Many documents are known describing processes for the conversion of (gaseous) hydrocarbonaceous feedstocks, especially methane from natural sources, e.g. natural gas, associated gas and/or coalbed methane, into liquid products, especially methanol and liquid hydrocarbons, particularly paraffinic hydrocarbons. At ambient temperature and pressure these hydrocarbons may be gaseous, liquid and (often) solid. In these documents reference is often made to remote locations and/or off-shore locations, where no direct use of the gas is possible. Transportation of the gas, e.g. through a pipeline or in the form of liquefied natural gas, requires extremely high capital expenditure or is simply not practical. This holds even more in the case of relatively small gas production rates and/or fields. Reinjection of gas will add to the costs of oil production, and may, in the case of associated gas, result in undesired effects on the crude oil production. Burning of associated gas has become an undesired option in view of depletion of hydrocarbon sources and air pollution. A process often used for the conversion of carbonaceous feedstocks in liquid and/or solid hydrocarbons is the well-known Fischer Tropsch process.
In WO 94/21512 a process for the production of methanol has been described from an off-shore natural gas field using a floating platform. However, no integrated, efficient, low-cost process scheme has been described.
In WO 97/12118 a method and system for the treatment of a well stream from an off-shore oil and gas field has been described. Natural gas is converted into syngas using pure oxygen in an autothermal reformer, a combination of partial oxidation and adiabatic steam reforming. The syngas (comprising a considerable amount of carbon dioxide) is converted into liquid hydrocarbons and wax. No fully integrated process scheme for a highly efficient, low capital process is described in this document.
In WO 91/15446 a process is described to convert natural gas, particularly remote location natural gas (including associated gas), in the form of normally liquid hydrocarbons suitable for fuel use via methanol/dimethyl ether. However, no integrated, efficient, low-cost process scheme has been described.
In U.S. Pat. No. 4,833,170 a process is described for the production of heavier hydrocarbons from one or more gaseous hydrocarbons. The gaseous hydrocarbons are converted into syngas by autothermal reforming with air in the presence of recycled carbon dioxide and steam. However, no (energy) integrated, efficient, low-cost process scheme has been described.
In CA 1,288,781 a process for the production of liquid hydrocarbons has been described comprising the steps of catalytically reforming the hydrocarbonaceous feed, heating the reforming zone by means of a carbon dioxide-containing heating gas comprising a product which has been obtained by partial oxidation of reformer product, separating carbon dioxide from the heating gas, catalytically converting the reformer product after separating off carbon dioxide into liquid hydrocarbons and combining the carbon dioxide obtained above with the hydrocarbonaceous feed used in the catalytic reforming process.