Elf Enterprise Caledonia Ltd. has installed a 23,000 metric ton jacket for the Piper 9 platform, starting construction for the first of a new generation of North Sea production platforms.
The company, successor in the North Sea to Occidental Petroleum (Caledonia), plans to lift topsides ont) the jacket during the North Sea autumn. The operation will include the world's heaviest single lift, 10,500 metric tons of integrated deck, production, and utilities module.
A crew of 600 will work 1 million man-hours during 6 months to complete the hookup and enable first oil from Piper B to be produced during the summer of 1992.
The float-out and installation of the jacket came 3 years after the explosion and fire that engulfed the Piper Alpha platform and killed 167 workers.
Piper Alpha was one of the largest of the first generation North Sea platforms and had only a passing exterior resemblance to its successor. Occidental says Piper B has been designed to be one of the safest platforms in the North Sea.
SAFETY PRINCIPLES
The design incorporates four safety principles aimed at ensuring that a tragedy on the scale of Piper Alpha is never repeated.
Many members of the Piper Alpha crew perished because they obeyed standing instructions and remained in the accommodation unit to await rescue.
On Piper B there would be no waiting in the accommodation unit in an emergency. Personnel would move directly from the muster area into the U.K. North Sea's first freefall lifeboats and wait for the order to launch.
The freefall boats are the primary means of evacuation. Entry into the lifeboats from the muster areas in the positively pressurized accommodation unit will be through pressurized hatches that close automatically once the boats are launched.
Piper B's temporary safe refuge-a requirement on all new U.K. North Sea platforms-will be the living quarters, designed to withstand a major hydrocarbon fire for 2 hr. Maintaining the quarters at positive pressure will exclude smoke in an emergency. Key areas of the platform, including the accommodation module, will be supported by structures designed to withstand fire for at least 2 hr.
The Cullen inquiry into the Piper Alpha tragedy highlighted the need for protected escape routes. On Piper B there will be at least two escape routes from every point on the platform. Key access ways have been designed to provide safe refuge for at least an hour.
SAFETY'S PRIORITY
Design and construction of Piper B emerged from an organization where the engineer no longer reigns supreme. Safety managers have equal stature, and the safety plan, drawn up at the beginning of the project, has top priority.
Piper B may set trends for North Sea production platforms because of the safety concepts in its design and the overall system of quality management that governs project activity.
From the beginning, designers specified acceptable risk levels, which were included in the project safety plan.
Kombiz Hashemi, loss prevention manager for Piper redevelopment, described the project safety plan as a mandatory document that establishes the status of safety within the project prior to design. It forms the basis for the formal safety assessment and is interlinked with the safety management system.
Safety was designed into, rather than added to, the project. Initially, Hashemi said, it was hard to instill this new thinking into the design and engineering teams. But the principles were established with Piper and are second nature to people working on the follow-up Saltire project.
The quality management system (OMS), which encompasses safety as one of its main elements, was specially developed by the project to govern every task and function.
Jim Gibson, project quality assurance manager for Piper redevelopment, said one of the keys to developing a safe project is a OMS in which senior managers can be sure that their plans and objectives are being fulfilled. This is achieved through a continuous schedule of internal and external auditing.
QMSs require all management systems to be amalgamated into a network of control. The system is verified and monitored by independent experts.
Independent external assessors from Bureau Veritas Quality Ltd. measure Piper B's QMS for compliance with British Standard BS5750, the International Standards Organization ISO9000, and European Normal EN 29000, identical internationally recognized quality standards.
Piper B and the nearby Saltire field development project are the first offshore developments to achieve this status, although several other U.K. operators are in the process of qualifying for the standard.
In addition to regular QMS assessment, independent safety checks are carried out by Veritec of Norway to ensure strict compliance with safety criteria.
Veritec engineers may raise any safety variance questions with the project team. Veritec has been authorized to discuss noncompliance directly with the operator's managing director in the event of a serious disagreement, although in practice disputes rarely need to be taken this far.
A test of the QMS and safety management system will come this month when Elf Enterprise submits the Piper B safety case to the U.K. Health and Safety Executive, who will use it alongside a number of other early safety case submissions in advance of publishing draft regulations on the subject later in the year.
PIPER DESIGN
Occidental began redevelopment of Piper, which has remaining reserves of 165 million bbl of 37 gravity crude, while the Cullen public inquiry was still in progress.
The project team decided to use an eight-leg jacket and 27,000 metric ton topsides. For the 140 million bbl Saltire field, on Block 15/7 about 4 miles from Piper, it will use a four-leg steel platform due on stream near yearend 1992.
The 24 well Saltire platform will have first stage separation. The 45,000 b/d of 41 gravity oil and 50 MMcfd of gas will be transferred to Piper B and blended with production there. The oil will be carried through the pipeline to Flotta in the Orkney Islands. Gas will be piped to Claymore or the MCP10 compression platform on the Frigg gas line.
Tom Rees, engineering manager for Piper redevelopment, said Elf used quantitative risk analysis in examining seven or eight topsides layouts to arrive at the current layout sequence of wellhead module, production and compression, nonhazardous utilities, and accommodation.
Blast walls have been installed between each section, while nonhazardous areas act as additional shields for the accommodation unit.
The layout, he said, requires a longer and narrower platform and is much roomier than anything seen before. To reduce blast pressure, the layout of vessels was examined, and the density of equipment in the process area was cut.
Personnel accustomed to the normal design of North Sea platforms will not recognize the process areas on Piper B, Rees said. The walkways are big and airy, which will facilitate escape and enable crews to remove major items of equipment and send them to the beach for repair.
The objective is to do as little repair work on the platform as possible and as much onshore. That requires open areas to get equipment in and out. The design also provides the materials handling equipment to get the equipment to shore. Big items like vessels will stay put. Equipment where maintenance problems are expected, such as rotating equipment, pumps, and large valves, can all be removed.
Key platform equipment operators on the design team favor the deliberately reduced level of offshore maintenance. Allowing more maintenance to be undertaken onshore could lead to smaller offshore crews.
The design provides alternative escapeways to temporary safe refuge, one of which must be available format least an hour after an incident. The escapeways are not fully enclosed or pressurized, like the accommodation unit, but they are heat-shielded and designed to criteria in the safety plan.
Rees said current plans call for crews to go to muster' areas in the accommodation unit and wait in the six freefall lifeboats, linked by pressurized hatches to the muster area. Three more freefall boats are available at the wellhead module end of the platform. Each lifeboat can accommodate 45 people, giving a seating capacity 200% more than total crew numbers. In addition to the statutory number of life rafts, there will be "donuts" enabling workers to lower themselves into the sea by rope. There will also be knotted ropes as a last resort.
Another design feature that emerged from the presence of operational people on the design team was the siting of the muster area in a "dirty" area of the accommodation unit, allowing exercises to be conducted without disrupting clean areas.
CONTROL ROOM
Everything on the platform is monitored and controlled from the control room, removing more people from hazardous areas. Control room operators can lock out rotating pumps and all other rotating equipment so that nobody at the workface can activate items by mistake.
The control room is below the accommodation unit in the integrated deck. Everything is duplicated in the control room-there are even two control system loops around the platform designed to keep instructions flowing even if there are one or more nodal breaks. Similar systems have been available in refineries and petrochemical plants, but this is the first time one has been used offshore.
System functions will be recorded on the platform and onshore, making it possible to trace the source of problems. Designers also paid close attention to effective, fail-safe public address systems and to controls to prevent the entry of smoke and gas into the accommodation area.
Copyright 1991 Oil & Gas Journal. All Rights Reserved.
