Abstract: Hangjinqi area is one of the major gas exploration targets in Ordos Basin.Analyses of occurrence characteristics,composition and homogenization temperature of fluid inclusions from Hangjinqi area were carried out to identify the main gas reservoiring stages and timing.The results show that fluid inclusions from the Upper Paleozoic Hangjinqi area are mostly distributed in quartz overgrowth or healed fractures of pebbly sandstone,medium-grained and fine sandstones.Two stages can be identified with gas/liquid hydrocarbon inclusions and gas/liquid brine inclusions dominated.They can be oval,sub-prismatic,long strip,semicircular,and irregular in shape with carbon dioxide and methane as the dominant gas components.The homogenization temperature distribution of brine inclusions,associated with hydrocarbon inclusions,has a wide range and multiple peaks.Samples from three plays,namely the Shilijiahan,Xinzhao,and Shiguhao,in the area,show a remarkable disparity in their homogenization temperature distributions.By projecting the homogenization temperatures of the inclusions from the plays on the paleo-geothermal field evolution history of the area and analyzing the thermal evolution history of source rocks,we suggest that the primary reservoiring stage of Shilijiahan play is from the Eocene to the present.The Xinzhao play also has its primary reservoiring period from the Eocene to the present,but there is the possibility of a secondary reservoiring stage ranging from late Early Jurassic to middle Late Jurassic.The reservoiring stage in the Shiguhao play is still from the Eocene to the present based on inclusion temperature data and gas migration characters.

Key words: reservoirng stage, fluid inclusion, Upper Paleozoic, Hangjinqi area, Ordos Basin