Process for running scrapers, particularly for subsea petroleum well

Abstract

A process for running scrapers for subsea petroleum well lines has, according to a first embodiment, launching of a scraper through the line to be disobstructed, towards the wellhead on a step-by-step basis. The operation proceeds by sending the scraper along successively larger sections via reversing flow through the obstructed line to limit passage of the scraper to that obstructed line, until the whole line is swept. Furthermore, according to a second embodiment, the process consists of the launching of one or more scrapers from a chamber installed in the subsea production system, towards the platform, sweeping only the whole obstructed line, all at once. Preferably one or more scrapers are launched from a chamber installed in the subsea equipment towards the surface platform and sweeping the entirety of a first obstructed line. Once cleaning of the obstructed line is completed, new scrapers may be sent from the platform to the subsea equipment chamber where they are stored until a further cleaning operation is required. The chamber installed in the subsea equipment may serve more than one obstructed line.