Qatar focus: US$18 billion Pearl GTL

Pearl GTL will be the world’s largest plant converting natural gas into 140,000 barrels per day of clean-burning liquid transport fuel and other products. The project will also produce 120,000 barrels of oil equivalent per day of natural gas liquids and ethane.

Since the project launch in July 2006 progress has been good. The project is proceeding in line with expectations at the time of final investment decision (FID). Onshore, over 40 000 workers are now building the two-train GTL plant and numerous items of major plant equipment have been installed. Offshore, drilling continues.

Shell’s Andy Brown, Pearl GTL managing director, explains how the Pearl gas to liquids plant is transforming the Ras Laffan landscape.

“Pearl GTL is an enormous complex of 20 kilometres by 10 kilometres, which is about 80 kilometres north of Doha. Offshore from here is the North Field, it’s the largest gas reserve in the world; 900 trillion cubic feet of gas, and the Pearl GTL project has been allocated a block in the North Field 24 kilometres long by 12 kilometres wide in which we are now drilling wells, that will produce gas which will come 60 kilometres through a pipeline to the Pearl GTL plant when we start up production.”

The proprietary Shell Middle Distillate Synthesis (SMDS) process will be at the heart of the two-train Pearl GTL plant. Developed over the course of three decades, the process has been proven on a commercial scale at the 14 700-barrel-per-day Bintulu GTL plant in Malaysia, which began operation in 1993. The Bintulu experience helped improve the chemical catalysts integral to the SMDS process. These improvements will reduce unit capital expenditure, allow faster processing and should enable Shell to produce greater volumes of fuel and other products at Pearl.

“With that gas, the first thing we need to do is clean up the gas. And what we can do is we take out condensate; we take out LPG which is then sold – exported from Ras Laffan here, but also we take out all the sulphur, and what we then get is clean natural gas that can go into our GTL process here,” explains Brown.

The other ingredient needed for GTL is oxygen. At the Ras Laffan site air is compressed and chilled to about minus 180ºC. At this pressure and temperature oxygen and nitrogen separates and the oxygen can be removed from the air. “We will produce 28,800 tonnes per day of oxygen, and that’s the largest oxygen plant constructed in one place in the world ever,” explains Brown.

Two of the world’s largest Hydrocrackers are already in place in the plant, ready to turn the gas and oxygen mix into GTL products such as diesel fuels, lubricant oils, detergent feed stocks, and petrochemical feed stocks. When we this reaction takes place the plant will actually make as much water as a by-product as it will hydrocarbon products.

To handle that water the plant will house a massive effluent treatment plant to clean up all the water making it ready for reuse. “There is no discharge of water to the sea whatsoever, it’s a complete reuse system – We think the largest process water reuse system ever built in the world before now,” explains Brown.

The water treatment plant alone has a capacity of 300,000 barrels a day. That’s enough capacity for a city of around one million people.

“That water comes back and one thing that we use it for is the steam system. In this plant there are lots of reactions going on that produce heat – we need to capture that heat and reuse it, and we do that through steam.” Pearl GTL will produce 8,000 tonnes per hour of steam, and Brown adds it is the largest steam system put together anywhere in the world to date.

“That steam is used to run the air compressors on the air separation units here. Each of the eight air separation units has a 70-megawatt air compressor, which is driven by produced steam.”

By integrating the processes with the rotating equipment needs the plant optimises its energy efficiency.

“Pearl GTL is linked to the North Field with 900 trillion cubic feet of natural gas – that’s over 14% of the whole world’s gas resource – is hardwired to this plant. So, you can imagine, this plant has a very, very long-term future.”

Pearl is scheduled to come onstream in And a project which will be one of the engineering marvels of the world, but also will provide clean fuels and products for customers across the world for many many decades,” he concludes.

Cutting Drilling Time

With rig costs running to tens of thousands of dollars a day, cutting down on time makes good commercial sense. A time of 75 days to complete a production well in the North Field was considered a good performance. Shell is completing wells for Pearl GTL in as little as 45 days. In all Pearl is on track to deliver 22 wells with a total saving of more than 600 days relative to what was considered good performance.

The jackets of the permanent Pearl 1 and Pearl 2 platforms are already in place offshore. A temporary deck has been installed on each jacket. These temporary decks are used to carry out the entire second stage of the operations at the same time that the first stage is conducted by the much larger mobile drilling rigs positioned over the temporary decks.

“We modified the rig and installed a nine-storey staircase and elevator between jacket and rig and a gantry crane below the rig to handle perforating guns,” says Bart Lismont, Shell’s upstream manager in Qatar.

“It’s quite incredible, the rig is cranked up twelve storeys high above the water to allow for the perforation activity below,“ adds Lismont.