Key Insights
- The 2019 Abqaiq attack knocked out 5% of global oil supply in a single strike — energy sites were hardened on the ground, so attackers went to the air.
- Refineries, terminals, and fields span square kilometers. Hardened cages don’t detect inbound drones.
- Passive acoustic detection covers large perimeters affordably, catches autonomous and fiber-optic drones, and runs on solar in remote locations.
Energy facilities are built to stop intruders on the ground: fences, guards, access controls, hardened buildings. None of that reaches a drone flying over the fence. A drone can surveil a site, map its layout for a later attack, or deliver a payload onto equipment that is expensive and slow to restart.
Passive acoustic detection fits these sites because it’s legal, covers large industrial perimeters without breaking the budget, and catches the small and autonomous drones that other systems miss.
Why the threat is real
One event made the exposure clear. On 14 September 2019, drones and cruise missiles struck Saudi Aramco’s Abqaiq and Khurais facilities and knocked out roughly 5.7 million barrels a day — about 5% of global supply. It was the largest single supply disruption in the history of oil. Prices jumped immediately. Gulf refineries can need one to four weeks to restart after an emergency shutdown. Aramco reportedly committed billions afterward to hardening and redundancy.
The lesson was specific: energy sites had been fortified against bombs and armed intruders for decades, which is exactly why attackers went to the air, where defenses were thin. Drone strikes on Gulf refineries have continued, and capable drones keep getting cheaper.
For most commercial operators, the everyday threat is less dramatic but constant: unauthorized surveillance, reconnaissance of a site’s layout, safety incidents from a drone near hazardous processes, and the insurance and regulatory exposure that follows an undefended perimeter.
Why energy sites are hard to protect
- The perimeter is huge. Refineries, terminals, and fields span square kilometers. Covering that with expensive point systems is impractical.
- Hardening does not detect. Cages, barriers, and blast walls raise the difficulty of a strike but give no warning that a drone is inbound.
- Small and autonomous drones evade legacy systems. A low-metal drone barely reflects radar. An autonomous or fiber-optic drone carries no radio link for RF to intercept.
- Sites are often remote. Wiring and powering a dense sensor network across a distant field is a real constraint.
- Emitting adds risk. Around volatile processes and sensitive operations, adding more active emitters isn’t always welcome, and jamming is restricted.
Why acoustic detection fits oil, gas, and critical infrastructure
Acoustic sensors only listen. They emit nothing, so they add no interference around sensitive operations and need no RF license. That matters at a refinery where every piece of active equipment has to be justified.
Coverage scales by density, not unit cost. At low thousands per sensor, a site rings its full boundary with a mesh rather than buying one costly installation. Askalon field tests reached 1 km detection on a 1 kg drone.
The sensors catch the drones that matter. Small, low-flying, autonomous, and fiber-optic drones all produce motor noise — the one signature every powered drone emits, whether or not it carries a radio link.
Solar or grid power and an IP67 ruggedized housing let sensors sit on perimeters far from infrastructure. That suits fields and terminals off the grid, where running power and data cable isn’t practical.
On detection, the sensor alerts a control room and staff phones. A blind perimeter becomes one that reports an inbound drone in time to respond. Under current regulations, disabling a drone is reserved for designated authorities — detection feeds a human decision, not an automated countermeasure. Pair acoustic with optical for visual confirmation once a drone is flagged.
Be clear about scope. Acoustic detection is an early-warning and situational-awareness layer. It reports the drone — mitigation follows through the site’s security procedures and the relevant authorities. It does not by itself stop a determined state-level strike. What it does is remove the blindness that made energy sites vulnerable from above in the first place, and it addresses the surveillance and incursion threats that operators deal with daily. In the EU, this maps to obligations under the Critical Entities Resilience framework to detect and respond to physical threats.
What to look for in an energy-site drone detection system
- Passive operation with no emissions, safe around volatile processes.
- Detection of small and autonomous drones, not only radio-controlled ones.
- Coverage that scales across a multi-kilometer perimeter at reasonable cost.
- Ruggedized, low-power sensors that run on solar in remote locations.
- Real-time alerting into the site control room and security.
Frequently Asked Questions
What happened at Abqaiq in 2019?
Drones and cruise missiles struck Saudi Aramco’s Abqaiq and Khurais facilities, knocking out roughly 5.7 million barrels per day — about 5% of global oil supply. It was the largest single supply disruption in the history of oil. The attack demonstrated that energy sites hardened against ground threats were effectively undefended from the air.
Can’t radar cover an oil facility?
Radar struggles with small, low-flying, and low-metal drones — the kind that matter most for surveillance and attack. It also costs significantly more per unit, which makes covering a square-kilometer perimeter impractical. Most radar systems are built for aircraft, not consumer drones.
What about drones with no radio signal?
Autonomous drones flying GPS waypoints and fiber-optic drones with a physical tether both fly without emitting a radio control signal. RF-based detection misses them completely. Acoustic detection works on the drone’s motors and propellers — the one signature every powered drone produces.
How many sensors does a site need?
It depends on the site’s footprint, topography, and ambient noise profile. A site-specific acoustic assessment determines the count, but the 1 km detection range means most facilities are covered by a modest sensor mesh rather than a dense grid.
Is acoustic detection reliable in industrial noise?
Yes. Drone propellers and motors produce sound in frequency bands distinct from industrial machinery. Askalon’s algorithms are trained to isolate drone signatures from background noise — the system filters out what isn’t a drone.
Bottom Line
Energy sites spent decades hardening against ground threats. Attackers adapted by going to the air, where defenses are thin and the barrier to entry keeps dropping. Passive acoustic detection is not a countermeasure — it’s the early-warning layer that tells you a drone is inbound so your security procedures and the relevant authorities can act. It catches the drones that legacy systems miss, runs on solar in remote locations, and removes the blindness that made these sites vulnerable from above. For EU operators, it’s a direct fit with Critical Entities Resilience obligations to detect and respond to physical threats.
If you’re responsible for security at an energy facility or critical infrastructure site, get in touch — we’ll help you assess what coverage looks like for your perimeter.
Last updated: July 2026. Reviewed by the Askalon Industries engineering team. Askalon Industries builds passive acoustic drone detection sensors in Lausanne, Switzerland.
