Enhanced Oil Recovery Technologies

Morning Star Oil represents skilled expertise in the following EOR technologies

Liquid Carbon Dioxide Flooding

Carbon Dioxide is particularly effective in recovery efforts in oil reservoirs deeper than 2,000 ft., where CO2 will often be in a supercritical state.

In high pressure applications with lighter oil CO2 is miscible with the oil, with resultant swelling of the oil and a reduction in viscosity, and possibly with a reduction in the surface tension within the reservoir rock.

In the case of low pressure reservoirs or heavy oils CO2 will typically form as an immiscible fluid, only partially mixing with the oil. Some oil swelling may occur, and oil viscosity can still be significantly reduced.

In these recovery applications, between one-half and two-thirds of the injected CO2 returns with the produced oil and is usually re-injected into the reservoir to minimize operating costs.

The remainder is trapped in the oil reservoir by various means. Carbon Dioxide as a solvent has the benefit of being more economical than other similarly miscible fluids such as propane and butane. 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. Two mechanisms are at work to improve the amount of oil recovered.

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. A second mechanism is the physical displacement employing in a manner similar to water flooding, in which oil is meant to be pushed to the production wells. While 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

In a steam flood, also known as a steam drive, some wells are used as steam injection wells while ajacent wells are used for oil production. The two mechanisms are designed work in tandem to improve the amount of oil recovered.

The first effect is to heat the oil to higher temperatures, thereby decreasing its viscosity so that the oil flows more easily through the formation toward the producing wells.

A second mechanism is a physical displacement - employed in a manner similar to water flooding- in which oil is pushed to the production wells. While large amounts steam are needed this method is typically more effective at recovering a larger portion of the oil.

A form of steam flooding that can be considered is steam assisted gravity drainage (SAGD) in which two horizontal wells are drilled with one a few meters above the other, and with steam injected into the upper one. The intent here is to reduce the viscosity of the bitumen to the point where gravity will pull it down into the producing well.

Water Flooding

Water Flooding refers to the method discovered in Pennsylvania in 1885 where water is injected into the oil reservoir to increase pressure and thereby stimulate production. Water injection wells can be found both on- and offshore to substantially increase oil recovery from an existing reservoir.

Water is injected to support pressure of the reservoir (also known as voidage replacement), and to sweep or displace oil from the reservoir and push it towards a well.

Normally only 30% of the oil in a reservoir can be extracted, but Waterflooding injection increases that percentage (known as the recovery factor) and maintains the production rate of a reservoir over a much longer period.

Nitrogen & Gas Injection

Gas injection or miscible flooding is presently the most-commonly used approach in enhanced oil recovery. Miscible flooding is a general term for injection processes that introduce miscible gases into the reservoir.

A miscible displacement process maintains reservoir pressure and improves oil displacement because the interfacial tension between oil and water is reduced. This refers to removing the interface between the two interacting fluids. This allows for total displacement efficiency.

These types of process often involve an organic hydrocarbon chemical used to infuse oil in the formation with Super Heated Nitrogen and CO2. This process reduces surface tension while raising the gravity of the oil - thus potentially increasing production by up to seven hundred percent or more in most wells. As an added benefit this process often enhances production in wells in the surrounding area.

Gases used include nitrogen ,Co2, or natural gas. The fluid most commonly used for miscible displacement is carbon dioxide because it reduces the oil viscosity and is less expensive than liquefied petroleum gas. Oil displacement by carbon dioxide injection relies on the phase behavior of the mixtures of that gas and the crude, which are strongly dependent on reservoir temperature, pressure, and crude oil composition.