In simple terms, oil and gas installations are in place in order to extract hydrocarbons from a reservoir and then transport them elsewhere to be processed for use. However, doing so requires considerable amounts of process equipment and infrastructure, including systems to help lift hydrocarbons from the reservoir, equipment to clean and process them for transport, and facilities for personnel to work and live.
Prior to any removals, the facilities on the platform and pipelines used to recover and transport the hydrocarbons must be de-energised. This involves ensuring any pressure sources are removed and that the installation is free — as far as reasonably practicable — of hydrocarbons and contaminants.
Topsides cleaning activities involve the flushing of process equipment from wells and pipework. It may also include entering pressure vessels on the installation to manually clean or to remove any solid material. The level of cleaning required on an installation depends on the removal methodology, as there may be opportunities to carry out much of the cleaning and decontamination as part of the onshore disposal.
Pipeline cleaning programmes are designed to ensure the hydrocarbon content and any deposits within the pipeline are dealt with, taking into account the future Decommissioning Programme and without prejudicing any opportunities for potential reuse.
Teams of operational specialists are required for these de-energising work scopes. For some of the cleaning activities, sophisticated strategies are developed to achieve the required levels of cleanliness. It is beneficial to have personnel with knowledge of the specific installation involved in these activities, when specific knowledge of
the asset’s facilities can ensure a successful campaign.