A FT-GTL Technology for Small-Scale Applications

Abstract

Stranded gas wells are reserves of natural gas (NG) that have been discovered but deemed unusable due to physical or economic reasons owing to the reserves being too small or in remote locations. The financial implications of transporting (piping) of the gas, coupled with the quantity of gas available per well, often render using this gas infeasible. However, it is estimated that as much as 40% of the world’s NG reserves are found in stranded gas wells. This is equivalent to the energy represented by the oil reserves of Saudi Arabia, and embodies billions of dollars of unutilized assets! Most available gas processing technologies are only applicable for large-scale applications. That is, applications that are much larger than the amount of gas in found in a typical stranded gas well. Thus, in order to maximize on the NG in stranded gas reserves, a novel approach to design and applicability was required.

An investigation, in the form of a feasibility study, was conducted to evaluate the technical, environmental and economic aspects of a Fischer Tropsch Gas-To-Liquids (FT-GTL) facility of the scale suitable for application with stranded gas reserves. The GTL plant would consume NG and produce a syncrude. Syncrude is more valuable and easier to transport than NG, and in principle can be utilized in existing infrastructure to produce a wide range of fuels and chemicals. A re-look at the technical design of the plant was necessary since the current thinking for large-scale GTL would result in the entire project being uneconomical – this was done by using a process synthesis approach to assess the major drivers for small-scale technology.  Part of the design considerations also included designing a plant that could potentially be modularized and self-sufficient so that on-site processing at a gas reserve could be achieved without any other infrastructure. The outcomes of the feasibility study showed that the proposed process flow sheet is technically very viable, with the resulting economics shown to be in line with existing large-scale GTL plants.