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The world's largest gas-to-liquids plant is now fully online
The world's largest plant to turn natural gas into cleaner-burning fuels and lubricants, Pearl GTL, achieved full production towards the end of 2012.
Pearl shipped its first product in June 2011, around three months after first start-up. The plant achieved full production towards the end of 2012. It will process around 3 billion barrels of oil equivalent over its lifetime from the world’s largest single gas field, the North Field in the Arabian Gulf. The field stretches from Qatar’s coast and contains more than 900 trillion cubic feet of gas, equivalent to 150 billion barrels of oil.
The gas-to-liquids (GTL) plant, a joint development by Qatar Petroleum and Shell, provides nearly 8% of Shell’s production worldwide — making it one of the company’s key projects. It has a capacity of 260,000 barrels of GTL products and natural gas liquids per day.
The plant produces cleaner-burning diesel and aviation fuel, oils for advanced lubricants, naphtha used to make plastics and paraffin for detergents. It makes enough diesel to fill over 160,000 cars a day and enough synthetic oil each year to make lubricants for more than 225 million cars. The products reach customers in every major energy market through Shell’s global retail network.
In bringing Pearl to production, Shell engineers built on more than thirty years of experience in gas-to-liquids technology. The company built the world’s first commercial-scale GTL plant in Bintulu, Malaysia, in 1993. On a daily basis, Pearl’s output of GTL products is almost 10 times greater than Bintulu’s.
Building Shell’s biggest engineering project to date in Ras Laffan, a vast industrial zone on Qatar’s coast some 90 kilometres north of Doha, was a major feat. It took one million hours — the equivalent of 500 years of full time work for one person — to complete the conceptual design of the world’s largest gas-to-liquids plant. It took five years and 500 million man hours to build it. Tens of thousands of workers were trained to make sure all the sections of the plant were well built and started up smoothly.
In designing and constructing Pearl, Shell drew on the experience of building major projects all around the world. Thousands of supervisors and craftsmen at the Pearl GTL plant were trained to make sure the lessons learned were taken on board and applied during construction and commissioning of the plant.
Despite the massive number of workers involved and the complexity of Pearl’s construction, a strong safety culture helped Qatar and Shell achieve a record-breaking 77 million hours worked onshore without injuries leading to time off work.
Sixty kilometres offshore, natural gas from the North Field — discovered by Shell in 1971 — is now flowing from two platforms standing in water up to 40 metres deep to feed Pearl GTL. Eleven wells were drilled for each platform in record drilling times for the field.
Two underwater 76–centimetre (30-inch) diameter pipelines are carrying the natural gas to a gas separation plant onshore that extracts natural gas liquids: ethane for industrial processes, liquefied petroleum gas (LPG) for domestic heating and cooking, and condensates as a feedstock for refineries. The separation process also removes contaminants like metals and sulphur. The sulphur is turned into pellets and shipped to the nearest market to make hydrosulphuric acid, fertiliser or other valuable products.
Turning gas into liquid fuel
The pure gas, or methane, that remains then flows to the GTL section of the plant, where it is converted in a three-stage process into a range of gas-to-liquids products using Shell proprietary technology.
Finally, the liquid hydrocarbon wax is upgraded using specially developed technology involving new catalysts into the range of products. It takes some 2,000 steps to prepare all GTL systems for production.
In Qatar, summer temperatures exceed 40°C (104°F) and rainfall is slight. Conserving water is critical. Pearl was designed to be self-sufficient in its use of water.
Pearl, the largest investment by Shell in any single project, is a fully integrated project spanning production from an offshore gas field to finished marketable products. Shell funded 100% of the development costs under a profit- sharing agreement with the State of Qatar.
*source: Oil & Gas Journal