四川盆地侏罗系致密油二次运移机制与富集主控因素

Secondary migration mechanism and accumulation controlling factors of Jurassic tight oil in Sichuan Basin

运用成藏物理模拟实验、铸体、荧光薄片、场发射和环境扫描电镜分析了四川盆地中部侏罗系致密油的二次运移机制和富集主控因素。研究揭示致密油在巨大的运移动力作用下,在低效运移通道中以低速非达西流运移,并依次经历'滞流'、'非线性流'、'拟线性流'3个运移渗流阶段,呈现微观上孔、缝复合输导,宏观上大范围短距离运移的运移模式。致密油有利区带的展布受优质烃源岩的分布控制,生烃强度4.0×105t/km2是研究区致密油有利区带分布的边界,孔隙度和渗透率较高的储层形成致密油甜点,高产井则与裂缝的发育程度关系密切。

Accumulation physical analog experiment,cast and fluorescent thin sections,field emission scanning electron microscope(FESEM)and environment scanning electron microscope(ESEM)were utilized to study the secondary migration mechanism and accumulation controlling factors of Jurassic tight oil in central Sichuan Basin.It was revealed that under the huge migration driving force,tight oil in the study area migrated with low speed non-Darcy flow through a low efficient migration path,and underwent three migration and seepage phases,including viscous flow,nonlinear flow,and quasi-linear flow.The mode was characterized by microscopic pore-facture complex conduction and macroscopic large-scale short-distance migration.Based on the migration mechanisms,the favorable tight oil play was controlled by the distribution of profitable source rocks.The hydrocarbon generating intensity of 4.0×105 t/km2 indicated the distribution boundary of favorable tight oil play in the study area.High permeability and porosity reservoir formed tight oil sweet spots,and high-capacity wells were closely related to the development of fracures in a majority.