Patent ID: 6817422
Filing Date: 2004-11-16
Classification: E21B

Abstract:
An automated riser recoil control system, wherein the riser is suspended from a heaving vessel having a heave velocity, comprising:a plurality of riser tensioners in mechanical communication with the vessel and the riser, wherein each one of said plurality of riser tensioners applies a corresponding individual tension force to the riser under heaving conditions, and wherein each one of the corresponding individual tension forces is substantially proportional to the rate of at least one fluid flow within a corresponding tensioner, and wherein each one of the corresponding tensioners includes a tensioner piston travel indicator adapted to provide a piston travel signal; a vessel heave measurement system for measuring the heave velocity; a processor in electrical communication with each one of the tensioner piston travel indicators and the vessel heave measurement system so as to monitor each one of the piston travel signals and the heave velocity signal, and in controlling communication with each one of the plurality of riser tensioners so as to control the rate of the at least one fluid flow within at least one of the plurality of tensioners upon determining that a preselected number of piston travel velocities determined from each one of the plurality of piston travel signals exceed the heave velocity by a preselected critical velocity difference; and, wherein at least one of the plurality of riser tensioners includes an air shutoff valve, further comprising a first timer adapted to delay closure of the air shutoff valve for a preselected first delay time period after determining that the preselected number of piston travel velocities determined from each one of the plurality of piston travel signals exceed the heave velocity by the preselected critical velocity difference.