SHERIFFDOM OF GRAMPIAN, HIGHLAND AND ISLANDS AT ABERDEEN

FATAL ACCIDENTS AND SUDDEN

DEATHS INQUIRY (SCOTLAND) ACT 1976

INQUIRY INTO THE DEATHS OF

SEAN SCOTT McCUE and KEITH SCOT MONCRIEFF

DETERMINATION BY THE SHERIFF

1. INTRODUCTION

This is an inquiry under the Fatal Accidents and Sudden Deaths Inquiry (Scotland) Act 1976 into the deaths on 11^th September 2003 of Sean Scott McCue and Keith Scot Moncrieff on board the Brent Bravo Offshore Platform situated in the United Kingdom sector of the North Sea. While Mr McCue and Mr Moncrieff were working at the 81 metre level within the utility shaft there was a release of liquid hydrocarbons from a temporary repair on the closed drain degasser rundown line. The released liquid evaporated forming vapour in the shaft and as a direct consequence of inhalation by the two men of the vapour, they died.

On 1 August, 2005 the Sheriff at Aberdeen, on the application of the Procurator Fiscal for the District of Aberdeen, made an order appointing the inquiry to commence on 31 October, 2005.

The scope of a fatal accident inquiry is limited by the terms of section 6 of the 1976 Act, which requires the Sheriff to:-

"make a determination setting out the following circumstances of the death so far as they have been established to his satisfaction:-

(a) where and when the death and any accident resulting in the death took place;

(b) the cause or causes of such death and any accident resulting in the death;

(c) the reasonable precautions, if any, whereby the death and any accident resulting in the death might have been avoided;

(d) the defects, if any, in a system of working which contributed to the death or any accident resulting in the death; and

(e) any other facts which are relevant to the circumstances of the death."

At the inquiry the Procurator Fiscal who appeared and adduced evidence regarding the circumstances of the deaths was Ernest Barbour, Esq. Also appearing were Stuart Gale, Esq, Queen's Counsel, who represented Shell U.K. Limited and adduced evidence on their behalf; Peter Gray, Esq, Queen's Counsel, who represented the Wood Group; Christine McCrossan, Solicitor, representing the interests of Jackie Ogilvy, the partner of the late Keith Moncrieff; Gary McAteer, Esq, Solicitor, who acted on behalf of two Offshore Installation Managers, namely Terry Stout and John McEwan, and who led evidence on their behalf; and David Sheldon, Esq, Advocate, who represented the Health and Safety Executive.

The inquiry sat on 38 days during which the evidence of 61 witnesses was taken, either orally or by way of affidavit and, following submissions on behalf of each of the parties represented at the inquiry, concluded on 25 January, 2006.

During the course of the inquiry it became apparent that evidence relating to the condition of certain valves on the platform might be relevant to the cause of the deaths of the two men, or have contributed to the incident which resulted in their deaths. However certain evidence, such as the possible consequences to the structure of the platform, and its crew, of the ignition of the vapour within the utility shaft, while of concern to some of the parties and no doubt of importance to the offshore oil industry and those who work in it, was, in my opinion, beyond the scope of the 1976 Act and more appropriate for consideration at an inquiry of a more general nature.

2. THE WITNESSES

(a) The witnesses who appeared and gave oral evidence.

1. KENNETH THOMSON (41) - a photographer employed by Grampian Police who, on 13 September, 2003, took a series of photographs, and a video, at the 81 metre level within the utility shaft of the Brent Bravo platform.

2. THOMAS WOTHERSPOON (47) - a maintenance scheduler employed by the Wood Group on the Brent Bravo platform who, on or about 17 November, 2002 in his capacity as mechanical lead technician, placed patch No. 86 on the closed drain degasser rundown line located within the utility shaft of the Brent Bravo platform.

3. IAN ALEXANDER SILK (41) - a logistics manager employed by Shell U.K. Limited who presented, by text and graphics, a general description of the Brent Bravo platform, the utility shaft, the relevant work area and its location, a brief introduction to the function of the main equipment and pipework systems within the utility shaft.

4. PAUL WILLIAM ADIE (35) - an operations technician employed by Shell U.K. Limited, who, on 11 September, 2003, was the control room operator on the Brent Bravo platform.

5. SYDNEY CECIL THOMSON (38) - a systems supervisor, process (S.S.P.) employed by Shell U.K. Limited on the Brent Bravo platform, who, on 11 September, 2003 was acting operations supervisor.

