楚雄盆地洒芷古油藏成藏与破坏主控因素

Major controlling factors for oil accumulation and destruction in paleo-reservoirs,Sazhi area,Chuxiong Basin

彭金宁 刘光祥 吕俊祥

Peng Jinning Liu Guangxiang L? Junxiang

楚雄盆地自下寒武统至白垩系,在多处发现油气苗和沥青显示。研究认为,导致洒芷古油藏破坏的主要因素是晚期构造隆升与大幅度的剥蚀,它们使得古油气藏暴露地表;晚期挤压冲断伴生的张性破裂缝窜通地表,使油气散失也是一个不可低估的破坏因素。油藏孔隙类型主要有两种:下部主要为原生型孔隙(上三叠统);上部主要为裂缝型孔隙(侏罗系)。下部的孔隙型沥青是早期成藏的岩性-地层油气藏的残迹。这说明斜坡区、隆起区是油气运移的长期指向区,有利于古岩性-地层油气藏的形成。

Oil and gas seepages and asphalt shows are not rate from the Lower Cambrian to the Cretaceous in the Chuxiong Basin.An analysis of Sazhi plaeo-reservoirs in the basin reveals that they were destroyed mainly because of surface exposure caused by later structural uplifting and large-scale erosion.Extensional fractures induced by later compression and thrusting connected the reservoirs with the surface and therefore also contributed a lot to the destruction of the reservoirs.There are two types of reservoir space.One is original pores which dominate the lower part of the reservoir(the Upper Triassic),and the other is fractures which are predominant in the lower part of the reservoir(the Jurassic).Bitumen occurring in the pores of the lower reservoir interval is believed to be the remnant of early-formed lithologic-stratigraphic reservoirs,indicating that the slope and uplift zones are the favorable places for the formation of paleo-lithologic-stratigraphic reservoirs as they are regarded as the final destination of oil and gas migration.

10.11743/ogg20090615