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Patent Searching and Data


Title:
AN INTEGRATED OFFSHORE SAFETY SYSTEM
Document Type and Number:
WIPO Patent Application WO/1990/004700
Kind Code:
A1
Abstract:
This invention relates to an integrated offshore safety system on a buoy or like structure at a safe remote distance from the platform continuously monitoring safety data. Able to adopt primary or secondary control, receive, select and switch power. A remote subsea pump system supplies fire and deluge water and trickle charged hydraulic accumulators which actuate remote subsea emergency shut-off valves. A safety or service vessel can couple to the remote buoy/safety station to provide power or manual intervention and so allow re-entry to the platform by rescue and fire fighting crews.

Inventors:
BALL STANLEY (GB)
Application Number:
PCT/GB1989/001291
Publication Date:
May 03, 1990
Filing Date:
October 30, 1989
Export Citation:
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Assignee:
BALL STANLEY (GB)
International Classes:
B63C11/52; E21B35/00; (IPC1-7): E21B35/00
Foreign References:
GB1592972A1981-07-15
GB2085727A1982-05-06
US4619111A1986-10-28
GB949654A1964-02-19
US4192383A1980-03-11
Other References:
Oil & Gas Journal, Vol. 75, No. 42, 10 October 1977 (Tulsa, US) R. SMITH et al.: "Design Reliability into Offshore Shutdown Systems", pages 121-127
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Claims:
CT.RTM.
1. An offshore integrated safety system situated a safe remote distance from an offshore platform and being capable of the remote control of safety, emergency and shutdown situations.
2. 2. An offshore integrated safety system as claimed in Claim 1 wherein there is provided a fire protected umbilical subsea cable which can transmit power and data to or from the safety station.
3. 3. An offshore integrated safety system as claimed in Claim 1 and Claim 2 wherein there is provided a cable and connector to allow power and data connection to a rescue or service vessel. . An offshore integrated safety system, as claimed 210 in any preceding claim wherein a power generating and control unit is carried on a rescue or service vessel and connected to the safety station.
4. 5 An offshore integrated safety system as claimed in any preceding claim wherein the power supply and data can be selected from either the offshore installation, safety station or support vessel.
5. 6 An offshore integrated safety system as claimed in any of the preceding claims wherein a remote subsea fire and deluge water pump is powered and controlled by an umbilical cable from the safety station.
6. 7 An offshore integrated safety system as claimed in any preceding claims wherein subsea flowline SUBSTITUTE SHEET valves are powered and controlled by an umbilical 225 cable from the safety station.
7. 8 An integrated offshore safety system as claimed in any of the preceding claims wherein the safety station is part of a shared facility such as, but not restricted to, a flare, location buoy, loading buoy or other offshore installation.
8. 9 An offshore integrated safety system as claimed in any preceding claim wherein a fire and deluge water pump system as described is easily installed/removed from a subsea base without the need for diver assistance.
9. 10 An offshore integrated safety system as claimed in any preceding claim wherein the pump as described is located at a distance to avoid diver problems, and in which the power switching and control may be some greater distance away on a remote safety installation.
10. 11 An offshore integrated safety system as claimed in any preceding claim wherein the pump and motor subsea assembly as described is used in whole or in part for the pumping of fluid other than seawater.
11. 12 An offshore integrated safety system as claimed in any preceding claim wherein subsea emergency shutdown valves are actuated from hydraulic accumulators which have been hydraulically trickle charged by small hydraulic motors supplied by small capacity cables giving power and control from a remote safety station. The accumulators when charged being capable of giving a number of SUBSTITUTE SHEET actuations to each valve .
12. 13 An offshore integrated safety system substantially as hereinbefore described with reference to the accompanying drawings . SUBSTITUTE SHEET.
Description:
AN INTEGRATED OFFSHORE SAFETY SYSTEM

This invention relates to an offshore safety system in which data collection, power supply and switching of a subsea remote fire/deluge pump and the actuation of remote subsea emergency shutdown valves is obtained and controlled by a computer in a safety station.

It would continuously monitor, record and compute safety data. Adopt primary or secondary control of safety systems and emergency power. In emergency or abandonment the safety station would provide fire and deluge water, emergency power, control of safety systems, shutdown of subsea flowline valves, a lifeboat tether and survival post. Some installations would include an absail escape wire system. Connectors on the safety station would allow intervention by rescue or service vessels.

Offshore installations such as platforms, production units, drilling units, and the like are hereinafter referred to under the general terms of offshore platforms.

Such offshore platforms normally have sophisticated safety systems, controlled by a control room. Sometimes they also have a secondary control point.

However, all such safety systems have their power

SUBSTITUTE SHEET

supply and control on the platform itself.

During diving operations it has been the practice and regulation to take the fire and deluge water pumps off the automatic control.

Gas and oil escapes can be caused by drilling, riser fracture, malfunction or collision of a vessel with the platform.

Many installations have incoming and outgoing oil and gas flow lines. The only immediate means of shutting off the flow lines are by valves on the platform itself.

The inability to close off flow lines has meant large volumes of oil and gas have been available to feed uncontrollable fires.

Fires under platforms have on occasions made it impossible to launch lifeboats or for personnel to escape from the platforms.

In the past, fire, deluge and other safety systems have been delayed or prevented from operation by diving activities, control room maintenance, damage, inacceεsability or abandonment.

After abandonment of an offshore installation it has not been possible for rescue parties to operate and control the safety systems.

-SU3ST-TUTE SHEET

According to the present invention there is provided a safety station situated a safe remote distance from an offshore platform .able to continuously monitor, record and compute safety data. Adopt primary or secondary control of safety systems and emergency power. In emergency or abandonment the safety station would provide fire and deluge water for a subsea unit, emergency power, control of safety systems, shutdown of subsea flow line valves, provide a lifeboat tether and survival post. Some installations would include an absail escape wire system.

