Equipment for oil recovery can include three systems: a steam system, a carbon dioxide system and a nitrogen system. The three systems can include one or more of a steam pressure regulator, a steam thermometer, a steam pressure gauge, a steam flowmeter, a carbon dioxide pressure regulator, a carbon dioxide compressor, a carbon dioxide thermometer, a carbon dioxide pressure gauge, a nitrogen compressor, a nitrogen pressure regulator, a nitrogen thermometer, a nitrogen pressure gauge, assembled valves, a gas injection tube and a chemical agent valve. The three systems can be connected into a heavy oil well via the assembled valves, the gas injection tube and a down-hole tube. The equipment can integrate three pressurizing and metering systems of steam, carbon dioxide and nitrogen together. With the equipment, one, two or three of the gases may be injected into oil wells to achieve favorable results of output increase.