How to operate wellhead Christmas tree　
　　1、 Well opening (flowing well): 1. Ensure that the production system is complete, the flow is smooth, and the fluid after well opening can be accepted. 2. All valves on the Christmas tree are in the correct on / off state to control the nozzle (adjustable nozzle). 3. Check the status of wellhead oil pressure equipment.
　　2、 Shut in (blowout): 1. Shut in the choke. 2. Close the wing valve. 3. Close the ground valve if necessary. 4. Close the main valve if necessary.
　　3、 In some downhole operations, the operation steps of Christmas tree valve are as follows:
　　1. Shut in the well (nozzle, wing valve, paraffin removal valve, surface valve and main valve) before running downhole tools.
　　2. Open the cap of Christmas tree, install the riser and BOP, and then test the pressure of riser.
　　3. Open the ground valve and lock the ground valve with a fusing screw cap. In the open position, test the reliability of the locking screw cap.
　　4. Lock the hydraulic control circuit of downhole valve and test its reliability.

　　5. Open the main valve and then the paraffin removal valve.
　　6. Put labels on the main valve, paraffin removal valve and valve locking position to prevent other personnel from moving the valve casually.
　　7. Running tools into the well.
　　8. Close the main valve and paraffin removal valve after the downhole tools are lifted to the riser.
　　9. After pressure relief and removal of BOP riser, install Christmas tree cap,
　　10. Remove the locking screw cap of the surface valve, open the hydraulic locking valve of the downhole valve, and remove the label,
　　11. Open the well for production according to the instruction.