大巴山前陆盆地形成及演化与油气勘探潜力分析

Analysis on tectonic evolution and exploration potential in Dabashan foreland basin

根据野外地质调查、地震资料解释以及大量岩心分析化验等资料 ,探讨了大巴山前陆盆地的形成及演化 ,分析了油气勘探潜力。研究结果表明 ,大巴山前陆盆地形成始于燕山中幕 ,盆地演化经历了J1 J12 陆内坳陷湖盆阶段、J22 J3 前陆盆地阶段、K1 N盆地萎缩阶段以及喜马拉雅期最终定型阶段。大安寨段和凉高山组两套优质烃源岩的有机质丰度高 ,有机质类型以Ⅱ1型和Ⅱ2 型为主。侏罗系发育大安寨段、凉高山组自生自储型和下沙溪庙组下生上储型 3套生储盖组合。有利勘探区带包括大巴山前冲断带、川北凹陷带和川中低隆起带。

On the basis of outcrop survey, seismic interpretation and a lot of coring data, the evolution and exploration potential of Dabashan foreland basin were analyzed. This foreland basin was formed in the mid-Yanshan cycle and underwent four stages including J1- J21 depression stage, J22-J3 foreland basin stage, K1-N basin shrunk and final deformation of thrust-folded end in Himalayan period. In this basin, two sets of high-quality resource rocks developed in the Daanzhai Formation and Lianggaoshan Formation have high abundance of organic matters which mainly contain II 1 type and II2 type kerogen. The favorable assemblages of source-reservoir-cap rocks in Jurassic include self-generated and self-reservoir type Daanzhai Formation and Lianggaoshan Formation as well as lower-generated and upper-reservoir type lower Shaximiao Formation. The favorable plays include the thrust belt in Dabashan area, sag in the north Sichuan province and uplift in the central Sichuan province.