As with crude oil, the transportation of natural gas isn’t always straightforward. Rather than coming directly from a well and straight to your home or business, natural gas must navigate a carefully planned highway of pipes, valves, stations, and processing plants before the final product gets to you. A significant portion of this transportation network involves the gathering system, responsible for taking “wet” gas from the wellhead to either a mainline pipeline or processing plant.
But how is this process different from (and similar to) oil production? One of the major traditional differences between onshore gas wells and oil wells is that the gas well in a majority of cases ushers wet gas through a small-diameter gathering pipeline elsewhere for processing. The oil well on the other hand — particularly if it’s connected to a small reservoir — will simply have a storage tank on site that collects the crude for vehicular retrieval. However, larger capacity oil wells are different, and like gas wells they’ll also move collected crude elsewhere for processing. Another difference between the two is that gas wells may at times have field processing equipment attached at or near the wellhead, usually in the form of separation equipment to remove water, oil, and other impurities before moving the gas along. This onsite processing isn’t typical, however, of many oil wells. Finally, one similarity between the two: both gas and oil wells may require beam pumping units in cases when production pressure is insufficient.
Once collected from one or more wells, the gas moves through a network of flow control piping and manifold systems. If multiple feed lines are in close proximity, they will often connect to a manifold which can then meter the flows from each well and optimize distribution to better meet production goals. From these manifolds the collected gas moves to a larger gathering trunk line, typically 18 inches in diameter and made of steel. The trunk line is buried at least four feet underground and routed based on local, regional, and federal regulations. If travelling long distances, compressor stations are placed along the line, with the compressors placed in their own “buildings” with insulation to dampen noise levels for the surrounding environment. These stations are necessary to maintain pipeline pressure and flow (the gas moves from higher to lower pressure). Finally, if necessary, the gas will reach a processing station, where additional impurities are removed and condensate separation occurs.