What's new in production

	Vol. 224 No. 6
ROBERT E. SNYDER, EXECUTIVE ENGINEERING EDITOR

 More on gas to liquids applications. Our Editor, Perry Fischer, offers a few comments on a recent announcement from FMC Technologies, Inc., that a joint-venture company, GTL MicroSystems, has been established between FMC and UK-based Accentus plc, a subsidiary of AEA Technology plc, for commercial development of gas-to-liquid (GTL) technology. FMC has a majority ownership interest in the JV. 

 Perry says, if the press release were taken at its word, this new GTL venture would change the world – or at least the oil field as we know it. The ability to monetize stranded gas reserves as low as 10 MMcfd, as the release says, implies that a 25-Bcf gas field in East Siberia can be economically produced. If not for the fact that FMC Technologies was involved, I might be too skeptical to write this (I’m not familiar with UK-based Accentus plc), Perry says. But FMCT has a good track record and, after a lengthy discussion with the new JV’s product champion, the technology does have merit. 

 First, although the press release said that this GTL process was profitable at gas rates as low as 10 MMcfd, this is a bit misleading. The target market, in this case, would be stranded associated gas, perhaps helped by anti-flare regulation, especially on FPSOs. In all cases, the technology is aimed at 200 MMcfd (20,000 bbl of GTL liquids) or less. 

 The key to all GTL processes is low Capex and high process efficiencies. Typically, Capex is in the range of $20,000 to $25,000 per throughput barrel of GTL product. Reducing this cost is the subject of several GTL start-ups in recent years. The usual methods involve lowering the cost of producing the initial synthesis gas, the use of proprietary catalysts (of which there are many), process optimization, co-location with LNG facilities and economy of scale. Some of these methods are utilized in plants being built (or nearly so) in the Middle East and Africa. 

 What makes GTL MicroSystems different is not just their proprietary catalyst of process, but the fact that they have bypassed the economy-of-scale cost reduction in favor of optimized fit-for-purpose scale. Basically, they are specializing on building some remarkably small process packages, especially aimed at offshore use. To do this necessarily means ultra-short contact times for reactions to occur. They have accomplished this through new designs in heat exchangers, contactors and the afore-mentioned proprietary catalyst. By focusing on what others have bypassed, this JV has a good chance of succeeding. A good background reference is Perry’s November 2001, World Oil article, “Natural Gas: Part 8 – Monetizing stranded gas.”

 This editor doesn’t appear so knowledgeable of GTLs judging from a comment in May’s production column under the heading “Alaska to US gas line.” Commenting on the need for more continental US gas, I said, no large reserves are being found onshore and rapid depletion of new finds doesn’t help the situation –  “development of offshore reserves and imports of LPG are the principal options.” What I meant to do was use LPG as a general term for any kind of hydrocarbon liquid produced from any kind of hydrocarbon gas. As one of our erudite readers pointed out, LPG is principally propane, with some butane and pentane. And the Dictionary of Energy notes that wet gas is 84.6% methane, 6.4% ethane, 5.3% propane and 2.6% butane. Dry gas is 96% methane. So methane is the principal target for GTL projects and LNG appears to be the major resource. 

 And don’t forget compressed natural gas (CNG). Natural gas can now be brought to the consumer by a fleet of ships using compressed natural gas technology. These ships will serve as both storage and transport vehicles discharging directly into the land-based gas grid via an offshore discharge terminal, an offshore platform or buoys. Det Norske Veritas (DNV) says analysis of different gas transportation solutions has shown that this new concept will be competitive with pipelines and LNG transport for distances of up to 2,500 to 3,000 nautical miles. The advantage is less investment in infrastructure and greater flexibility. 

 Different solutions for transport of gas by ship directly from the field to the consumer without liquefaction, regasification and storage plants have been evaluated for many years. The main problem that had to be resolved was to contain the pressurized gas without designing massive and heavy gas cargo tanks onboard the ships. This obstacle has been overcome, DNV says, by using experience and know-how from the pipeline industry. The new solutions can safely reduce steel weight of the cargo tanks by 40%. 

 The new ship type combines the features of a crude oil tanker and a container ship. The containment system may comprise a set of vertical pipes designed according to the principles used for pipelines. Ships have so far been designed to transport up to 30 million m³ of gas (about 1 Bcf) on each voyage. A complete set of rules for ships engaged in the transport of CNG has now been issued.

 DNV’s ambition is to further develop the rules to cover more of the CNG concepts now being developed. One such concept has been introduced by Knutsen OAS Shipping and has been developed with assistance from DNV and Europipe GMBH. A minimum of three vessels will be required to establish a continuous gas transport chain. Vessel delivery is expected to be possible within a 24-month period. More info can be found at: www.dnv.com.

 Oil recovery from Prestige tanker. Work to recover the oil from the sunken tanker Prestige will begin this summer, the Spanish government announced in April. But the project will be one of the most difficult salvage operations ever attempted, since the wreck is lying in two pieces in about 3,500-m water. Divers and existing robots cannot operate at such depths. Spain’s government has contracted Repsol YPF to retrieve the oil. Repsol has announced that its first goal is to develop remote-controlled vehicles that can work at great depth. These will inspect the ship and patch remaining leaks. 

 The robots will then attempt to make a hole in the wreck, to which they will attach a large bag, about 5 m wide and 20 m long. The oil should flow into this, and when full, the bag will be shuttled to surface, emptied and sent down again. Plan B is to erect a canopy like an immense marquee around the wreck, catch the rising oil in this and pump it to surface. As a last resort, it might be possible to pump oil straight from the vessel. Repsol devised its plan in consultation with other oil companies and salvage specialists. It has apparently not confirmed a firm operational schedule.