Traditionally, when changing drilling product to specialist mud, mud lines are flushed with water, brine or base oil until they are clear of contamination and purged with compressed air. This process produces vast quantities of waste prior to tank cleaning. Treating the waste water which is produced has a negative impact on the environment and is costly.
AMS Global Group developed a process for flushing pipes utilising technology from other industries. The system uses Rotorjet cleaning heads in the mud lines and pushes waste up the manifold to a high vacuum tanker on the quayside. The aim was to minimise the volume of waste water produced and subsequently treated, to reduce the environmental impact and achieve significant savings in cost and time.
A practical assessment and comparison was conducted on a North Sea PSV which berthed in Peterhead on November 2019, to discharge 2610 bbls (415m3) of water-based mud from four vessel tanks to shore. The Rotorjet system was put to the test by comparing it to traditional practice flushing. Time taken and waste water produced by both systems was noted for comparison. Borescopes were used after cargo discharge; after purging the lines with air; after Rotorjet cleaning to compare the cleaning methods.
Data comparison showed the following results:
- Time flushing: Traditional flushing – 3hours; Rotorjet Cleaning – 1 hour
- Length of line: Traditional flushing – 22m; Rotorjet Cleaning – 22m
- Waste produced: Traditional flushing – 10mt; Rotorjet Cleaning – 3mt
Using the Rotorjet system compared to traditional flushing methods is projected to achieve the following results:
Costs reduced by up to 50% per vessel
- Cost of waste water processing by traditional flushing, approx. £54,000p/a; cost of waste water processing by Rotorjet cleaning, approx. £26,000p/a
Significant time reduction
- Traditional line flushing can take up to two days; high vacuum and Rotojetting can take as little as 6 hours for 6 mud tanks
Up to 50% reduction in waste water produced
- Manually flushing lines can create up to 50m3 (315bbls) of waste water / Brine / Base oil; Rotorjet with a flushing fluid for non-accessible lines and pumps produces approx. 15m3 (94bbls) of waste water