The reason for this is that, unlike oil and coal, natural gas is usually carried (after cleaning to remove water oil and any other contaminants) through a pipeline that often runs (via additional pumps) directly to the customer. They, in turn, don’t usually store it, but burn it as needed, drawing the supply straight from the pipe. The problem that this gives the marginal producer is that the gas in the line must be at a certain pressure if it is to move down that pipe to the customer, and then come out of the nozzles at sufficient flow to be useful. That pressure has to be achieved, at the well once the natural pressure of the gas in the well has fallen over time and production, with a compressor, which cost money to install, run and maintain. At a certain point in the well life the gas being produced falls below the point at which it becomes economic to pay for that compressor (which is only a part of the total costs that an operating well will incur). It may even be (at the rates of decline being seen in many current wells) that the decline is so swift that as soon as the natural pressure falls below that needed for the pipeline, that the well closes and a compressor is never economical. In these cases the well life may well only be three or four years, rather than the fifty of the company model.