Stuffing box for a fluid production well, and associated surface assembly

A stuffing box for a fluid production well, the stuffing box defining a circulation passage of a cable working line extending between an upstream end of the stuffing box, intended to be 5 connected to the well, and a downstream end, the stuffing box including at least one packer arranged in the passage to ensure the sealing between an upstream portion and a downstream portion of the passage when the line is inserted in the passage, the stuffing box including a back-pressure resistant valve arranged in the passage to prevent the back-pressure of a fluid from the upstream end towards the downstream end, wherein the packer is situated between 10 the upstream end of the stuffing box and the back-pressure resistant valve, no packer being arranged between the back-pressure resistant valve and the downstream end. 71048351 (GHMatters) P91767.AU.1 JINGT 10/11/15 WO 2011/134637 PCT/EP2O1I/002179 co LfDO 0,4-