6. PETER LAYCOCK (45) - an electrical technician employed by the Wood Group on the Brent Bravo platform who, on 11 September, 2003 prior to 3.30 pm, while in the technicians station locker room was asked by Keith Moncrieff if there was any rubber in the switch room.

7. STEPHEN ALAN DEETH (26) - an operations technician employed by Shell U.K. Limited on the Brent Bravo platform and who, on 11 September, 2003 was a trainee involved in preparations for a pig launch.

8. ALISTAIR STUART HARCOMBE (38) - an operations technician employed by Shell U.K. Limited on the Brent Bravo platform who, during the annual shutdown in August, 2003 investigated with Scott Fraser a single gas head low level alarm at the 81 metre level in the utility shaft.

9. CLARK ANDERSON (27) - a productions operator who was employed by Shell U.K. Limited on the Brent Bravo platform and had during the shutdown in August, 2003 investigated with Paul Buchan a gas alarm at the 81 metre level in the utility shaft and had on or about 9 September, 2003 together with Alistair Harcombe checked Patch No. 86.

10. PAUL ARTHUR BUCHAN (28) - an operations technician employed by Shell U.K. Limited on the Brent Bravo platform who, a few months prior to the annual shutdown in August, 2003, looked at, and assessed the condition of Patch No. 86. On 11 September, 2003 he was involved in preparations for a pig launch.

11. JOHN DELANEY CAIRNEY (43) - an installation inspection engineer presently employed by the Salamis Group who was employed by Motherwell Bridge Inspection and has worked, from about 1997 on the Brent Bravo platform. He kept the patch register and monitored all temporary repairs during his monthly inspection.

12. TREVOR CHRISTOPHER ANCELL (51) - a chartered mechanical engineer who, in September, 2003 was employed by Shell U.K. Limited on shore as the principal technical authority (piping and static equipment), for all the Shell Expro installations including the Brent Bravo platform.

13. TERRY WILLIAM ANDERSON STOUT (38) - an offshore installation manager employed by Shell U.K. Limited who, on 11 September, 2003 was an operations supervisor but was acting as installation manager on the Brent Bravo platform.

14. MARK GALLAGHER (45) - a mechanical technician employed on the Brent Bravo platform by the Wood Group who, on 11 September, 2003 was asked by Keith Moncrieff if he would go down the utility shaft and replace a patch on a pipe.

15. DR ROBERT STRACHAN STEPHEN (56) - a doctor employed by Shell U.K. Limited who, in 2003 was based on the North Cormorant installation and attended the Brent Bravo platform on 11 September, 2003 and at about 19:55 pronounced Sean McCue and Keith Moncrieff dead.

16. DAVID ANTHONY CHAPMAN (51) - an operations technician employed by Shell U.K. Limited who on 11 September, 2003 was the responsible person electrical on the Brent Bravo platform and who, during the general platform alarm and emergency shutdown was dispatched to check, and manually start, the emergency generator, which had not started automatically, in order to restore lighting.

17. THOMAS MURPHY STELMACH (48) - an offshore medic employed by Universal Sodexho on behalf of Shell U.K. Limited and based on the Brent Bravo platform who on 11 September, 2003 at about 7.00 pm descended the utility shaft together with Iain Ayers and Billy Boyse and found Sean McCue and Keith Moncrieff lying at the 81 metre level.

18. GEOFFREY TALBOT (52) - an inspection team leader employed by Shell U.K. Limited for the central asset unit and who is based onshore.

19. FRANK MILLAR (56) - a shutdown co-ordinator employed by Wood Group Engineering (North Sea) Limited who was the integrated services contract team leader on 11 September, 2003 on the Brent Bravo platform and who, on 9 September, 2003 instructed Keith Moncrieff to contact the area technician and together they should look at Patch No. 86, which reportedly was leaking, and assess its condition and report back to him.

20. ANNE WILSON HART (41) - employed by Shell U.K. Limited onshore as the engineering and maintenance leader for the central asset and who as maintenance team leader was responsible in September, 2003 for the Brent Bravo platform. One of her teams was responsible for arranging the design and fabrication of replacement pipe spools.

21. CHRISTOPHER JAMES GRANT (31) - a campaign maintenance co-ordinator employed by Shell U.K. Limited at their Tullos office in Aberdeen who was, on 11 September, 2003 acting systems supervisor, process (S.S.P.) on the Brent Bravo platform.

