自生伊利石K-Ar测年在焉耆盆地油气成藏研究中的应用

APPLICATION OF AUTHIGENIC ILLITE K-AR DATING TO HYDROCARBON RESERVOIRING STUDY IN YANQI BASIN

李永林 卜翠萍 南红丽 宋建华

Li Yonglin Pu Cuiping Nan Hongli Song Jianhua

储层中自生伊利石K-Ar年龄测定表明,焉耆盆地博湖坳陷油气充注时间大致分为两个时间段即两次成藏期:晚白垩世(107.8～67.8Ma)和始新世后(51.3～34.8Ma)。平面上各构造成藏期不尽相同,北部凹陷由南往北油气成藏时间依次变晚,宝南和宝中区块油藏形成于晚白垩世,油气来自晚燕山期的产物。宝北区块油藏形成于渐新世,油气来自于宝中区块原生油气藏的调整及喜山期的二次成烃。南部凹陷成藏期为晚白垩世晚期。纵向上同一构造带内,K-Ar年龄随埋深减小而变小,反映油气自构造低部位向构造高部位逐渐充注运移和调整。

K-Ar dating results of authigenic illite in reservoirs indicate that charging time of gas in Bohu sag,Yanqi basin,might have roughly been divided into two phases:one is in 107.8～67.8 Ma,corresponding to Late Cretaceous;another is in 51.3～34.8 Ma,being equal to post-Eocene. Horizontally,various structures have different reservoiring stages.The reservoiring time has successively been later and later from south to north in the northern sag.The reservoiring in south and middle blocks of Baolang reservoir might have occurred in Late Cretaceous,and oil and gas have been generated in late Yanshan period;while reservoiring in north block of Baolang reservoir have occurred in Oligocene, and have been sourced from both the readjustment of primary reservoir in middle block and secondary hydrocarbon generation in Himalayan period.The reservoiring time in the southern sag might have been in later stage of Late Cretaceous.Vertically,the K-Ar dating indicates that the reservoirs in the same structural belt are younger with less buried depth,which mean that oil and gas have migrated upwards,and shallower structures have been charged from the readjustment of deeper structures.

10.11743/ogg20030216