Back to results
US 2026/0185586 A1Published application
System and method for improved heave compensation
AssigneeGrant Prideco, L.P.
InventorsDavid Bengt Johan Ankargren, Peter Gu
Life of this patent
Estimating the term…
Abstract
A damping system for a heave compensator for an off-shore oil rig includes a hydraulic cylinder having a piston and a housing. The hydraulic cylinder is configured for accepting a hydraulic fluid. There is a flow passage for restricting the flow of the hydraulic fluid during movement of the piston in the housing. The hydraulic fluid is a magnetic fluid and the damping system includes a magnetic fluid management system for controlling a magnetic field at the flow passage. A heave compensator including such a damping system, and a method for controlling the damping of a heave compensator are also disclosed, the method including subjecting a magnetic fluid to a magnetic field at a flow passage for restricting the flow of the magnetic fluid.
Claims20
A heave compensator for an off-shore oil rig, the heave compensator comprising:
- a damping system, comprising:
- a hydraulic cylinder configured for receiving a hydraulic magnetic fluid, and having a housing configured to couple to a first structure, a permanent magnet disposed within an interior of the housing, a piston disposed within the interior of the housing and configured to couple with a second structure, wherein the piston comprises an inductive coil inductively coupled to the magnet whereby electrical energy is generated in the inductive coil by electromagnetic induction in response to movement of the piston in the housing relative to the permanent magnet;
- and
- a flow passage for restricting flow of the hydraulic magnetic fluid during movement of the piston in the housing, the movement of the piston in the housing urging the hydraulic magnetic fluid through the flow passage to damp relative motion between the first structure and the second structure when the housing is coupled to the first structure and the piston is coupled to the second structure, wherein the damping of the relative motion between the first structure and the second structure is adjustable in response to altering the viscosity of the hydraulic magnetic fluid by an electromagnetic coil in the piston;
- and
- a magnetic fluid management system (MFMS) in signal communication with the damping system, wherein the MFMS is configured to occupy an energy harvesting mode configured to allow the flow of electrical energy from the inductive coil whereby electrical energy is supplied by the inductive coil and then be reconfigured to occupy a damping mode configured to supply the electromagnetic coil of the damping system with electrical energy to selectively alter the viscosity of the hydraulic magnetic fluid as the piston strokes through the housing to minimize variations in damping force applied to the second structure;
- wherein, in the damping mode, the MFMS is configured to decrease the damping force as the piston increases in speed or increase the damping force as the piston approaches an end stop of the hydraulic cylinder to minimize variations in the damping force.
4 more elements
A method for controlling the damping of a heave compensator, wherein the method comprises:
- moving a piston of a hydraulic cylinder in a housing of the hydraulic cylinder to damp relative motion between a first structure coupled to the piston and a second structure coupled to the housing, wherein the housing comprises a permanent magnet disposed in an interior of the housing, and the piston comprises an inductive coil disposed in the interior of the housing and which is inductively coupled with and moves relative to the magnet in response to the movement of the piston in the housing;
- placing a magnetic fluid management system (MFMS) of the heave compensator in an energy harvesting mode;
- generating electrical energy in the inductive coil by electromagnetic induction in response to the relative movement of the inductive coil and the magnet in the housing with the MFMS in the energy harvesting mode;
- reconfiguring the MFMS from the energy harvesting mode to a separate damping mode such that a flow of electrical energy to an electromagnetic coil in the piston is provided whereby variations in damping force applied to the first structure are minimized;
- in the damping mode, decreasing the damping force as the piston increases in speed or increasing the damping force as the piston approaches an end stop of the hydraulic cylinder to minimize variations in the damping force;
- and
- subjecting the magnetic fluid in fluid communication with the hydraulic cylinder to a magnetic field at a flow passage for restricting the flow of the magnetic fluid and to adjust the damping between the first structure and the second structure in response to altering the viscosity of the magnetic fluid by supplying the electromagnetic coil with electrical energy with the MFMS in the damping mode.
4 more elements
A system for damping motion between an off-shore oil rig and a drilling string, the system comprising:
- a damping system coupled between the off-shore oil rig and the drilling string for damping motion therebetween, the damping system comprising:
- a first hydraulic cylinder coupled between the off-shore oil rig and drilling string and having a first housing, a permanent magnet disposed within an interior of the first housing, and a first piston disposed within the interior of the first housing and moveable in the first housing to damp relative motion between the off-shore oil rig and the drilling string, wherein the first piston comprises an inductive coil inductively coupled to the permanent magnet whereby electrical energy is generated in the inductive coil by electromagnetic induction in response to movement of the first piston in the housing relative to the permanent magnet;
- a first hydraulic fluid in the first hydraulic cylinder, the first hydraulic fluid comprising a magnetic fluid;
- and
- a first valve in fluid communication with the magnetic fluid;
- wherein an electromagnet is configured to produce a magnetic field at the first valve to change the viscosity of the magnetic fluid to adjust the damping of the relative motion between the off-shore oil rig and the drilling string;
- a second hydraulic cylinder coupled between the off-shore oil rig and the drilling string in parallel with the damping system for damping motion between the off-shore oil rig and the drilling string, the second hydraulic cylinder configured to accept a second hydraulic fluid and having a second housing and a second piston disposed within an interior of the second housing and moveable in the second housing to damp relative motion between the off-shore oil rig and the drilling string;
- and
- a magnetic fluid management system (MFMS) in signal communication with the damping system, wherein the MFMS is configured to selectably reconfigure the damping system between a plurality of separate operational modes including a damping mode configured to selectively alter the viscosity of the hydraulic magnetic fluid as the piston strokes through the housing to minimize variations in damping force applied to the drilling string;
- wherein, in the damping mode, the MFMS is configured to decrease the damping force as at least one of the first piston or the second piston increases in speed or increase the damping force at the at least one of the first piston or the second piston approaches an end stop of the first hydraulic cylinder or the second hydraulic cylinder to minimize variations in the damping force.
7 more elements
Dependencies are inferred from the claim text.