22. JAMES ALEXANDER SMITH (37) - a pipeline engineer employed by Shell U.K. Limited who during the general platform alarm and emergency shutdown assisted Paul Buchan to attach a hose to the closed drain system in order to put water down the line and thereafter assisted Dave Chapman to start the emergency generator.

23. STEPHEN JOHN CLAYTON (54) - a senior control and automation engineer employed by Shell U.K. Limited at their Tullos office in Aberdeen as part of the technical authority.

24. WILLIAM JOHN BOYSE (39) - who in September, 2003 was employed by the Wood Group on the Brent Bravo platform as an instrument technician. On 11 September, 2003 was told by Keith Moncrieff that he was going down the utility shaft that day to change a bit of rubber and a couple of jubilee clips.

25. JOHN JAMES MACASKILL (26) - an electrical technician employed by the Wood Group on the Brent Bravo platform and who, on 11 September, 2003 was an apprentice and heard Keith Moncrieff, at the 3.00 pm tea break, ask Peter Laycock if he had any rubber.

26. IAIN AYERS (43) - an instrument technician employed by the Wood Group who, on 11 September 2003, while on board the Brent Bravo platform was asked by Keith Moncrieff, at the 3.00 pm teak break, to lend him a screwdriver, which he did.

27. SCOTT FRASER (37) - an operations technician employed by Shell U.K. Limited on the Brent Bravo platform who, on 17 August, 2003 together with Alistair Harcombe investigated a single gas head low level alarm at the 81 metre level in the utility shaft and whose role on 11 September, 2003 was technical custodian instruments.

28. JONATHAN ROBERT STATHAM (40) - a senior scientist employed by the Health and Safety Executive at their laboratory in Buxton, Derbyshire, who together with Christopher Parker and Dr Roy Parrott carried out tests on a number of items and prepared a report thereon.

29. CHRISTOPHER JOHN PARKER (31) - a scientific officer employed by the Health and Safety Executive at their laboratory in Buxton.

30. DR ROY PETER PARROTT (56) - a senior materials scientist employed by the Health and Safety Executive at their laboratory in Buxton.

31. RAVINDER KUMAR SHARMA (54) - a chartered mechanical engineer employed by the Health and Safety Executive as a specialist inspector who carried out an investigation into, and prepared a technical report on, the fitness for purpose of Patch No. 86, the condition of the non-return valve 9P097, the emergency shut-off valve EZV 44715 (including the actuator) and the level control valve 6600.

32. DR BERNARD EMERY (61) - an operations inspector employed by the Health and Safety Executive who specialises in control instrumentation and electrical engineering and investigated the gas detection systems used on board the Brent Bravo platform and who prepared a report thereon.

33. DAVID MICHAEL HARRIS (48) - an operations supervisor employed by Shell U.K. Limited on the Brent Bravo platform who in July, 2003 assisted Norman Lloyd to review outstanding work orders including 10449718.

34. JOHN ROBERT McEWAN (57) - an offshore installation manager employed by Shell U.K. Limited on board the Brent Bravo platform who was the O.I.M. on board when the platform started up on 22 August, 2003 following the annual shutdown.

35. MARTIN ALAN BREARLEY (57) - an inspector employed by the Health and Safety Executive specialising in fire and explosions who, together with Dr Venessa Forbes and V Karthigeyan, prepared a report on the potential consequences of ignition of the gas release in the utility shaft of the Brent Bravo platform.

36. PROF. GEOFFREY ALAN CHAMBERLAIN (57) - the manager of the major hazards management team within the health, safety and environment department of Shell Global Solutions who prepared the report "Brent Bravo Incident: Summary of the Dispersion and Explosion Analyses Performed by Shell Global Solutions".

37. V. KARTHIGEYAN (57) - an inspector with the Health and Safety Executive specialising in structural integrity of concrete, structural dynamics, earthquake engineering and vessel impact who co-authored the technical report on the potential consequences of ignition of the gas release in the Brent Bravo utility shaft.

38. DR. VENESSA JANE FORBES (35) - an inspector with the Health and Safety Executive specialising in structural integrity who was the report co-ordinator for the technical report on the potential consequences of ignition of the gas release in the Brent Bravo utility shaft.

39. ROBERT JOHN WHITE (46) - a principal inspector employed by the Health and Safety Executive specialising in structural integrity who prepared an addendum and update to the technical report on the potential consequences of ignition of the gas release in the Brent Bravo utility shaft.

40. TREVOR HODGSON (50) - a chartered engineering who acts as a chief consultant for Galbraith Consulting Limited and who prepared a report entitled "Explosion Loading in Utility Shaft".

