Abstract

One of the major natural gas reserves in Indonesia is found in the Natuna 'D Alpha' gas field. This is not only a large gas deposit (222 TCF), but is also interesting because it is composed predominantly of CO₂ (71%). The last development scheme proposed by the oil companies Exxon and Pertamina for the utilisation of this gas, before the crisis of 1997, was for the CO₄ to be sold as LNG, while the CO₂ was to be injected back below the ocean floor. However, the marketing of natural gas depends on long-term and high-risk contracts or requires strong commitment between the producer and the buyer, even long before the development stage.

An alternative marketing strategy would be to convert the natural gas mixture to syngas (CO + H₂) by the partial oxidation and dry reforming of methane with carbon dioxide; the syngas can then be used for the production of a wide variety of chemicals and fuels using gas-to-liquids (GTL) technology, e.g. Sasol or Shell's SMDS.

This has three major advantages compared with the LNG route: i) less separation stages will be needed and the cost of gas injection below the sea floor will be lower, since there will be much less CO₂ remaining after the reforming process; ii) dry reforming is an effective way of incorporating CO₂ in the products, which will eventually end up, for example, as fuel powering an engine; and iii) the prices of the end products are much higher and easy to market as compared with LNG. In this study, it will be shown that molybdenum and tungsten carbide catalysts are active and stable for the process of partial oxidation and methane dry reforming to syngas using a feedstock of high CO₂ content natural gas, such as that found in the Natuna 'D Alpha' field, Indonesia.