A new process for well-head gas upgrading

As oil-prices and environmental concerns are increasing, it is of interest to better use the well-head gas. This light fraction co-produced with petroleum is generally flared and in this paper a method for upgrading and returning the co-product to the petroleum stream is suggested. The method is based on a conversion of the gas to synthesis gas and upgrading this synthesis gas into liquid hydrocarbons. But as the placement of such systems would be remote, the design has been performed using the following criteria. First of all the system has to be robust in design and secondly it has to be self-sustaining in that no additional feedstocks or chemicals are required for its operation and thirdly, the product should be crude oil compatible.In the paper, the system has been outlined, the major unit operations designed and heat and mass balances have been determined. Six cases have been compared, differing in reforming and oxygen generation technology. The comparison has been made on both a technical and production economic premises. In each case the investment cost has been determined and from this, and the calculated produced hydrocarbons, a production cost per barrel has been determined.The production of hydrocarbons well-head gas is a viable route and the production cost for the hydrocarbons vary between $71 and $156 a barrel, with the lower cost being quite attractive with the crude prices of recent years (around $100 a barrel). The production cost is however heavily influenced by the investment cost and the fact that the stranded natural gas is considered free. The production of an alternative, upgraded fuel would be a possibility; this however warrants additional investment in both production equipment and infrastructure.

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► Using the well-head gas for producing additional liquid hydrocarbon product.
► Robust and stand-alone system with no additional infrastructure requirement.
► Production cost for best case in the $60 to $75 a barrel range for a 100 MW system.