41. ROBERT ERNEST GOWERS (52) - a specialist inspector employed by the Health and Safety Executive in their offshore safety division who, between 13 September, 2003 and 16 September, 2003 carried out an investigation on board the Brent Bravo platform into the incident on 11 September, 2003 and produced a report thereon.

42. DR JAMES HENDERSON KERR GREIVE (52) - a fellow of the Royal College of Pathologists employed in the Forensic Medicine Unit of the Department of Pathology at the University of Aberdeen who on 15 September, 2003 together with Dr Sameena Rashid carried out, and thereafter prepared a report on, the post-mortem examinations of Sean McCue and Keith Moncrieff.

43. DR VALERIE FLOOK (65) - a chartered physicist who is the principal of a company Unimed Scientific Limited and prepared a report dated 27 February, 2004 into the likely cause of death of Sean McCue and Keith Moncrieff.

44. ANILKUMAR CHOHAN (52) - a relief operations supervisor employed by Shell U.K. Limited and who was on board the Brent Bravo platform from 20 August, 2003 and was on board when the platform started up following the annual shutdown.

45. NORMAN LLOYD (56) - an electrical engineer employed by the Wood Group who, as integrated services team leader (I.S.C. team leader) in the Brent Field carried out with David Harris a review of outstanding work orders and cancelled work order 10449718 relating to the emergency shut-off valve EZV 44715.

46. DAVID RICHARD BEAN (59) - a mechanical technician employed by the Wood Group on board the Brent Bravo platform who worked on the emergency shut-off valve EZV 44715 during the annual shut down in 2002 and reported to his mechanical supervisor Peter O'Brien.

47. GEORGE ALEXANDER LANG (55) - employed by Shell U.K. Limited as the engineering and maintenance team leader for their cross border asset who in September, 2003 was based onshore as the asset leader for the four platforms in the Brent field.

48. RAYMOND WILLIAM PATERSON (59) - an inspector employed by the Health and Safety Executive who was a member of the team that went on board the Brent Bravo platform to investigate the incident which occurred on 11 September, 2003 and took a number of photographs with Phil Mullery and was party to the issuing of prohibition notices.

49. MARJORIE CHAMBERLAIN (33) - employed by Shell U.K. Limited as head of design for the Brent project group who in 2003 provided onshore mechanical maintenance support for the Brent asset and in August, 2003 considered the patch register and on 4 September, 2003 requested a new spool for 2"D-115-A1105 from the maintenance delivery team.

50. ROBERT MILLER NICOLL (53) - a senior control and automation engineer employed by Shell U.K. Limited who is the technical authority for their mature assets group.

51. JOHN CARDWELL (49) - an off-shore installation manager employed by Shell U.K. Limited who took timings, or caused timings to be taken relating to the time taken to descend from the DICS to the 81 metre level in the utility shaft.

52. JENNIFER TALBOT (28) - employed by Shell U.K. Limited as a styles and procedures co-ordinator at their Tullos office in Aberdeen who in 2004 drafted the operating code of practice (OCOP) document for leg entry.

53. JOHN HOLROYD (56) - an inspection team leader employed by Shell U.K. Limited who is in charge of the inspection and corrosion engineers within the Brent asset.

54. COLIN DAVID LEIGHTON (44) - a chartered mechanical engineer employed by Shell U.K. Limited at their Tullos office in Aberdeen and who is involved in the performance standards assurance programme.

55. BRIAN ROBERT TWADDLE (42) - an employee of Shell U.K. Limited and the project manager of MACH (minicell and column hydrocarbon project).

56. JOSEPH PRIEST (52) - a non-destructive tester on the Brent Bravo platform who was employed, in September 2003 by Motherwell Bridge Inspection.

(b) The witnesses who provided affidavits

57. JANICE FLINT - a personnel manager employed by Wood Group Engineering (North Sea) Limited who gave evidence relating to Keith Moncrieff's employment with the Group.

58. JOHN ARMSTRONG - a radio operator admin. employed by Universal Sodexho who was on board Brent Bravo on 11 September, 2003 and informed, by radio, Shell Log and the offshore standby vessel Havila Star of the situation and also apprised, by telephone, the coast-guard in Aberdeen of the situation on Brent Bravo.

59. HUGH MUIRHEAD McCUE - the father of Sean McCue.

60. DERK KAPPELLE - a director of Shell U.K. Limited, the owners of the Brent Bravo Offshore Platform who spoke to the location of the platform in the North Sea.

