The Aussies are building a giant LNG platform for service 200 km.s offshore. The 600,000 ton vessel will be 6 times the size of an aircraft carrier. The FLNG may be just the ticket for shut-in gas on the North Slope or the Mackenzie Delta.
Shell Development (Australia) Proprietary Limited (Shell) will be developing its Prelude FLNG Project approximately 200 kilometres offshore northwest Western Australia. Shell will use a Floating Liquefied Natural Gas (FLNG) facility designed to extract and process natural gas and associated condensate, thereby avoiding the need for a “traditional” development comprising offshore platforms, export pipelines, an onshore liquefaction plant and export jetty. After processing at the site of the gas field, ocean-going LNG carriers will offload liquefied gas, chilled to -162 Celsius and shrunk in volume by 600 times, and other products, directly from the facility out at sea for delivery to markets worldwide. Until now, the liquefaction of offshore gas has always involved piping the gas to a land-based plant.
The vessel will house a steel, double-hulled floating facility, approximately 480 m in length by 70-80 m wide. Upstream facilities including subsea production wells and manifolds; subsea flowlines; riser base manifolds; flexible risers that transport the gas, condensate and any produced formation water to the FLNG facility; and, umbilicals used to control the wells. The FLNG facility will not disconnect during bad weather and is designed to withstand severe weather
including a 1 in 10,000 year weather event. The facility will be held in position by four groups of six anchor chains, arranged around the FLNG turret. The chains are secured by suction piles which penetrate deep into the seabed.
The Prelude FLNG Project is scheduled to commence production in 2016 with an estimated operational life of 25 years. Annual production is estimated to peak at 3.6 million tonnes of LNG.
Shell notes “Prelude and Concerto have around 3 trillion cubic feet of liquids-rich gas. The relatively small size of the gas fields and the remote location make them an ideal candidate for development via Shell’s FLNG technology as it would not be economic to develop the gas via a conventional onshore LNG processing plant.”
Alaska and NWT both have massive stranded natural gas reserves on their north coasts. Each jurisdiction is pursuing the concept of a pipeline south to carry such gas to market. But the cost has proven too high to attract investor interest. The figures tossed around are $40-60 B for a a pipeline from the North Slope to SW Alaska, with a large LNG facility. The Mackenzie Valley pipeline would cost $20 B and would aim to sell into the weak North American Gas Market.
As an alternative, investments could be made to accept a FLNG vessel off the North Slope and off the shore of Tuktoyuktuk for 3 months every year. During the ice free 120 day season 1.2 M tonnes of LNG would be produced. Before freeze up the FLNG would head south. Cost,~$2 B for near shore facilities + FLNG rental. Big permanent liquifaction facilities are very expensive. Perhaps the solution could be to rent the capacity on a seasonal basis. It’s worth a FLiNG.