About Mature Fields
The interactive graph above represents typical production rates through the primary, secondary, improved, and enhanced recovery stages. In this example, improved and enhanced recovery methods increased overall production by 20%.
Current global trends in energy supply and consumption are out of balance. Since 1980, consumption has increased steadily and annualized reserves have decreased. To address this unsustainable situation, the industry has two options: pursue new reserves through exploration or focus on improving ultimate recovery from existing "mature" fields.
Mature fields represent an ever growing segment of global reserves. Analysts agree that most of the world's giant fields have already been found. With fewer new field discoveries and more mature fields, increasing importance is being placed on maximizing ultimate recovery. Mature fields typically still contain about 30% of their original gas and 65% of their original oil.
The Production Life Cycle
Every producing reservoir has a life cycle. The primary phase is characterized by the recovery of hydrocarbons by natural mechanism such as its pressure. This period is marked by a high volume of production that declines relatively quickly. The secondary recovery phase includes the use of basic techniques such as injecting water into the reservoir or using artificial lifts to generate additional hydrocarbon flow and manage pressure. Secondary recovery activities have long been an industry standard.
A field is considered “mature” when overall production has declined significantly, following primary recovery efforts or when all of its “easy” hydrocarbons have been produced. Increasing ultimate recovery of these fields can involve extending the peak production period of the field or flattening the decline curve itself through secondary, improved, and enhanced recovery methods. However, extracting oil or gas from mature fields presents specific challenges. These fields are often marked by old equipment and infrastructure. Water can also be a problem, because mature fields produce far more water than oil, raising potential environmental issues.
Fortunately, new technologies are allowing greater percentages of hydrocarbon to be produced economically. Revamping facilities, “smart” infill wells, and the injection of gas, steam, or chemicals are all among the improved and enhanced recovery methods being successfully employed to give new life to mature fields.