Abstract: HYS Oilfield is the first area of thermal recovery for heavy oil in ultra-shallow formations in China,but it is hard to develop heavy oil from ultra-shallow reservoir by conventional thermal recovery.In order to enhance recovery,experiment of combined thermal carriers has been carried out.The first sets of tests are made by combined heat carrier and a small amount of steam,the effect is poor in displacement of oil;the second sets of tests are made by combined heat carrier,steam and foamer,with better results obtained.The testing results show that combined thermal carrier is mainly non-condensed gas,with low enthalpy value,requiring the assistance of steam to work well.Combined steam injection can prevent steam channeling,and produce scale effect,that is the best method of steam injection by combined heat carrier,and has obtained good effect in T2k formation of HYS Oilfield.Combined heat carrier technique can improve heavy oil displacement effect in ultra-shallow formations,enhance oil recovery,and provide guidance for its application in the future.