Steam injection as an oil recovery mechanism

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Steam injection is a mechanism of enhanced oil recovery under which oil and natural gas can be extracted from subsurface formations, for this purpose steam is injected trying to stimulate the formation through the thermal action of steam injection, where the reservoirs containing hydrocarbons are heated to stimulate and produce oil.

Two technologies are influential in the steam injection, one of them is the cyclic stimulation with water steam, and the other technology is the steam flood injection, it is important to emphasize that both technologies have an important degree of application only for shallow oil reservoirs, since shallow oil reservoirs have a high viscosity at the native temperature found in the formation.

It is logical to think that with steam injection we can stimulate oil production, since the higher the temperature, the lower the viscosity that binds the kerosenes to the rock surface and also the mobility of the oil trapped in the rock can be improved.

Cyclic steam stimulation (CSS)

This steam injection technique consists of injecting water steam in a cyclical way, that is to say, in stages, so it can be said that these stages consist of a stage where only steam is injected to heat the formation in a considerable period of time. The second stage is influenced by the time variable, since it is necessary to wait for the steam to act before the oil formation and for all the fluid contained in the rock to be in optimal conditions to flow. As a third stage, what remains is to produce the oil, which already has an optimum viscosity to be extracted to the surface.

Once the injection cycle operated in the three stages mentioned above is completed, the injection cycle is repeated in this way, thus obtaining a fairly optimal process where it is possible to obtain 20% of the original oil from the site, the steam injection temperatures that are handled operationally are quite high, which can range between 300 to 340 degrees Celsius, continuous injection can last several weeks or months, After this step it has to rest and stop injecting steam to allow the steam to penetrate the formation and do its work, and the third step which is to produce also last a similar time to the stages of injection and rest, where oil is pumped until it begins to fall pumping flow, which means that you have to start repeating the cycle.

Conclusion

A clear example of a hydrocarbon contained in shallow oil formations that has a very high viscosity and that is a faithful candidate to apply any steam injection technology is the one in the Orinoco oil belt in my country Venezuela, either by cyclic steam injection, or by steam flooding where steam can be injected through the drilling of wells that will later operate as injectors, which can heat the formation horizontally, and then as a result of gravity and with a lower viscosity, the oil can flow to the wells considered as producers, the latter is considered as the technology called steam assisted gravity drainage (SAGD).

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Steam injection to recover oil that cannot be extracted from the subsoil by conventional mechanisms is a method that goes beyond fields that have exhausted their energy to produce by its own energy, since steam injection has been able to establish oil recovery mechanisms in fields containing bituminous or high viscosity oil.

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References

Steam Injection for Enhanced Oil Recovery

Thermal In Situ Oil Sands

Solvents in situ: the Hybrid Car of the Oil Sands

Steam-assisted gravity drainage