This week, I attended a useful meeting in Wareham for local Councillors with Perenco, who run the Wytch Farm oil field, where we learned much more about the recent Oil leak and what they have been doing to investigate and prevent recurrence.
There are 12 sites within the oilfield, with 106 wells. This is a mix of injectors (water pumped into them) and producers (a mix of water and oil pumped out, roughly 97% water). The wells go to about 1Km deep. These sites are then connected by a network of distributer pipes, buiried at least 1.5M deep, and it was one of these that failed.
At its peak, BP were extracting 110,000 barrels of oil per day. Perenco are now getting 9-10,000 barrels, less than 1/10th of the volume. They have 3 sets of pipelines between the sites, bringing the water/oil mix back to the main centre where it is separated. These are 12”, 10” and 8” diameter respectively, and the hole appeared in the largest pipeline. There are also other pipes returning water to the ground. There is then a 16” pipe that takes the separated oil across the New Forest to Fawley. The pipes are inspected internally every year using an imaging device that traverses along them. They also use regular helicopter inspections (the pipeline to Fawley is 92Km long).
The water content of the mixture varies in salinity. The oil from the Goathorn well is the most saline, closest to the sea, the water from the other sites less so. The salinity controls bacterial growth, and what they’ve found is that at the break location, the mix latterly passing along the pipe with reduced salinity, and a slow flow rate, gave the perfect conditions for rapid and unexpected bacterial growth on the steel pipe, which pierced the wall between inspections. This grew from a pinhole to a 20mm hole when it was detected. The whole oilfield operation was closed down until they had clarity and permission to restart.
So what are they doing to prevent recurrence ? They talked of renewal of a number of pieces of kit that are now oversized to their current operations. They have retired this largest distributer pipe from use. The smaller distributer pipes have been internally lined with plastic/GRP pipes. They use cathodic protection for the pipelines (electrically charging the steel), which will continue for the unused pipework.
The current permissions for Oil extraction are to 2037, when everything at surface would be gone. There are a whole raft of different permissions, and the first well site to go will be the one at Arne, which they are already planning for. As a company, Perenco are looking at carbon capture and renewable energy for the future.
There was other detail shared, including around their land and heathland management (they rent 500 Acres of land, mostly from the Rempstone Estate), and their moves to using renewable energy. I found it helpful to hear directly from those involved. They did say that they just as others, live locally, and care hugely about the harbour and environment. Having the leak had been hugely challenging for them.
As I understand, the Health and Safety Executive, and the Environment Agency are both still deliberating on whether any regulatory action may arise. They were not at the meeting.
Cllr Andy Hadley, BCP Council. January 2024