Since Saudi Aramco's seawater injection system was commissioned in 1978, it has undergone a series of expansions and modifications. The system is unique, not only in its size (7 million barrels per day capacity), but also in its complicated piping network. While the original piping system was completely made of bare carbon steel, the new system is made of pipe which is internally coated with fusion bonded epoxy (FBE).
Saudi Aramco's field experience in the past ten years with its seawater injection system has demonstrated the benefits of internally coated pipe. This paper explains why Saudi Aramco decided to use internally coated pipe, which is not a standard practice in the oil industry. Saudi Aramco has two objectives: minimizing water quality deterioration and controlling internal corrosion. First, despite the stringent solids and oxygen removal processes at the intake, water quality always deteriorates as it travels through the pipe. This water, upon arrival at some remote injection wells 250 to 300 kilometers away and 36 hours later, could cause excessive injectivity decline of the wells. Second, internal corrosion generally has not been a problem for uncoated lines, if they are regularly scraped and treated with bactericide for control of microbiologically influenced corrosion. However, uncoated lines which are unscrapable and untreatable require extra corrosion protection.
This paper also discusses the technical challenges concerning coating applications, particularly for coating girth-weld areas in the field. It also discusses scraping requirements for internally coated pipelines, which remains a controversial topic.
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