro,Yingcheng Fin source rocks would have been in the peak of gas generation,while Sha- hezi and Huoshiling Fms source rocks would have begun to generate dry gas.At this time,the regional seals of the 2~(nd)member of Denglouku Fm and the 1~(st) and 2~(nd)members of Quantou Fm would have been formed,leading to the for- mation of gas pools in Yingcheng-Quantou Fms.By the end of the deposition of Nenjiang Fm,the movement of bound- ary faults led to the redistribution of gas pools in Yingcheng-Quantou Fms.