Abstract:

 Wuerxun depression is one of the sags with the most abundant oil and gas resources in Hailer basin, Inner Mongolia, but the characteristics of geothermal field of this depression have not been researched. The characteristics of present geothermal field in Wuerxun depression was analyzed according to the continuous temperature data of 5 wells and reservoir temperatures of 42 wells and heat conductivity data. The present geothermal gradient is 28-37 ℃/hm with average value of 335 ℃/hm; the present heat flow is 422-594 mW/m2 with average value of 560 mW/m2. This result shows that Wuerxun depression has middletemperature field; the present geothermal gradient and heat flow in the north of the depression are higher than those in the south, which are mainly caused by the activity of the ground water and fault and volcanic rock. The present temperature is an important control factor on oilgas generation of source rocks. The Wuerxun depression has undergone continuous burial with increasing temperature, and the present temperature is the maximum temperature that the source rock has experienced; the present temperature in the west is the maximum, which causes the source rocks in Tongbomiao, Nantun and Damoguaihe formations in a high temperature environment, thus the source rocks is still in the stage of oilgas generation now, so the west area is the main oilgas exploration region in the Wuerxun depression.

Key words: geothermal gradient, heat flow, control factor, Hailaer basin, Wuerxun depression