Expanding the world's third largest producer of liquefied petroleum gases is a complex and demanding process. Plant production must go forward as normal while the construction work, such as installation of new equipment, welding and tie-ins continues.
While the Karsto facility is usually operated by about 75 people on site, the expansion project will flood the plant with up to 1200 workers. As the number of workers on the site increases, so does the risk potential. "The sheer size of the project has implications on the overall risk picture at Karsto," says Statoil's staff engineer Finn Roar Berg.
The Karsto complex, located north of Stavanger on the west coast of Norway, plays a key role in the transport and processing of gas and condensate (light oil) from the Norwegian continental shelf. It receives and refines gas from fields in the North Sea via the Statpipe trunk line system and from the Norwegian Sea via the Asgard Transport pipeline.
However, Karsto is currently being equipped to take on even bigger tasks. A project called the Karsto Expansion Project 2005 (KEP 2005) is now in place and the construction phase has already begun. With a budget of NOK 5.75 billion, KEP 2005 is Norway's second largest industrial project on land after the Snohvit development, another Statoil project currently underway in northern Norway.
"Statoil is committed to zero tolerance for accidents at Karsto. So far, we have succeeded," says Berg. "In order for us to continue to operate safely during the expansion project, we must have a clear and quantifiable risk overview. DNV has carried out several risk assessments, enabling us to project how our methods to manage and minimize the risks affects the overall safety level."
"By using DNV's risk assessment methods, we can calculate how many people can be at the site at the same time and what type of work they can carry out at certain stages without exceeding the accepted risk levels. This allows us to carefully plan how and when to do the necessary construction work during operation," says Berg.
The benefits of careful planning
According to Arild Samuelsberg, sector manager of processing technology in the Natural Gas Business Area, Statoil spent a lot of time and energy on the concept design phase. "With strict safety criteria, often demanding up to three safety barriers, the solutions and workarounds are carefully analysed and compared to other solutions," he says. "By basing our planning on risk calculations, we have been able to identify risks that we can manage by going for optional solutions, such as prefabrication of parts. This reduces the amount of work that actually takes place at the site."
During construction, some parts of the facility will be shut down and in the summer of 2004, the entire plant will be shut down for 22 days. Shutting down such a complex facility is a complicated and expensive solution, one that Statoil seeks to avoid. But Samuelsberg explains that, "There are certain things that can only be carried out safely when the plant is shut down. In such cases, we don't hesitate to do it, but we make sure that the work is well planned, well executed and moves forward without any surprises."
"The ability to simulate many different scenarios for the work progress allows us to be up front in planning the project," says Berg. "With projects as big and complex as these, no one can afford to go for a solution and then decide to abandon it when the project is underway. Every solution must be verified in advance according to the variables that might occur."
Through a frame agreement, DNV carries out a number of various risk management work for Statoil at Karsto, from risk assessments to the day-to-day planning and execution of Risk Based Inspection. Berg says there are several benefits to working with DNV. "First, they are familiar with our work processes and systems. Second, they provide Simulating and calculating scenarios
excellent services, and we appreciate their continuity and stability. Knowledge and competence is dependent on the expertise of individuals, and we recognize the advantages of working with the same people on a long term basis."
The KEP 2005 development project has been designed to equip the Karsto processing complex with the capacity to handle gas from Statoil's Kristin project in the Halten Bank area of the Norwegian Sea. Rich gas from this field will be piped to the complex through the existing Asgard Transport trunk line. By late 2005, the processing capacity for rich gas at Karsto will be expanded by 44 percent. KEP 2005 will also increase annual ethane recovery capacity from 620,000 to 950,000 tonnes. After commissioning and start-up, the new facilities will come into operation on 1 October 2005.