Production is the longest phase in the well’s life and may last for years or even decades. Over time, production declines and, eventually, will be too low to continue to operate the field. But, during a field’s productive life, the operator monitors well performance and intervenes periodically to perform maintenance and repairs, and try to stem the rate of decline.
Different phases of production are known as primary, secondary and tertiary recovery. Oil and gas in a reservoir is naturally under pressure and may need no encouragement to flow to the surface; primary recovery occurs when hydrocarbons flow spontaneously. In some wells, however, there is insufficient pressure or the oil is too viscous to flow freely. Various technologies, such as electrical submersible pumps, can be used to get the hydrocarbons moving.
Even in reservoirs that are highly pressured when production starts, the operator will eventually need to intervene to keep up the flow rate. In secondary recovery, natural gas or water are injected into the reservoir to displace oil and drive it to the surface. Tertiary recovery, or enhanced oil recovery, involves the injection of steam, gas, chemicals or microbes to change the properties of the hydrocarbons in the reservoir, and make them easier to extract. In unconventional wells, drilling is accompanied by hydraulic fracturing, which opens up pathways in the impermeable rock through which fluids in the rock may flow into a wellbore.
Abandonment and decommissioning
When an oilfield no longer contains sufficient hydrocarbons to justify the continuation of production operations, the operator fills in wells, dismantles and removes equipment from the site, and restores the area. Typically, around a third of reserves are economically recoverable and increasing recovery factors is one of the industry’s main aims.
Abandonment and decommissioning
When an oilfield no longer contains sufficient hydrocarbons to justify the continuation of production operations, the operator fills in wells, dismantles and removes equipment from the site, and restores the area. Typically, around a third of reserves are economically recoverable and increasing recovery factors is one of the industry’s main aims.
