Extending the Life of Oil Fields, Revitalizing Waterfloods Using Pulsed Injection
It is anticipated that the average price at the gas pump in the US may climb as high as $5 per gallon by summer’s peak driving season. Understandably, many are worried that continuing turbulence in the Middle East could propel prices even higher. However, a process known as pulsed injection offers potential new life for US oil fields that were previously believed to be past their productive lifetimes, permitting additional barrels to be extracted domestically. In total, the US Department of Energy estimates that there might be as much as 430 billion barrels of oil that is technically recoverable in the US.
Before the development of pulsed injection, an oil company tasked with extracting additional oil from an older field would inject various fluids, mainly water, underground to help recover it—an operation known as secondary recovery. But there exists an overall drawback to this approach: Injected fluids have a tendency to seek the path of least resistance through porous media, tracing a different trajectory followed by the inaccessible oil and resulting in lower overall oil recovery rates.
In opposition to this conventional approach lies a process known as pulsed injection, which is comparable to what occurs when a kink is released from a garden hose. Specialized equipment oscillates the flow of water on and off, building up kinetic energy that will impel more water to come into contact with oil. Each surge of water and energy puts additional oil in contact with water when it might otherwise have stayed out of reach.
This process can enhance oil recovery using two main mechanisms: First, the pulsed injection of water overcomes the path of least resistance and enhances the so-called “finger density” of oil through the field. Second, the momentum of the pulsed fluid breaks up residual oil globules that exist underground. Both of these mechanisms make it far simpler for oil to be recovered from the field.
The potential prize of improving rates of recovery with pulsed injection is considerable. A one-percent increase in recovery equals 2 billion barrels of additional reserves globally; a five-percent increase in recovery—a conservative increase thought to be achievable—would produce an extra 300 to 600 billion barrels. Ultimately, the use of pulsed injection can result in enhanced oil recovery from a field of between 5 and 10 percent depending on reservoir conditions.
The use of pulsed injection processes similarly reframes the argument over “peak oil.” In his 2010 book When Oil Peaked, geologist Kenneth Deffeyes wrote that world oil production traces a bell-shaped curve, with the maximum occurring sometime within the last decade. The supergiant oil fields that supply much of our oil, he wrote, are aging and decreasing in production; furthermore, the oil fields we have found to date contain 95 percent of all the oil we will ever find. In making these points, Deffeyes was following the lead of his mentor, the “peak oil” pioneer M. King Hubbert.
Yet Deffeyes and all the other “peak oil” theorists who have emerged since Hubbert first published his claims in 1956 have failed to ponder one major influence on oil production: the advent of innovative technology. The fact is that continuing innovation in oil extraction, including the use of pulsed injection processes, offers fresh life for oil fields once believed to be depleted, making it difficult to identify a past or future “peak” in production.
A related application of pulsed injection is designed to aide in-ground environmental groundwater remediation cleanup strategies. This variant process has been shown to be a highly fruitful approach for introducing remedial fluids into aquifers. Verified as an effective environmental remedial strategy by Environment Canada’s Environmental Technology Verification Program, this process is capable of obtaining results that are unattainable by conventional injection methods. It helps treat environmental sites quickly and at minimal cost by broadly distributing remedial fluids throughout the aquifer.
The pulsating action forces remedial fluids into contaminated underground sites to effectively reach contaminates. The technology works within a wide range of soil and rock conditions and can access hard-to-reach locations, even under buildings. It offers several advantages in an environmental cleanup. First, it eliminates or greatly reduces problematic remedial fluid surfacing (daylighting) during injection. Second, the pulsating action produces a momentary expansion of the effective porosity, allowing injected fluid to enter pore networks not accessible to conventional pumping technologies. Third, the low-maintenance design of pulsed injection tools allows for on-the-fly adjustments to match site-specific characteristics. Finally, operators can use standard piping/fitting to connect pulsed injection tools between the injection pump and a standard injection well or direct push injection point.
In conclusion, pulsed injection processes can assist in maximizing ultimate oil recovery from existing and new oil fields and facilitating groundwater remediation efforts.
Brett Davidson is President and CEO of Wavefront Technology Solutions Inc., an Edmonton-based leader in fluid injection optimization for improved performance and profitability in the oil and environmental sectors. He can be reached at firstname.lastname@example.org.
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