New waves aid oil recovery

With the conflict in the Middle East highlighting oil shortages in other parts of the world, with the price of oil constantly changing, and with no viable substitute for gasoline readily available for worldwide adoption, it has come to the attention of the world that oil producers simply need to produce more oil. When you consider that more than 60% of all oil remains trapped in oil reservoirs, this doesn’t sound like an unreasonable demand. However, producers often face challenges when it comes to maximizing production and recovery. And since the world uses roughly 84 million b/d of oil, any technology that can boost oil production and recovery is in high demand.

Initial production typically results in 10 to 30% recovery. Secondary recovery can increase recovery by 10 to 20%, and tertiary recovery, which can be fluid injection, can increase recovery by an additional 15 to 25%. Recent moves by the United States Congress have made these technologies even more important in America as it works to increase American oil independence.

Let’s take a look at some methods that oil companies are currently using to increase recovery such as traditional methods like CO₂ and fire flooding, and recently popular methods like porosity dilation.

CO₂ flooding has attracted a lot of attention as a viable tertiary recovery method. The process begins with carbon dioxide being injected into an oil reservoir via injection wells. The gas reduces the viscosity of the oil so that it flows more freely. Water is then injected to sweep the oil and CO₂ to producing wells. The use of CO₂ in flooding can thin the solution, which can result in fingering and poor recovery of the hydrocarbon. The injection of the water helps to reduce the chances of this. A side effect of this solution alternation is that when CO₂ is mixed with water it forms a highly corrosive carbonic acid. This is important to note because it may mean that you need to outfit your wellheads with stainless steel seals, bolts and other trimmings if you have not already done so and are considering CO₂ injection. The CO₂ can then be extracted from the oil and reused many times.

Though it can be difficult to fully combine CO₂ with heavy oils, CO₂ is still soluble in oil, causing the fluids to swell. This trait of CO₂ makes it far more efficient than liquefied petroleum and natural gas. The CO₂ that is injected can come from naturally occurring reservoirs, but new technologies are being developed to produce CO2 from industrial applications for use in areas without access to the CO₂.

Fire flooding is another option available to those without ready access to CO₂ and is growing in popularity, particularly in the US Midwest. In fire flood applications, a medium composed largely of oxygen, ozone or a combination of the two, is injected into a heavy oil reservoir. Once in the reservoir, this mixture is ignited and produces a product that is fundamentally gaseous CO₂ and water vapor. This product, and the additional heat generated by the combustion, lowers the viscosity of the nearby oil, theoretically forcing it to form an oil bank and move toward the recovery wells.

One of the major drawbacks of fire flooding is that it will often leave a large amount of heat behind. Many new methods are being developed to offset this issue, but wet combustion actually looks to take advantage of it. With wet combustion, water is injected simultaneously in hopes that it will use the heat and transfer it to the oil bank, making the oil more efficient and reducing its air requirements. Some of the drawbacks that have prohibited this from receiving mass adoption have been liquid-blocking problems and the fact that its use is largely limited by the oil viscosity.

A newer method that is being introduced into the market is pressure pulse technology. This method is an injection technology wherein, with each pulse, a volume of liquid is introduced through a casing or tubing and is forced at high accelerations by downhole devices into the reservoir. The injected fluid then increases the porosity, pressure, permeability, saturation and homogenization of an ever-increasing coherent volume of the porous media through porosity dilation.

The objectives of the injection technology are to enhance fluid injection, sweep efficiency and dispersion, as well as to provide pressure support. During the process the elastic pore volume dilates and contracts. This results in large inertial effects at the pore-throat scale, which provide additional forces to the liquids. These can help overcome the pressure barriers that arise because of the surface tension, helping the immobile phase to traverse through the pore throats and establish phase continuity, allowing for greater mobility for the oil and greater production for your well.

The facts remain; increasing oil production is a worldwide concern. The United States is hoping to reduce its dependence on foreign oil, the United Kingdom and Norway have launched several initiatives to maximize recovery, and even Saudi Arabia is looking to increase its oil production using enhanced oil recovery methods. And with so many new technologies, like pressure pulsing, being used and developed; it is clear that the world is on the right track to maximizing recovery in existing wells. These results could potentially change production in heavy and light oil deposits. In today’s atmosphere of war, shortages and constraints on exploration, what could be more important than that?