SAGD (steam assisted gravity drainage) steam injection system

The invention discloses an SAGD (steam assisted gravity drainage) steam injection system comprising a steam injection station provided with an inlet and an outlet and at least one steam distributor. The steam injection station comprises at least one boiler. Any steam distributor is communicated with the outlet of the steam injection station. Each steam distributor is provided with a plurality of steam injection lines. The SAGD steam injection system further comprises a plurality of steam trap valves close to a wellhead. The steam trap valves are in one-to-one corresponding communication with the steam injection lines. Each steam trap valve is provided with a drain outlet and a steam outlet; the drain outlet of every steam trap valve is communicated with the inlet of the steam injection station; the steam outlet of every steam trap valve is communicated with an oil well. The SAGD steam injection system with the structure has the advantages that dryness of high temperature steam entering the oil well can be increased, separated saturated water can be reused, and heat of the saturated water is reused.