Table 1 shows the gas-field-size requirements and typical world-scale plant sizes for some of the gas utilization options. The gas-field-size requirements are based on a single-train plant with a 20-year life. A combination of different gas monetization options also can be used depending on the available gas reserves. Table 2 compares the total market size for the different products for year 2001. Figure 1 depicts the impact of an additional 1,000 MMscf/D of gas on the product market.
Converting gas to liquids (GTL) through the Fischer-Tropsch (FT) route to monetize stranded gas has received increasing attention over the past few years. FT technology is a process that rearranges carbon and hydrogen molecules in a manner that produces a liquid, heavier hydrocarbon molecule. In general, GTL through the FT route refers to technology for the conversion of natural gas to liquid; however, GTL is a generic term applicable to any hydrocarbon feedstock. This page focuses on GTL processes based on natural gas feedstock. FT chemistry originated during the early 1920s from the pioneering work of Franz Fischer and Hans Tropsch at the Kaiser Wilhelm Inst.
It is widely accepted that global natural gas demand will continue to grow for the foreseeable future, possibly doubling every decade. Major new upstream developments, together with midstream transportation systems and downstream feedstock projects, are already progressing in all world areas. As this gas revolution evolves, there will be a dramatic rise in the requirement for high-accuracy measurement at every point in the gas value chain (Figure 1). Within these categories, there is a huge array of different gas-metering applications and a similar number of potential solutions. This can lead to confusion when selecting the optimum solution for the application.
Stranded gas is essentially gas that is wasted or unused. Estimates of remote or stranded gas reserves range from 40 to 60% of the world's proven gas reserves. The local market for gas is usually too small, or the gas field is too far from the industrialized markets. Sometimes excess gas reserves can be classified as stranded because they may result in oversupply of the market. Most stranded gas reserves are in gas fields that are totally undeveloped.
Natural gas is of little value unless it can be brought from the wellhead to the customer, who may be several thousand kilometers from the source. Because natural gas is relatively low in energy content per unit volume, it is expensive to transport. The cost to transport energy in the form of gas is significantly greater than for oil. This is one of the key hurdles to the increased use of gas. The most popular way to move gas from the source to the consumer is through pipelines.
Compressed natural gas (CNG) transportation is used in very small systems in environmentally sensitive areas. Sometimes the gas is transported to remote filling stations for CNG-fueled vehicles. Large-scale transportation of CNG is not yet commercialized but is considered economically feasible and is being pursued actively by several companies. In the 1960s, Columbia Natural Gas of Ohio tested a CNG carrier. The ship was to carry compressed natural gas in vertical pressure bottles; however, this design failed because of the high cost of the pressure vessels.