The AICD may appear unremarkable. However, put into in a well, the valve can considerably increase oil production—thanks to a simple physical mechanism. Just like in Gänserndorf, Austria, where OMV is using the technology for the first time.
It fits easily in one hand, weighs just a couple of hundred grams and looks pretty unspectacular at fast glance. And yet this small disc, known as an AICD (Autonomous Inflow Control Device), is capable of something which oil companies like OMV have long been searching for.
Sometimes the simplest inventions are the best. The AICD makes oil production much more efficient—with the help of a simple mechanism.
The AICD is a valve that is used in a horizontal oil well to block low-yield liquids like water or gas. Since February 2014 Peter Soroka has been dealing with a prototype for one simple reason: In Great Britain, OMV has several West of Shetland developments in water depths from 400 m to 1,000 m where the production conditions are not always the most straight forward. This is why the Canadian is looking for technologies that improve the ability to produce more oil. In the course of his research Peter Soroka came across AICD and is convinced by its capabilities: “It’s simple and clever. And it works without electricity or hydraulics, using only a physical dynamic effect that was discovered centuries ago.”
Thanks to Bernoulli: More efficient oil production
He is talking about “Bernoulli’s Principle”, discovered by the Swiss mathematician Daniel Bernoulli in 1738, which states: When a fluid quickly flows by an object, it will create negative pressure. This explains why an airplane flies or a shower curtain billows inward when the water is on. The AICD brilliantly makes use of this effect, explains Peter Soroka: AICDs are placed along the reservoir section in a horizontal oil well at regular intervals. Inside the device is a moveable plate that opens or closes the AICD, depending on which fluid is flowing through it. Flowing oil, for example, is viscous, which is why it presses the movable disc away from the well bore and opens the valve. The opposite is true for water or gas, which have lower fluid viscosities and therefore flow at much higher speed through the AICD. This creates a decrease in pressure, where the disc is sucked towards the well bore and closes the valve, which blocks water or gas and prevents them from reaching the surface.
AICD in action
At the end of 2014 Peter Soroka presented the AICD to his OMV colleagues in Austria—and they were also won over by the technology: In mid-2015 a total of 17 valves were used in the “Bockfliess 208” well in Gänserndorf. This is the first time that the AICDs were used within OMV, explains Thomas Florian, who is managing the reservoir. And as with every device being tested for the first time, says the Subsurface Manager at OMV Austria, there was a familiarization phase with the AICDs: “In the first four to five weeks of operations we were faced with a relatively weak performance.” One of the reasons for this was that more water had accumulated in the deposit than we were expecting. And because the role of the AICDs is to slow down production from areas with higher water production, the production rate in the first weeks fell short of expectations.
However, explains Thomas Florian, the situation improved suddenly after six weeks: “The dilution fell by two percent and the production rate improved as well.” At present 185 barrels of oil a day are being produced—that is far higher than the maximum assumed rate of 140 barrels of oil a day. The next months will show how the AICDs will influence the well long term. But one thing is already clear to Thomas Florian: “The AICDs work—and they make an important contribution.”