Method to improve brake closing response time

Abstract

The method of improving the brake closing response time on an offshore reel, comprising providing a brake disk, providing a control valve with a pilot on each end, providing a reference signal on one end, providing a control signal on the other end, shifting to a position to supply operating pressure to release brakes from a brake disk when said control signal exceeds said reference signal and venting said operating signal when said control signal is less than said reference signal.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

N/A

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

N/A

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISK

N/A

BACKGROUND OF THE INVENTION

The field of this invention is that of umbilical reels which store and handle hose and/or electric and/or fiber optic control lines for deepwater offshore service. These reels typically pay out these lines, called umbilicals, and mechanics clamp the umbilical to a drilling riser or other pipe string being run to the seafloor. The actual weight of the umbilical is typically supported once it leaves the reel and in the water by the riser or pipe to which it is clamped. Typically these reel units have to be closely monitored to insure that excessive tension, which can destroy the umbilical, is not encountered as it is being deployed or in the event of unexpected movement of the riser or pipe to which it is clamped .

When the drilling riser or other pipe string is lowered, an operator will rotate the spool to allow umbilical to be paid off in accordance with the downward movement of the riser or pipe. In some cases, the motor can be left in the take up mode, and the umbilical simply be pulled off the spool against a relatively constant torque provided by the motor power.

When appropriate the brakes are set to stop the motion of the reel. The brakes are typically of a spring closed or “failsafe” design. Air pressure is used to provide a force against the springs to open or release the brakes. The air pressure is supplied from a control panel mounted locally on the reel or from a remote station.

When it is desired to set the brakes, the valve at the local or remote station is opened to vent the air pressure from the brakes, allowing them to close. In the case of remote panels, sometimes as much as 200′ from the reel, the length of the lines can cause a delay in the closing of the brakes of up to 12 seconds.

Quick dump valves have been added to the piping near the brakes, but have been of little benefit as the volume of air in the signal lines is of the same general volume as the volume of air in the brakes.

Hundreds of reels have been installed on offshore floating drilling system since approximately 1960. In this time numerous reels have been installed at long distances such as 200′ from the control panel. Response times for setting the brakes are frequently as long as 12 seconds, which is an extremely long time in emergency situations. Industry experts have simply accepted this delay as normal as they had no alternatives to improve the response time.

BRIEF SUMMARY OF THE INVENTION

The object of this invention is to provide a method for reducing the response time for closing brakes on offshore reels.

A second object of the present invention is to provide a method of providing predictable control of the response time for closing brakes in spite of temporary reductions in the supply pressure.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. no. 1 is a view of a reel of this invention on the deck of a deepwater floating vessel, showing the umbilical clamped to a drilling riser.

FIG. no. 2 is an end view of a reel without this invention.

FIG. no. 3 is an end view of a reel of this invention.

FIG. no. 4 is a schematic of the control circuit of this invention when the brakes are activated or opened using a regulated supply to provide the operating pressure.

FIG. no. 5 is a schematic of the control circuit as in FIG. 4 when the brakes are deactivated or closed.

FIG. no. 6 is a schematic of the control circuit of this invention when the brakes are activated or opened using an unregulated supply to provide the operating pressure.

FIG. no. 7 is a schematic of the control circuit as in FIG. 6 when the brakes are deactivated or closed.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a vessel 1 floating on the ocean 3 and having a drilling riser 5 extending down toward a blowout preventer stack 7. The blowout preventer stack 7 is landed on a subsea wellhead 9 which is in turn landed on the seafloor 10. Casing 12 extends into the seafloor below the subsea wellhead 9 for the purpose of drilling an oil or gas well.

Reel 14 is positioned on the deck 16 of vessel 1 with umbilical 18 extending over pulley or sheave 20 and going down the side of the riser 5. Riser 5 is a series of jointed pipes and as they are sequentially connected and lowered into the ocean to lower the blowout preventer stack 7, clamps 22 secure the umbilical 18 to the drilling riser 5. The riser 5 and blowout preventer stack 7 may weigh as much as 650,000 lbs. When lowered with the umbilical 18 attached, if the rotation of the reel 14 is stopped, the full 650,000 lb. load can be put on the umbilical 18, destroying it. An even worse consequence is that the pulley or sheave 20 can be pulled down from its mounting and injure personnel on the deck 16.

Referring now to FIG. 2, reel 14 is shown with a frame 30 and a spool 32. Main disk 34 is shown mounted to the spool 32 by four slip clutch assemblies 36. As will be seen later, the slip clutch assemblies 36 provide a preset friction grip on the brake disk 34 to withstand torque as the spool 32 rotates, but will be allowed to slip if the preset friction grip is exceeded when a large tension on the umbilical 18 is encountered. A slip torque controller 37 is located on the side of the spool 32 which automatically adjusts the control pressure to the slip clutch assemblies 36 as the spool 32 rotates allowing the friction grip on the brake disk 34 to vary to maintain a relatively constant slip tension on the umbilical 18 as successive layers of umbilical 18 leave the reel 14 at different distances from the spool 32 centerline.

Motor 38 is shown with gear 40 (shown through the motor for clarity) engaging the outer gear profile 42 on the perimeter of brake disk 34. Gear 40 and the outer gear profile 42 are positively engaged such that if the motor 38 does not turn, the brake disk 34 cannot rotate. Alternately, the connection between the motor 38 and the brake disk 34 can be by roller chain and sprocket profiles, as is well understood in the industry. A motor torque controller 43 is located next to the motor 38 which adjusts the air pressure to the motor 38 as the spool 32 rotates to maintain a relatively constant tension on the umbilical 18 as the umbilical 18 leaves the reel 14.

