For example, the water vapor containing in gas can form hydrates or, being condensed, accumulate at various locations (bends in the pipeline), disturbing gas advance; the hydrogen sulfide can cause strong corrosion of gas equipment (a pipe, capacity of heat exchangers). Besides preparation of the gas, it also is necessary to prepare the pipeline. For this purpose, they use nitrogen units to create an inert environment in the pipeline.
Gas is prepared in various ways. In the immediate vicinity of the deposit they construct comprehensive gas treatment unit, where gas cleaning and drying is made in absorption columns.
If gas contains a large amount of helium or hydrogen sulfide, they treat gas at the gas processing plant where they allocate helium and sulfur.
Currently, the main type of natural gas transportation is pipeline. Gas is under pressure pumped through pipes. In process of gas advance on the pipeline it loses a potential energy, overcoming frictional force both between gas and a pipe wall, and between gas layers, which is dissipated as heat. Therefore, at certain intervals in the duct they construct compressor station in which gas is compressed to a pressure typically from 55 to 120 atm and then it is cooled. Construction and maintenance of the pipeline is very expensive, but nevertheless it is the cheapest way to transport gas to small and medium distances in terms of initial investment and organization.
Besides pipeline transportation it is widely used special gas tankers (gas carriers). These are special vessels on which gas is transported in the liquefied condition in specialized isothermal capacities at a temperature from −160 to −150 by °C. To liquefy gas is cooled at elevated pressure. Thus, for the transportation of gas in this manner, it is necessary to lay a gas pipeline from the mine to the nearest sea coast, to built on the shore the LNG and pumping terminal, which is considerably cheaper than a regular port, and also tankers. This method of transportation is much more economical than the pipeline, because the cost does not depend on transportation, but on loading-unloading operations, but it requires higher initial investment in infrastructure than a pipeline. Its advantage is: LPG is safer for transportation and storage than compressed one.
There are other technologies of gas transportation, such as specially equipped automobile and railway tanks.