Wanjinta CO

2

field is located on the western margin of Dehui depression

Songliao Basin.The gas pooled in the Middle Cretaceous Quantou Formation

and is trapped in anticline and stratigraphy-fault-aticline complexities.Thewell yield is more than 20

000m

3

of gas per day.The gas comprises 84.5-99.8% of CO

2

and a little hydrocarbons.Eachgas pool has its own specific hydrodynamic system.Due to its gravity differ-entiation

the content of hydrocarbon decreases and that of CO

2

increases withdepth.The reserve of gas field is quite voluminous and productive.On the ba-sis of δ

13

C value and regional condition

it is suspected that CO

2

was de-rived

and then concentrated

from magmatism.The Early Cretaceous vol-canics to which the Well Wan-5 penetrated more than 939m thick.