Brake assemblies 44 and 46 are caliper or disk brake assemblies which are spring loaded to engage when air pressure is released. If the air pressure is released from these brakes, the brakes will close and the brake disk 34 will not rotate about the centerline of spool 32.

Spool 32 rotates on main bearings 48. Panels 50, 52, and 54 provide valves for remote control functions at the end of the umbilical. Levelwind 56, as will be seen in FIG. 3, has gear 58 to receive motive power from the brake disk 34 and a manual clutch and handle 59 which allows for adjustment of the wrapping position of the umbilical 18.

Locking pin 60 is engaged in locking pin socket 61 which is fixed to leg 62 of the reel frame 30. Locking pockets 63 are provided on the side of spool 32 for engaging locking pin 60 to positively stop the rotation of the spool 32. When locking pin 60 is an instrumented load pin, it can be engaged and give a positive reading of the torque output of the motor 38.

The air actuators 70 and 72 of brake assemblies 44 and 46 are connected by hose sections 74 and 76 respectively, which are in turn connected by hose 78 to control panel 80. Brake valve 82 on control panel 80 send an air pressure signal to push against a spring to release the brakes 44 and 46 from the brake disk 34. When the air is vented by brake valve 82, springs within the brake 44 and 46 cause the brakes to lock onto the brake disk 34 as air pressure is lost.

In control lines such as 78 of approximately 200′, the time it requires to vent this pressure and allow the brake assemblies to lock onto the brake disk is as much as 12 seconds. This is a long time for setting the brakes, especially on emergency situations.

Referring now to FIG. 3, a pressure brake assist (PBA) valve package 100 is shown installed in the line between the brakes 44 and 46 and the remote control panel 80. Line 102 is an air supply line which is used to power the control valve within valve package 100. Line section 104 is the new link between the valve package 100 and lines 74 and 76.

Referring now to FIG. 4, a pneumatic schematic of valve package 100 is shown with attaching lines as indicated in FIG. 3. Control valve 110 receives the control pressure signal from line 78 onto and air pilot 112 and at the valve inlet at 114. The pressure in signal line 78 will vary from zero to full rig air pressure at about 120 p.s.i. Full rig air pressure comes in line 102, goes through check valve 116, through regulator 118, and to air pilot 122 as a reference pressure. Pressure gauges are shown at 124 and 126.

The reference pressure going to air pilot 122 can be set to various pressures, however, testing has indicated about 80 p.s.i. is an optimum pressure. As is shown in FIG. 4, the control pressure in line 78 is increased to full rig air pressure of about 120 p.s.i. and the valve is shifted to the position as shown delivering the 120 p.s.i. to the brake actuators at 70 and 72. When regulator 128 is installed the control pressure in line 78 can be regulated to give an operating pressure to lines 114, 104, 74, and 76 and to the brake actuators if desired.

Referring now to FIG. 5, if the control pressure in line 78 is reduced to any pressure below 80 p.s.i. (the reference pressure) the valve shifts to connect line 104 to the vent port 112. This immediately dumps the pressure in line 78 to the atmosphere. When line 78 is approximately 200′ long as discussed in FIG. 2, the closing time for the brakes is reduced to approximately 3 seconds, or four times faster than the lines without the valve package 100.

Although the pressure from the brakes goes to zero quickly thru the valve package 100, the air pressure in the line 78 still declines over a 12 second period as before. Fully shifting valve 110 when the pressure in pilot 122 exceeds the pressure in pilot 112 substantially increases the safety of the unit by reducing the brake response time.

Referring now to FIG. 6, the connection on control valve 110 is moved to the unregulated supply upstream of regulator 118. In this position, the control pressure on pilot 112 can be regulated and the actuating pressure to operate the brakes will be either 0 p.s.i. or full supply air pressure.

The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention. Accordingly, the protection sought herein is as set forth in the claims below.

Claims

1. The method of improved the brake closing response time on an offshore reel, comprising

providing a brake disk,

providing a valve having a first position for delivering an operating signal to a release one or more brakes from engagement with said brake disk and a second position venting said operating signal to allow said one or more brakes to be engaged with said brake disk for stopping the rotation of said reel,

providing a first air pilot to move said valve to said first position and providing a second air pilot to move said valve to said second position,

delivering a reference air pressure to said second air pilot which is greater than zero but less that the air supply pressure,

increasing the control pressure delivered to said first pilot to a level greater than said reference pressure to shift said valve from said second position to said first position to cause said one or more brakes to be released, and

decreasing the control pressure delivered to said first pilot to a level lower than said reference pressure to shift said valve from said first position to said second position to deliver said operating pressure to allow said one or more brakes to be engaged with said brake disk.

2. The method of claim 1, further comprising providing a pressure regulator to adjust said reference pressure.

3. The method of claim 2, further comprising said operating signal is the same air supply pressure as is delivered to said pressure regulator.

4. The method of claim 1, further comprising said operating signal is the control pressure which is delivered to said first pilot.

5. The method of claim 1, further comprising said control pressure is regulated by a pressure regulator.

6. The method of claim 6, further comprising said operating signal is the control pressure which is delivered to said first pilot and is therefore a regulated air pressure.

7. The method of claim 1, further providing a check valve between said reference pressure and said air supply such that if said air supply is temporarily reduced, said reference pressure will not be affected.

8. The method of claim 1, further comprising providing a check valve between said air supply and said control signal such that if said air supply is temporarily reduced, said control pressure will not be affected.