Methods of remotely facilitating the transition between flooding and hydrotesting a subsea pipeline include a control unit of a subsea valve actuation system closing off fluid flow out of the pipeline at the receiving end thereof based at least partially upon one or more signals emitted by at least one intelligent pig that has passed through the pipeline during flooding and without the involvement of an external source at the surface, or a UV, at the pig receiving end of the pipeline.

Methods of remotely facilitating the transition between hydrotesting and dewatering of a subsea pipeline include a control unit of a subsea valve actuation system determining when hydrotesting of the pipeline has been completed and autonomously allowing fluid flow out of the pipeline at the receiving end thereof without the involvement of an external source at the surface, or a UV, at the pig receiving end of the pipeline to allow dewatering the pipeline from the launch end of the pipeline.

There is provided an apparatus for tracking a pig travelling inside a tubular object. The apparatus includes a sensor arrangement including at least one position sensor configured to detect a passage of the pig travelling inside the tubular object and a tracking device. The tracking device is configured to: process the detected passage of the pig from a run of the pig through the tubular object to determine a travel time of the pig; using the determined travel time, calculate a speed of the pig through the tubular object; and using the calculated pig's speed, perform real-time tracking of the pig's position inside the tubular object in a subsequent run of the pig through the tubular object.