The installation of offshore pipelines from a lay barge can be difficult, costly, and time-consuming. The barge generally proceeds along the pipe lay-path via winches that pull in on preplaced anchors positioned ahead of the barge. As the barge draws up to these anchors, the anchors must be periodically moved ahead and reset. Dynamically positioned ocean-going vessels temporarily equipped with coiled tubing (CT) equipment can help operators greatly reduce the complications associated with laying offshore flowlines. Recently, a service company specializing in coiled tubing operations worked with a major operator to lay continuous strings of 3,000 to 5,000 ft of large-diameter, coiled tubing flowlines between several offshore platforms in the Arabian Gulf. Modified CT well-service equipment was installed on a vessel equipped with dynamic positioning (DP) capabilities. A remote-operated-vehicle (ROV) and sonic transponders allowed operators to determine the location of the flowlines as they were placed on the seabed. Using this approach, operators successfully laid three lines in significantly less time and at a significantly smaller expense than would have been required by conventional barge-lay methods.

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