Published May 2003
Proven world natural gas reserves, which currently represent about 83% of the energy equivalence of proven oil reserves, have been growing at a faster rate. In some remote locations, wellhead costs of "stranded" natural gas have been estimated to be below $0.25/MMBtu, while the cost of reinjecting "associated" gas from crude oil production as an alternative to flaring may greatly exceed its value.
Fischer-Tropsch synthesis (FTS) generally involves the synthesis of hydrocarbons and oxygenates from synthesis gas (syngas) consisting primarily of a mixture of CO + H2. When configured to maximize the production of paraffinic hydrocarbons, the resulting intermediate product mix is often described as "synthetic crude oil" (syncrude). Such syncrudes can be readily refined into desirable distillate fuel fractions such as kerosene, naphtha, and heating oil using conventional petroleum refining techniques. Even though FTS is a technically proven gas-to-liquids
(GTL) technology, the conversion of natural gas to syncrude as opposed to higher value chemical products such as chemical grade methanol has only relatively recently been perceived to be a potentially viable commercial proposition. Recent advances in FTS technologies, particularly with regard to natural gas reforming, coupled with anticipated increased demand for "clean" diesel fuel appear to be enhancing the economic viability of this route to GTL. Since most of world's gas reserves are in the form of relatively small fields which would be inadequate for world scale GTL production capacities, interest is also increasing in new GTL production technologies which may be viable at low production capacities below 12,000 bpd. With 25% of world gas reserves located offshore, of particular interest would be GTL production technologies which would be barge mountable - such as on floating production, storage, and offloading
(FPSOs) vessels which are finding increased use in the development of oil fields in remote deep water tracts with no alternative economical outlet for any associated gas. The focus of this review is the small-scale GTL production via BP's "compact" reformer technology as mounted on an FPSO. Not only does their compact reformer unit have a much smaller "footprint" compared with conventional steam methane reformers (SMRs), but it also eliminates the need for a cryogenic oxygen unit as typically required by conventional oxygen blown reformer technologies. Minimizing the plot space requirement appears to be an essential element in the economic feasibility of such GTL applications.