The Three Phases of Oil Recovery

In the recent years, due to increase in the demand of energy there has been an up-rise in the oil yielding activities across the globe. The process of extraction of oil from below the surface is called oil recovery. There are many factors that can obstruct the free flow of oil to the surface of the well and therefore, needs to be accounted for. These factors include, but are not limited to, the viscosity of the oil deposit and the porosity of the rocks.

n earlier years, due to absence of sufficient technological means, only a portion of the available reserve which was often as low as 10% could be recovered from the fields. However, today, with modern technology at our disposal, oilfield operators are able to extract as much as 75% of the total reserves. This has not only enabled higher production, but also better utilization of resources.

Oil recovery takes place in three phases; primary, secondary and tertiary, enabling optimum utilization and extraction. Here's what each phase entails -

Primary Phase Recovery

In this phase, the first reliance is on the underground pressure to force the oil to the surface of the field. This oil is extracted and processed. Once the pressure drops, artificial oilfield equipment, such as pumps, are used to fetch more liquid to the surface. The gas lift technique is also used in the primary phase, wherein natural gas is pumped back deep into the well, which then expands and sends more oil to the surface. This technology is often the primary phase choice for offshore fields. Primary phase recovery accounts for only 10% of oil extraction for a reserve.

Secondary Phase Recovery

Secondary phase recovery technique is the most applied technique in crude oil recovery systems. This phase uses water to further extract oil from the grounds. In this phase, water, that is produced in the initial phase of drilling, is separated from the oil and is again injected in the well below the oil. This in return brings more oil to the surface, and can account for another 20% of oil extraction from the field. This method not only boosts oil extraction, but also disposes off the produced water, sending it back to its origin.

Tertiary Phase Recovery

Tertiary phase recovery, commonly known as enhanced oil recovery (EOR), is an expensive but effective form of extraction. There are three techniques used within this phase - thermal recovery, gas injection and chemical flooding. In this phase, any of the mentioned techniques can be used to lessen the viscosity of the oil, enabling it to rise to the surface of the field. This is a very effective technique and can account for 50% or more of oil extraction and leads to optimum utilization of the reserve.

These are the three phases of oil recovery, and operators must evaluate the fields to understand if all the three phases of recovery are required or not.

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Created on Dec 31st 1969 18:00. Viewed 0 times.

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