61. SIMON DAVID REID - a chartered mechanical engineer employed by Bureau Veritas as a senior verification engineer and was in 2003 the verification focal point for the Brent Field verification.

3. THE BRENT BRAVO OFFSHORE PLATFORM

(a) General Description

The Brent Bravo platform is a concrete platform structure built to the Condeep design and installed in the Brent field complex in the mid 1970s. The complex comprises four production platforms, namely Alpha, Bravo, Charlie and Delta. The Brent field is located in Quadrant 211, Block 29 of the United Kingdom sector of the North Sea. The platform sits in about 140 metres of water.

The oil produced by the Brent field is exported, via the Cormorant A platform, to Sullum Voe. The produced gas is exported via the Brent system to St Fergus.

The topside and process facilities of the platform are supported by a concrete gravity structure sitting on the seabed and comprises of nineteen compartments, or cells, three of which extend upwards as legs, or shafts, in order to support the topside structure. The three legs measure some 170 metres in height.

Sixteen of the compartments provide a storage and settlement system for the produced oil and liquids and hold 159,000 m³ of oil and water.

The two southern legs contain production well conductors and are filled with water to sea level. These two legs are not normally accessed.

The northern leg, or utility shaft, contains pipework and pumps for the oil storage and export system. The water level in the utility shaft is normally maintained at about 74.5 metres above the leg base. A minicell is located at the base of the utility shaft and is normally flooded but can be dewatered.

The concrete structure requires to remain in compression for structural stability and the cells are maintained full of liquid with oil on top, water below, with a settlement interface. The structure is subject to constant pressure from the internal column of water and a header tank.

The upper section of the utility shaft contains piping systems and pumps for (i) sea water cooling (service water), (ii) five pumps, (iii) produced water and (iv) crude oil export. Oil lines in the utility shaft transport produced oil and water to the storage cells. There is a platform at the 157.4 metre level,, a platform at the 101.2 metre level which supports the drawdown header tank and a platform at the 96.2 metre level which supports the storage water pumps.

The mid section of the utility shaft controls the production storage and distribution. The oil rundown lines enter the 24 inch manifold situated on the 81.2 metre level which also supports the oil booster pumps. The crude oil export lines terminate at the 81.2 metre level. A platform at the 76.7 metre level supports the storage manifold and below this the cell fill lines distribute stored production to the surrounding concrete cells.

The lower section of the utility shaft, the bilge, is normally filled with water to 74 metres and is not accessed. It contains a central circular structure known as the minicell. The storage water is routed through the minicell and out to the base of the concrete cells. In addition to the functional storage water lines a number of redundant lines associated with the platform installation remain in place and were cement filled after the platform base was grouted to the seabed.

The utility shaft may be accessed either by means of the lift, which terminates at the 81.2 metre level, or by 90 metres of stairs.

(b) The Power Sources

(i) Three main generators, Avon gas turbines, supply all the systems on the platform and are designed to automatically switch off when there is a general platform alarm and shutdown.

(ii) The back-up power supply is by means of two diesel fuelled Ruston submain generators which are inhibited from starting if there is a gas release on the platform.

(iii) Thirdly, there is an emergency diesel generator, which on sensing there is no power automatically, within a minute, runs up and closes on to the switchboard in order to supply power for essential systems such as light, radios etc. The running of the emergency generator will depend on the gas situation on board the platform.

(iv) Finally, there is a system known as the uninterrupted power supply (U.P.S.) which operates on batteries in the event of loss of A.C. power on the platform, and supplies communications and other systems in order to facilitate the emergency response and the resumption of main power generation.

(c) The Utility Shaft

(i) Pipework

The identifiable pipework systems contained within the utility shaft are, firstly, the three 8 inch oil rundown lines which transfer crude oil from the platform process system to the concrete storage cells at the base of the platform. The oil rundown lines enter the 24 inch manifold independently and are fitted with isolation and level control valves.

Secondly, the storage manifold which is located at the 76.7 metre level and allows the flow from the oil rundown lines to be diverted to the selected cell storage system and individual cells. The storage manifold is also used to reverse the flow to the oil export lines.

Thirdly, the cell fill lines which route the flow from the utility shaft to selected external storage cells which are clustered around the three platform legs.

Fourthly, the oil export lines which allow, when required, the stored oil to be pumped to the export flowline.

Fifthly, the storage water lines which can be used to introduce water to, or draw water from, the cells so as to maintain the water levels within the storage cells.

