Knowing What Your Methane Sensor Missed Quantifying Detection Probability in Airborne Gas Surveys

This application covers apparatuses, systems and methods for characterising how well a gas measurement system detects emissions as a function of emission rate, expressed as a probability of detection function, and then using that function to estimate the plumes the survey did not see. The applicant is Bridger Photonics, Inc., a remote sensing company in Bozeman, Montana.

The Problem

Aerial methane surveys fly a sensor over oil and gas infrastructure and report the leaks it finds. The results are used to prioritise repairs, to report emissions to regulators and increasingly to underpin claims about how much a facility is emitting in total.

The difficulty is what the survey does not report. Every sensor has a detection threshold that varies with conditions, and small plumes fall below it. A survey that finds twenty leaks has not established that there were only twenty. It has established that twenty were above the detection limit under that day’s conditions, which is a different statement and not a useful basis for a total emissions figure.

Historically this has been handled with a single sensitivity number, some minimum detectable emission rate quoted for the instrument. That is a crude summary of a process that is really probabilistic. Detection depends on the emission rate, on how noisy the gas concentration measurement is, and on the wind speed carrying the plume, and the transition from undetectable to reliably detectable is a gradient rather than a cliff edge. Without a proper account of that gradient, there is no defensible way to translate what was found into what is actually there.

What This Invention Does

The method characterises a measurement system by its ability to detect gas plumes as a function of the emission rate of those plumes. It does so through a generalised probability of detection function that expresses detection probability relative to emission rate as a function of gas concentration noise and gas flow speed, the two variables that most directly govern whether a given plume clears the threshold.

That function then supports two applications the specification describes. First, it can be used to estimate the cumulative distribution of gas plumes that were not detected, working from the cumulative distribution of the plumes that were measured. In other words, the shape of what you found, combined with a calibrated understanding of what you would have missed, lets you infer the missing tail. Second, the same function can be used to refine an estimate of a measured emission rate, improving the accuracy of the numbers the survey does report.

The approach turns a survey result from a list of detections into a statistical estimate of total emissions, with its uncertainty characterised rather than assumed away.

Key Features

• Emission rate characterisation. The measurement system is characterised by detection ability as a function of plume emission rate.
• Generalised probability of detection function. Detection probability is expressed relative to emission rate in a generalised form.
• Concentration noise dependence. Gas concentration noise is an explicit input to the detection probability function.
• Flow speed dependence. Gas flow speed is the second explicit variable governing detection.
• Undetected plume estimation. The cumulative distribution of undetected plumes is estimated from the distribution of measured plumes.
• Emission rate refinement. The same function is used to refine estimates of measured emission rates.

Who Is Behind It

The applicant is Bridger Photonics, Inc., an American photonics and remote sensing company headquartered in Bozeman, Montana, whose Gas Mapping LiDAR system launched commercially in 2019 and provides emissions mapping services to oil and gas operators. The named inventors are Michael James Thorpe and Aaron Thomas Kreitinger. The application is a divisional of Australian application 2022431237 and claims priority from a United States provisional filed in January 2022. The specification records that the work was supported by the United States Department of Energy under an award administered through ARPA-E, which retains certain rights in the invention.

Why It Matters

Methane is a far more potent greenhouse gas than carbon dioxide over short timescales, and cutting leaks from oil and gas infrastructure is one of the more tractable near-term climate actions available. That has made measurement a regulatory issue as well as a technical one, with programs such as the International Methane Emissions Observatory and national reporting rules increasingly requiring operators to quantify emissions rather than estimate them from generic factors.

Once measurement carries regulatory and financial consequences, the quality of the measurement claim matters as much as the measurement. A survey reporting detections without characterising its own detection limits invites the obvious objection that it simply did not look hard enough. Formalising probability of detection as a function of emission rate, noise and flow speed makes the missing tail estimable and the reported figure auditable. That is unglamorous statistical work, and it is the kind of thing that determines whether remote sensing data can carry weight in a compliance regime or remains a screening tool.

Related Concepts

• Methane emissions – the environmental problem these surveys measure.
• Lidar – the remote sensing technology behind gas mapping systems.
• Laser absorption spectrometry – the measurement principle used to detect gas concentration remotely.
• Cumulative distribution function – the statistical object used to estimate undetected plumes.
• Remote sensing – the wider field this instrument belongs to.
• ARPA-E – the United States agency that funded the underlying research.

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AU 2026202062 was published in the Australian Official Journal of Patents on 9 April 2026 and is open for public inspection. Patent applications represent inventions that are sought to be protected and do not necessarily reflect commercially available products.