Connectors on the safety station would allow intervention to the platform by rescue or service vessels.

Under normal daily routine the safety station would receive power from the offshore platforms via an umbilical cable to provide general service power and battery charging on the safety station. Along the same umbilical cable would be transmitted safety system data. This would be referenced by the computer and any appropriate action taken.

Power and data from the safety station would be supplied to subsea valves to ensure the actuators are always fully charged.

In emergency the safety station would transmit power

SUBSTITUTE SHEET

and data to subsea valves, remote subsea fire and deluge water pumps, also back to the offshore platform 75 for operation of the various other systems.

The size of the safety station would depend on economics.

A large safety station would have a fire protected umbilical connection from the offshore platform plus 80 its own large and small power generators; additionally it would have a connector to allow for power supply and system control from a rescue or service vessel.

Computer controlled switch gear would select the most appropriate power supply.

85 In shallow water the structure would be a fixed tower. In deep water it would be a tethered buoy.

Although unmanned there would be space for maintenance personnel, survivors and a medi-centre.

When economics dictate a small safety station, it would 90 be a tethered buoy but without a large power generator.

In the past remote buoys have been suggested for the- supply of fire/deluge water from pumps attached to the platform or buoy structure and conducted by continuous pipeline between buoy and platform, or supply of 95 firewater from a vessel stabbed into a pipe riser at the surface. A fire pump power supply on a vessel to

-SUBSTITUTE SHEET

operate the platforms own pumps has also been suggested.

A specific embodiment of the invention will now be 100 described by way of example with reference to the accompanying drawings in which:-

Fig 1 is a diagramatic view of a safety station system Fig 2 is a drawing of the remote subsea fire and deluge water pump system.

105 Referring to Fig 1, a typical offshore installation 1 needs additional safety cover as provided by a safety station. A typical large safety station is shown at 2, or an alternative typical small safety station as shown at 3.

110 Routine daily power and communication is by umbilical cable 4, to avoid scouring by sea motion of the cable the weight is taken on submerged support 5. Safety station 2 is secured in position by anchor 6, anchor cables 7 are tensioned by a procedure using anchor

115 handling tugs (not shown) and secured to 8.

Alternative power supply can be from the safety station generators (not shown) or from a rescue/service vessel 9, via connector 10. The selected power and data are transmitted to the subsea fire and deluge pump 11 via 20 umbilical cable 12. Fire and deluge water is pumped through the subsea pipeline 13 and up the riser pipe 14 to a non return valve 15 and then into the

SUBSTITUTE SHEET

installation's own fire and deluge systems shown dotted 16.

125 Routine power and data for the charging of subsea flow line valve actuators 17 are transmitted on umbilical cables 18.

In the case of evacuation/abandonment of the offshore installation 1 the safety station has arc lights 19, to 130 illuminate the surrounding sea. Lifeboats can group and tether at 20.

Survivor and medi centre space 21 on safety station 1 is for short term use.

Helicopter pad 22 is used for maintenance crew or - 135 survivor lift-off using helicopter 23.

Intervention by rescue or service vessel would use connection 10.

Platform evacuation is assisted by absail escape wire 24.

140 Fig 2. The subsea pump and motor assembly (25) is easily installed or recovered by a surface vessel without the need for diver assistance.

The pump and motor assembly (25) comprises a pump (26) a submersible motor (27) fitted on a fabricated pallet

145 (28) which has a tubular frame (29) which acts as a

SUBSTITUTE SHEET

protector and has lifting lugs (30).

The sides and top of the tubular frame are boxed in with panels (31) to form an enclosure. The panels on the long sides have high level inlet grills (32) for 150 seawater entry.

The seawater is sucked into a shaped duct (33) so the fast flowing water cools the motor (27) and then enters the pump throuogh a fine mesh filtered inlet (35). if 155 a liquid other than seawater is required then an inlet and coupling will be provided (34 not shown). A small ancillary pump can be fitted to assist cooling if required (not shown).

The outlet from the pump has a remote actuated 160 coupling.

The subsea pump and motor assembly (25) is easily installed/removed from a permanently installed subsea base (37) which has a mud mat (38) and an optional erosion mat (not shown) .

165 The base is secured to the seabed by piles (39) which are held in pile guides (40) cradles and clamps form an anchor (41) to hold the subsea pipeline (42) in a fixed position.

A positioner (43) keeps a space between the coupling 170 and pipe end during installation.

SUBSTITUTE SHEET

Locators (44) on the base (37) positively locate and lock the pump and motor assembly (25) .

For installation a lift and guide frame (45) is secured to the lifting lugs (30) on the pump and motor assembly 175 (25) by hydraulic lock and release units (46). Guide wires are secured to the installation vessel (48) and the bottom ends are attached to the locators (44). gates in the cone guides allow the lift and guide frame to be slotted onto the guide wires (47).

180 When the pump and motor assembly (25) is positively locked onto the seabed base (37) an hydraulic system (49) closes and locks the remote actuated coupling (36).

The lifting and guide frame (45) and guide wires (47) 185 are removed to the surface.

Emergency subsea shut-off valves (17) are connected to the safety station by small combined power and data cables (18) data is received from the platform via cable (4) and the subsea emergency shutdown valves by 190 cable (18). In this patent it is only necessary to have small power cables (18) to operate small hydraulic pumps (50) which trickle charge hydraulic accumulators (51) capable of giving a minimum of three actuations of each valve.

195 The safety station analyses data and instigates action.

SUBSTITUTE SHEET