Sixthly, an independent service water system which provides seawater for the required platform functions.

Seventhly, an independent fire water system which provides seawater for the platform fire and deluge systems.

Eighthly, the ballast lines which were designed for use during the installation operations and are now redundant and are grouted and isolated.

In addition to the three 8 inch oil rundown lines four other lines from services located on the platform topside, connect to the 24 inch manifold. Firstly, the redundant drain line from the Brent Alpha platform. Secondly, the closed drain line from the process drains degasser vessel located at the 158.2 metre level in the utility shaft. Connected to the closed drain degasser rundown line, by means of an equal 4 inch tee and a 6 inch by 4 inch reducer, is the open drain line from tanks located on the lower deck of the platform. Also connected to the closed drain degasser rundown line, with an isolation valve, is a line from the caisson pumps on the level below. The closed drain degasser rundown line is fitted with isolation valves, a level control valve and a non-return valve. Finally, the condensate line routed from the low pressure flare knock-out drum located on the south face of the platform connects to the 24 inch manifold but is split and enters the manifold at two points. Both branches of the condensate line are fitted with isolation valves and level control valves.

(ii) Gas and Fire Alarm Systems

Within the utility shaft is a fixed fire (both flame and smoke detection) system and a gas detection system.

There are twenty one fixed gas detectors placed throughout the utility shaft to identify situations where a gas hazard exists. There are six situated at the 76 metre level, including three in the heating, ventilation and air conditioning extract; three situated at the 81 metre level; three at the 96 metre level; three at the 101 metre level; and six situated at the 154 metre level. The gas detectors are arranged in voting groups. As pellistors are not infinitely reliable and in order to guard against a situation where one false indication could cause an emergency shutdown the gas detectors are arranged in groups of three so that at least two detectors require to sense gas before there is any executive action.

The devices intended for light gas fractions such as methane are calibrated to indicate 60% of the methane lower explosive limit with 2.5% methane, i.e. their sensitivity is set about 27% high in relation to methane and this allows for some deterioration in sensor performance. The lower explosive limit for methane is 5%.

Detectors intended for heavier gas fractions are calibrated to indicate 95% of the lower explosive limit with 2.5% methane. Accordingly, they indicate about twice the correct value if sensing methane but because pellistors are less sensitive to heavier fractions, their reading when sensing heavier fractions is lower and usually closer to a correct reading.

The calibration of gas detection heads is checked on a regular basis and was checked in July, 2003.

A gas reading of 20% of scale produces an alarm condition called "low gas" and a reading of 50% of scale is called "high gas". As the gas detectors in the same area are connected in voting blocks if two or more detectors in a given voting block register low gas this is a "confirmed low gas" condition. Similarly, if two or more detectors register high gas this is a "confirmed high gas" condition.

All gas alarm indications are available to the control room operator but a confirmed reading is required before any automatic executive action, such as a general platform alarm or shutdown, occurs.

The fire and gas system logs data which can be subsequently analysed.

(iii) C.C.T.V.

The various levels within the utility shaft can be monitored by the operations control room personnel by means of C.C.T.V. cameras. These cameras transmit black and white images to the operations control room. In September, 2003 the quality of the images was poor and lacked clarity, but were adequate to enable the personnel in the operations control room to locate on 11 September, 2003 the deceased lying at the 81 metre level within the utility shaft. One of the cameras sited at the 81 metre level did not, on 11 September, 2003 pan effectively.

(iv) Communications

On board the Brent Alpha platform there is a Tannoy public address system which allows information, and orders, to be announced throughout the platform, including the utility shaft. In addition, there is a telephone system with fixed telephones at each level within the shaft which enable two way communication between persons in the shaft and the operations control room.

(v) Emergency Lighting

Each emergency light fitting in the utility shaft has two fluorescent tubes which are powered by the emergency generator. In the event that the emergency generator does not start, emergency lighting in the utility shaft is powered by the batteries but only one tube in each emergency light fitting comes on thereby reducing the visibility in the shaft considerably.

(vi) Procedure in 2003 for entry to the Utility Shaft

The utility shaft of the Brent Bravo platform has a single point of access and egress and is thus subject to confined space safety procedures as though personnel were entering a vessel. Personnel who work in the shaft are all qualified as either leg competent or the higher qualification of leg authorised. In order to be leg competent an employee must have undergone training and be familiar with the position and function of the equipment within the shaft such as use of the lift, telephones, fire extinguishers, breathing apparatus and deluge sets in addition to being aware of the procedure in the event of an alarm and he must know his muster point. In order to qualify as leg authorised personnel, mostly Shell U.K. Limited technicians, must be trained in the processes which occur within the shaft in addition to being familiar with the requirements for leg competence. The names of those persons who are qualified as leg competent or leg authorised are entered onto the Authorised Persons Register together with the effective date of their authorisation and the date when that authorisation expires.

