Except
Chapters 12-17 are a progression according to the order of approach to God in the tabernacle types: chapter 12, in which Christ speaks of His death, answers to the brazen altar of burnt-offering, type of the cross. Passing from the altar toward the holy of holies, the laver is next reached (Exodus 30:17-21); answering to Chapter 13. With His associate priests, now purified, the High Priest approaches and enters the holy place, in the high communion of Chapters 14-16. Entering alone the holy of holies (John 17:1); the High Priest intercedes.
Compare (Hebrews 7:24-28).
That intercession is not for the salvation, but the keeping and blessing of those for whom He prays. His death (assumed as accomplished), (John 17:4) has saved them.