This paper concentrates on the challenges, experience and lessons learned during the Precommissioning and Commissioning (PCC) of the Blind Faith 14?? to 18?? gas export pipeline.
The PCC for the Blind Faith gas pipeline took place in 2008 and was an extremely challenging phase of the project. The challenges were associated with the complexity of the subsea architecture at the interconnection of the new Blind Faith gas pipeline and the existing Canyon Chief gas pipeline (Refer to OTC paper 19764 for the tie-in between Blind Faith and Canyon Chief systems). The complexity was further challenged by the need to minimize the amount of shut in days for the production of the Canyon Chief gas pipeline. The PCC occurred in two phases:
Phase I - Without shutting in existing production on Canyon Chief gas pipeline:
Hydrotest the Blind Faith gas pipeline
Dewater and inhibit the Blind Faith gas pipeline subsea by a pig train consisting of 4 pigs and three slugs of MeOH
Phase II - Shutting in existing production on Canyon Chief gas pipeline:
Blowdown the Canyon Chief gas pipeline (during blowdown, recover the gas rather than venting to atmosphere)
Dewater and inhibit an isolated two miles section in the Canyon Chief gas pipeline by the pig train from Blind Faith
Retrieve pigs and recover methanol at MP-261A
Restart Canyon Chief pipeline and provide buyback gas to Blind Faith
The PCC architecture and commissioning challenges included the following:
Deepwater GoM - up to 6800' fsw
Multiple pipeline diameters
Long pipeline distance
Limited nitrogen flow rate
Dewatering through a gas pipeline
Drying of gas pipeline
Limiting number of shutdown days for existing production
The PCC effort took approximately three months to complete, during which time the project experienced two back to back hurricanes and Phase I was performed twice due to pig related issues.