No person was permitted to enter the utility shaft alone or to work in the shaft alone, and only persons trained and competent in the use of breathing apparatus were allowed to enter the shaft. Unless there was breathing apparatus at every level in the leg, and in sufficient numbers for entry purposes, each person entering the shaft required to be issued with personal breathing apparatus.

The maximum number allowed to enter the utility shaft was determined and approved by the asset owner and each job in the shaft was assessed by the platform manager and the number of personnel involved in the task restricted accordingly.

At the point of entry to the utility shaft there was a notice board on which was displayed the basic leg entry procedure as well as a leg entry control board.

A permit to work, plus a leg entry certificate and leg sentry was required for all work in the shaft, including all categories of work and inspections not normally undertaken as part of watchkeeping duties. Prior to the issue of a leg entry certificate steps were taken to ensure that the shaft was safe to enter and that there was clear and safe access to and egress from the worksite. If it was considered unsafe to enter the shaft a notice to that effect required to be posted on the leg entry control board. A leg entry register was kept at the entrance to the shaft and used by the leg sentry to record all leg entries and exits.

A leg sentry required to be positioned at the entrance to the shaft, the control point, during the whole of the time personnel were working in the shaft. The duties of the leg sentry were to control entry, and he would refuse a person entry to the utility shaft if that person had no permit to work, to alert those in the shaft of any danger which may arise while they were in the shaft and to maintain telephone or radio contact with the working party and the control room. The leg sentry had authority to refuse entry to unauthorised persons and to order evacuation. The leg sentry required to warn those in the shaft of any danger outside which was likely to affect them and immediately instruct them to evacuate the shaft. The leg sentry required to be instructed in emergency procedures which applied on the platform and which may have been relevant to entry to the shaft.

When there was no requirement for a leg sentry (e.g. entry for operations first line maintenance, watchkeeping and safety checks by operations personnel, pre-entry checks, safety inspections by the platform manager or platform safety personnel, visual inspections by resident platform inspectors and accompanied visitors) the control point was the process control room and completions of the leg entry register required to be done by the process control room operator. However, the entry team must have included a person assessed as leg entry competent.

No person was allowed to enter the shaft until they, or the leg sentry acting on their behalf, had reported to the control room, and the control room personnel had confirmed that a current leg entry certificate was in force. The control room personnel could stop entry if there was reason to believe entry should not take place.

On entering the shaft the persons identity card required to be hung on the control board at the shaft entrance. Personnel could descend and ascend within the shaft by means of either the lift or the stairs. The lifts were used for the normal conveyance of personnel and the maximum allowable load could not be exceeded. The lifts required to be isolated under permit if work was ongoing in their immediate vicinity and presented a hazard to the work party. Tools and equipment required to be lowered to the worksite using either the platform crane or the winches provided.

Once the work party arrive at the worksite they required to establish contact with the leg sentry. All personnel entering the shaft had to be in possession of an approved safety torch, a gas monitor available to each work party and one member required to have a radio. An approved meter for monitoring oxygen deficiency and H₂S content must at all times have been located at the work place when personnel were in the shaft and a person trained in the use of the meter required to be present at all times and carried out atmosphere checks continuously until the men left the shaft. The person monitoring the atmosphere required to advise all personnel of any change in the condition of the atmosphere.

Communication with the control point had to be established immediately on entry into the shaft and the radio required to be checked on arrival at the worksite.

Sparging took place before entry to the shaft and not until H₂S was no longer detectable in the water. If sparging arrangements changed, all personnel had to leave the shaft and the atmosphere required to be re-tested prior to re-entry. Sparging could not be started when personnel were in the shaft. Oil accumulation on top of the water required to be removed, as much as was possible, prior to entry.

Deluge or sprinkler fire extinguishing systems required to be live throughout the period of work in the shaft and would activate automatically in the event of a fire.

If the utility shaft ventilation failed all work in the shaft required to stop and all personnel had to leave the shaft if imminent restart of the ventilation was not envisaged. The leg sentry had direct and immediate access to an approved breathing apparatus set.

On exiting the utility shaft the persons identity card required to be removed from the control board at the shaft entrance and his absence recorded in the leg entry register and reported to the control room.

