Claims
- 1. 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.
- 2. The automated riser recoil control system of claim 1, wherein the processor adjusts a selected one of the individual tension forces applied to the marine riser by controlling the rate of the at least one fluid flow within a corresponding tensioner.
- 3. The automated riser recoil control system of claim 1, wherein at least one of the piston travel signals is a piston distance travel signal.
- 4. The automated riser recoil control system of claim 1, wherein at least one of the piston travel signals is a piston velocity travel signal.
- 5. The automated riser recoil control system of claim 1, wherein at least one of the piston travel signals is a piston acceleration travel signal.
- 6. The automated riser recoil control system of claim 1, wherein at least one of the plurality of riser tensioners comprises an accumulator chamber and a piston bore chamber, and wherein the at least one fluid flow within the cable tensioner passes through the piston bore chamber.
- 7. The automated riser recoil control system of claim 1, wherein at least one of the plurality of riser tensioners includes an orifice-controlled fluid valve, further comprising a second timer adapted to delay closure of the orifice-controlled fluid valve for a second preselected 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.
- 8. The automated riser recoil control system of claim 1, wherein at least one of the plurality of riser tensioners includes a fluid volume speed control valve which acts to limit a volumetric rate of fluid flow in the at least one of the plurality of riser tensioners upon sensing a predetermined volumetric rate of flow in excess of a predetermined volumetric rate of flow.
- 9. A method for adjusting at least one tension force selected from a plurality of tension forces applied by a corresponding plurality of riser tensioners to a marine riser suspended from a heaving vessel, comprising the steps of:determining a plurality of piston travel velocities experienced by the plurality of riser tensioners; measuring a heave velocity experienced by the heaving vessel; calculating a plurality of velocity differences, wherein each one of the plurality of velocity differences corresponds to a difference between a selected one of the plurality of piston travel velocities and the heave velocity; adjusting the at least one tension force upon determining that a preselected number of the plurality of velocity differences exceed a preselected critical velocity difference; and, wherein at least one of the plurality of riser tensioners includes an air shutoff valve, and wherein a timer delays closure of the air shutoff valve for a preselected delay time period after determining that the preselected number of the plurality of velocity differences exceed a preselected critical velocity difference.
- 10. The method of claim 9, wherein at least one of the plurality of riser tensioners applies a corresponding individual tension force to the riser in proportion to a rate of at least one fluid flow within the at least one of the plurality of tensioners, and wherein the step of adjusting the at least one tension force is accomplished by throttling the rate of at least one fluid flow within the at least one of the plurality of riser tensioners.
- 11. The method of claim 9, wherein at least one of the plurality of riser tensioners includes a fluid volume speed control valve which acts to limit a volumetric rate of fluid flow in the at least one of the plurality of riser tensioners upon sensing a predetermined volumetric rate of flow in excess of a predetermined critical volumetric rate of flow.
- 12. The method of claim 9, wherein at least one of the plurality of riser tensioners includes an orifice-controlled fluid valve, and wherein a second timer delays closure of the orifice-controlled fluid valve for a second preselected time period after determining that a preselected number of the plurality of velocity differences exceed a preselected critical velocity difference.
- 13. The method of claim 9, wherein the selected one of the plurality of piston travel velocities is derived from a piston distance travel signal.
- 14. The method of claim 9, wherein the selected one of the plurality of piston travel velocities is derived from a piston acceleration travel signal.
- 15. The method of claim 9, wherein at least one of the riser tensioners comprises an accumulation chamber and a piston bore chamber, and wherein the at least one fluid flow within the cable tensioner passes through the piston bore chamber.
RELATED APPLICATIONS
This application claims the benefit under Title 35 of the United States Code §119(e) of U.S. Provisional Patent Application No. 60/204,442, filed May 15, 2000.
PCT Information
Filing Document |
Filing Date |
Country |
Kind |
PCT/US01/15623 |
|
WO |
00 |
Publishing Document |
Publishing Date |
Country |
Kind |
WO01/88323 |
11/22/2001 |
WO |
A |
US Referenced Citations (11)
Provisional Applications (1)
|
Number |
Date |
Country |
|
60/204442 |
May 2000 |
US |