After the wells are completed through hydraulic fracturing, the operator removes the rig and installs a wellhead, also referred to as a “Christmas tree” due to the many valves sprouting from it. The valves control pressure in the well and permit the flow of oil or gas to the flowlines. The remaining infrastructure on the pad is required for gas storage, produced water storage or treatment, and pipeline infrastructure (see Figure 4).
In the natural gas industry, the phases of development and production are not distinct, with production beginning soon after the wells are completed and connected to the gathering systems. This often occurs while the site is still in development. 1 After the gas emerges from the well, it may first be sent to a processing station to remove impurities. Then gathering lines convey the natural gas to a compressor station that pressurizes the gas for longer-distance transport. From there, the product is piped to export terminals or to end users like residences and businesses (see Figure 5).
In the case of oil production, the product is transported through flowlines to a local gathering station. It is then sent to a refinery to be processed; finally, it is transported either to market or to export facilities.
Once the well pad has turned over to the production phase, work activity slows principally to monitoring the site. The operator reduces its workforce to fewer, longer-term staff. Over the lifetime of the well—which could be 10–50 years—periodic activities may take place to re-stimulate production and perform maintenance. When the production of oil or gas begins to decline, the operator may seek to enhance production by re-fracturing the well, depending on the geology of the source rock at the site. Specialized teams of workers may periodically visit the site to conduct re-fracturing, perform routine maintenance on aging equipment, or perform workovers, a more extensive overhaul of the equipment. Therefore, while there is a decline in activity in the post-development phase of production, work at the site continues intermittently for many years.
- Dutton and Blankenship, “Socioeconomic Effects,” 7-8. ↩