Thermal Recovery Methods

Thermal recovery methods, are used to heat the crude oil in the formation to reduce its viscosity and/or vaporize part of the oil.

Thermal Recovery Methods Methods include cyclic steam injection, steam drive and

in situ combustion.

These methods improve the sweep efficiency and the displacement efficiency of heavy crude.

Steam Injection Steam injection is an increasingly common method of

extracting heavy oil.

It is the main type of thermal stimulation of oil reservoirs, with the two main ones being Cyclic Steam Stimulation and Steam Flooding.

Cyclic Steam Stimulation This method, also known as the Huff and Puff method,

consists of 3 stages:

injection soaking production

Injection

Steam is first injected into a well for a certain amount of time to heat the oil in the surrounding reservoir to a

temperature at which it flows.

Soaking

After it is decided enough steam has been injected, the steam is usually left to "soak" for some time after (typically not more than a few days).

Production

Then oil is produced out of the same well, at first by natural flow (since the steam injection will have increased the reservoir pressure) and then by artificial lift.

Production will decrease as the oil cools down, and once production reaches an economically determined level the steps are repeated again.

Production

The process can be quite effective, especially in the first few cycles. However, it is typically only able to recover approximately 20% of the Original Oil in Place (OOIP).

Steam Flooding

In a steam flood, sometimes known as a steam drive, some wells are used as steam injection wells and other wells are used for oil production.

Steam Flooding Two mechanisms are at work to improve the amount of

oil recovered:

Reduction of viscosity Physical Displacement

Viscosity Reduction

The first is to heat the oil to higher temperatures and to thereby decrease its viscosity so that it more easily flows through the formation toward the producing wells.

Physical Displacement A second mechanism is the physical displacement

employing in a manner similar to water flood , in which oil is meant to be pushed to the production wells.

More steam is needed for this method than for the cyclic method, it is typically more effective at recovering a larger portion of the oil.

steam flooding which has been reported to recover over 50% of OOIP.