In the event of a change of platform status personnel in the utility shaft required to stop all work and contact the leg sentry or the control room for instructions by radio or telephone. Personnel had to assemble at the stairway with breathing apparatus. Providing that evacuation did not entail moving up into an area of danger personnel had to evacuate the shaft via the stairway carrying breathing apparatus. One member of the working party had to monitor the atmosphere using the test equipment provided. On advice from the control room, or in the event of the instruments recording an abnormal atmosphere, breathing apparatus required to be donned. If possible, the work party had to vacate the shaft as a group. When the shaft had been evacuated the control room required to be informed. Immediately on leaving the shaft personnel had to report to their muster stations, leaving their breathing apparatus at the shaft entry point. If it was safe to do so the leg sentry had to return the leg entry register to the control room prior to him reporting to his muster station. If it was not possible to return the register the leg sentry required to contact the control room by telephone to report status.

If the leg sentry, or the control room, had not been contacted by the personnel in the shaft, following a change of platform status, then the control room had to take the initiative and attempt to make contact either by radio or by telephone. Once contact had been made with the personnel in the shaft the control room gave instructions either to remain at the worksite or to evacuate the shaft, depending on the reason for the alarm. If contact with the personnel in the shaft could not be made by the control room then the safety of the personnel in the shaft required to be established by physical entry following a full assessment of the risk of allowing additional personnel into the shaft.

(d) Operation of the Platform

(i) Produced vapour and liquid separation, and gas compression

In normal operation oil and gas is produced from the wells and flows up through the well conductors in the two southern legs of the platform and into the high pressure separator. The high pressure separator is a two-phase separator which separates the vapour from the liquids.

The high pressure gas, consisting of light hydrocarbons and water vapour, is sent to two stages of gas compression with pre-cooling and interstage cooling and is exported via the Brent system to St Fergus.

The liquids from the high pressure separator, which are a mixture of crude oil and produced water, flow to the low pressure separator. The mixture is predominantly water with some crude oil. The low pressure separator is a two phase separator and produces two streams, firstly, low pressure vapour and, secondly, a mixture of water and oil.

The low pressure vapour is sent to two stages of gas compression with pre-cooling and interstage cooling and this stream is blended with the gas from the high pressure separator for further compression, and export.

Liquids from the gas compressor knock-out drums are sent to the low pressure separator, with the exception of the low pressure compressor first stage knock-out drum liquids which are sent to the low pressure flare knock-out drum. The liquids from the low pressure separator, comprising a mixture of crude oil and produced water, are cooled in plate type heat exhangers. There are usually two parallel streams of crude oil coolers in use, with a spare stream available.

The crude oil is routed, normally via the three 8 inch oil rundown lines, within the utility shaft, to the 24 inch manifold and then to the storage cells at the base of the platform.

(ii) Product Storage

The amount of oil stored within the sixteen cells situated at the base of the platform varies depending on production schedules. To control the storage, settlement and export of the produced oil the sixteen storage cells are linked in four groups of four cells. At any one time one group of cells is being filled, one group is being emptied, and the remaining two groups are allowing the liquids contained therein to settle and separate.

The design of the platform substructure requires that the concrete cells remain in compression.

A ballast, or drawdown, system maintains the liquid levels for the cells within the design parameters. The internal level in the cell system is maintained by a static header tank. The level in the header tank is automatically adjusted by level control valves which pump produced water out to the top of the utility shaft for discharge, or allow seawater to enter the cells at an inlet point. The water is distributed to the storage cells below the oil/water interface through a manifold system within the minicell. All the storage cells contain sand ballast to a level of nineteen metres. The lines from the minicell manifold system penetrate the cells just above the sand ballast level and are used in conjunction with the drawdown system and level controls to maintain a permanent static head during oil import and export operations.

During normal production the produced liquids from the platform separation process are routed to the storage cells. Produced fluids currently comprise about 90% water and about 10% de-gassed crude oil. Produced fluids are transferred from the separation system in the platform topsides to the 82.7 metre level in the utility shaft through three 8 inch rundown lines. From the 24 inch manifold at the 82.7 metre level and a series of manifolds at the 77.2 metre level the co-mingled fluids free flow into the selected storage cell group through cell fill lines which extend from the utility shaft to the tope of the storage cells. When the required storage capacity has been reached the produced fluids are routed to another group of cells and the co-mingled fluids in the storage cell are left to separate out into their oil/water components.