Search
Contact Us

t: (440) 561 0510

Linkedin Facebook-f X-twitter

Recovery factor

Recovery factor is the percentage of the oil or gas originally in place in a reservoir that has been, or is expected to be, produced. It measures how much of the resource a development actually recovers.

What is recovery factor?

Recovery factor expresses efficiency. It divides the volume produced, or expected to be produced, by the volume originally in place in the reservoir. A field that will produce 30 million barrels from 100 million barrels of original oil in place has a recovery factor of 30 percent.

It is closely related to estimated ultimate recovery (EUR): EUR is the volume, and recovery factor is that volume as a share of what was there to begin with.

Typical recovery factors

  • Conventional oil reservoirs. According to the U.S. Department of Energy, primary recovery typically yields about 10 percent of original oil in place; waterflooding and other secondary methods bring that to about 20 to 40 percent; and enhanced oil recovery offers prospects of 30 to 60 percent or more.
  • Shale and tight oil. Recovery factors are much lower. The U.S. Energy Information Administration’s 2013 global shale assessment used recovery factors for shale oil generally in the range of 3 to 7 percent of oil in place.
  • Gas. Gas reservoirs generally have higher recovery factors than oil reservoirs, because gas flows and expands more readily.

Why shale recovery factors are low

In unconventional reservoirs, the rock’s extremely low permeability means oil can reach a well only from rock close to a hydraulic fracture. Oil in the rock matrix between fractures is held by very small pores and high capillary pressure. Improving recovery factor in shale is therefore a question of how much rock the fractures contact and how well oil can move from the matrix into them, which is where completion design and fluid chemistry come in.

Frequently asked questions

It depends entirely on the reservoir type and development method. A recovery factor that is excellent for shale oil would be poor for a conventional waterflooded field.

In conventional reservoirs, by waterflooding and then enhanced oil recovery methods. In shale, through completion design, well spacing, refracturing and treatments that improve how fluids move between the rock and the fractures.

  • Estimated ultimate recovery EUR

    Estimated ultimate recovery (EUR) is the total amount of oil or gas a well, field or reservoir is expected to produce over its entire life, counting what has already been produced plus what remains to be recovered under a given development plan.

  • Enhanced oil recovery EOR

    Enhanced oil recovery (EOR) is any technique that recovers oil left in a reservoir after natural pressure and waterflooding have done what they can, by changing the properties of the oil, the rock or the fluids between them. The main types are thermal, gas injection and chemical EOR.

  • Residual oil saturation Sor

    Residual oil saturation (Sor) is the fraction of a rock's pore space that is still filled with oil after it has been swept by a displacing fluid such as water. This oil is trapped by capillary forces and will not flow under normal waterflood conditions.

Sources

  1. recovery factor, SLB Energy Glossary
  2. Technically Recoverable Shale Oil and Shale Gas Resources (2013), U.S. Energy Information Administration
  3. Enhanced Oil Recovery, U.S. Department of Energy, Office of Fossil Energy and Carbon Management