江汉盆地气藏特征及成因

FEATURES AND GENESIS OF GAS RESERVOIRS IN THE JIANGHAN BASIN

江汉盆地是在扬子准地台上发育起来的白垩系—古近系断陷盆地,也是我国陆相盆地中典型的含盐含油气盆地。长期以来,在该盆地的油气勘探一直以找油为主,近年来钻探的潭32井在新近系广华寺组发现了气藏,日产气13.53×104m3,这是在该盆地白垩纪—新近纪地层中首次发现的天然气藏。为此,利用气体组成,碳、氢同位素等资料在分析已知油区油藏伴生气和潭32井区气藏天然气地化特征的基础上,对比研究了其天然气成因,进而得出结论:江汉盆地所发现的气藏气和油藏伴生气都属于有机成因的油型气,迄今为止在该盆地内未发现无机气和有机成因的煤型气。

The Jianghan basin is a Cretaceous-Paleogene rifted basin developed on Yangtze paraplatform and also a typical continental petroliferous basin containing salt layers. The exploration activities are focused on oils for quite some time. The well Tan-32 drilled recently has obtained a gas discovery in the Neogene Guanghuasi Formation, with a tested gas flow of 135 300 m3/d. This is the first discovery of natural gas in the Cretaceous-Paleogene in the Jianghan basin. The genesis of the gas is studied based on correlation of the geochemical features between the existing associated gas reservoirs and that in Tan-32 wellblock by using the data of gas component and isotope like carbon and hydrogen. It is concluded that both the gas in the gas reservoirs and the gas in the associated gas reservoirs are oil-related gas in the Jianghan basin, and no abiogenetic gas or biogenetic coal-related gas have been discovered in the Jianghan basin.