OFFSHORE UNDERWATER OIL PLATFORMS FOULING and CLEANING
The offshore oil platforms’ bearing parts’ fouling problem becomes of especial importance due to oil and gas recovery increase today. Growth of gas and oil exploration drilling and producing offshore platforms’ (OOGP) number on the ocean shelf is accompanied with increase of their failures’ number, being basically related with the storms and oil release from the wells.
Intensive fouling growth on the offshore oil and gas platforms’ underwater parts causes unpredictable and unforeseen biological clogs of the oil and gas recovery platforms’ operation:
- Occurrence of additional load on the footings due to the gradually increasing fouling mass – by the averaged fouling specific weight accepted to be 20 kg per 1 sq.m., the total weight of the fouling on one footing on the depth to 50 m from the surface comprises at least 3 tons.
- Increased windage, i.e. increase of the footing resistance against the wave loadings – on the platform operated longer than a year, the fouling rate is very high, and the of the footing resistance against the wave loadings –increases for more than 50%
- Impossibility to reveal the active corrosion areas, external cracks and footings’ damaged constructive elements when conducting scheduled operations on their condition monitoring, since they are hidden with the thick fouling layer
- Control methods’ complicacy – supersonic, radiographic, magnetic particles’ methods; these methods either require the surfaces to be previously thoroughly cleaned up, or they are hazardous for human’s health.
One of the basic causes of the offshore gas and oil recovery platforms’ failures is the damaging of the bearing constructions caused by the biological fouling – barnacles, shells, and corals. Only the casualty of the offshore platform "Alexander Kielland" in the North Sea had resulted in 123 victims. One of the biggest failures was the destroy of the «Ocean Ranger" platform, which had failed during the storm with the parameters comprising only two thirds of the designed values, became one of the biggest offshore oil platform failures. The key role in this failure belonged to the fouling, which had not been taken into account.
Fouling of the offshore oil and gas producing platforms’ footings and bearing constructions presents a serious danger: it results in mechanical failures and emergency situations appearance, due to what mandatory scheduled inspections of underwater parts of the platforms and their following cleaning of the biological fouling have been introduced by all oil producing companies.
The specialized CAVI-JET EQUIPMENT allows to remove quickly and in a safe manner fouling of any hardness and thickness from the underwater constructions of the oil and gas producing platforms of any type and bigness.