Finding What’s Left Behind: Lessons from the Field in Methane Detection

What happens when a methane leak starts from a well drilled over a century ago, and no one knows it’s there?

It’s not a riddle. It’s a real and growing challenge for oil and gas operators and regulators. Across the country, aging infrastructure and improperly abandoned wells can become hotbeds for methane leaks—some so serious they’ve led to explosions. The risks are underground, invisible, and incredibly difficult to trace using traditional detection methods.

At Montrose, we’re tackling this problem head-on with a field-driven, multi-technology approach—combining drones, mobile sensors, hydrogeological analysis, and cameras—to locate and quantify emissions at legacy sites.

In this blog, we share what we’re learning as we pilot new methane detection solutions on the ground and in the air.

Legacy Emissions: When History Becomes a Hazard

Long before environmental regulations, oil and gas development left poorly documented wells and pipelines behind. Fast-forward a century, and some of these forgotten assets have degraded and are now emitting methane in hard-to-detect ways—posing environmental, operational, and public safety risks.

One project focused on these hidden emissions. Using a drone equipped with a thermal payload, Montrose teams scanned known and suspected sites at pre-dawn hours—when ambient conditions are most favorable for detecting subtle upwelling of methane.

A drone-mounted thermal camera detects methane-rich groundwater upwelling in a pond from underground sources—alongside visible thermal trails from nearby ducks.

Eye in the Sky, Boots on the Ground: Matching Detections with Verification

Drone visual detections are a great start—but they don’t close the loop on their own.

To confirm aerial observations, Montrose deployed a Purway payload drone alongside a mobile methane CEMS mounted on a truck to quantify the methane sources. The drone provided wide-area coverage, while the truck traced ground-level concentrations along roadways and access paths.

A drone with methane detection payload in flight over a survey site.

Montrose’s mobile CEMS system in action, collecting near-surface methane concentration data.

A map showing elevated methane readings collected by the mobile sensor during a confirmation sweep.

When the Leak Is in the Engine: Tackling Methane Slip from Compressors

Not all methane comes from broken equipment. Some of it comes from engines doing exactly what they’re designed to do. Incomplete combustion is a large source of methane emissions.

As part of a BC-funded research initiative, Montrose is working with the BC Oil and Gas Research and Innovation Society (BC OGRIS) and Methane Emissions Research Collaborative (MERC) to study methane slip emissions from natural gas compressors. The project compares high-cost and low-cost monitoring solutions across different engine makes, models, and horsepower levels.

A test setup used to evaluate exhaust methane emissions.

These studies are shaping the region’s strategy for scalable, cost-conscious emissions monitoring.

Not Just Detecting—Capturing and Quantifying Tank Emissions

Vents are another major—and often underestimated—source of methane emissions. To address this, Montrose developed a proprietary total capture device that safely routes all vented gas into a high-flow sampler.

The total capture system deployed at a tank vent, allowing for safe, comprehensive quantification.

This level of resolution is essential for accurately assessing site-level contributions.

Making the Data Useful: Sensible EDP and Platform Integration

Detection is just the beginning. Making methane data actionable requires platforms that can ingest, interpret, and visualize information from a growing list of tools and technologies.

Montrose’s Sensible EDP software platform connects data from partners like Kuva, Qube, SeekOps, GHGSat, Nevada Nano, and SLB—creating a unified view that supports field teams, analysts, and compliance staff alike.

“Montrose’s software solution enables enhanced operational monitoring and the ability to reduce alarm fatigue through clearer data visualization and interpretation.”

By reducing noise and improving clarity, platforms like Sensible help prioritize action and elevate decision-making.

What We’re Learning in the Field

Every legacy site brings unique challenges, but a few takeaways have proven universal:

• Pairing detection technologies (like drones and CEMS) improves accuracy and speeds up leak verification.
• Cost-effective tools can be powerful when deployed thoughtfully and combined with skilled field teams.
• Data must be integrated—otherwise, insights stay siloed and opportunities get missed.

These projects continue to provide invaluable feedback on where technology excels and where collaboration is still needed.

Final Thoughts: A Field-Led Future for Methane Detection

The emissions landscape is changing—and so is the way we monitor it.

Whether it’s tracing a plume from a long-abandoned well or quantifying flow from an active tank vent, the job of measuring methane is no longer about relying on one tool. It’s about understanding how different technologies, deployed together, can close data gaps and inform better decisions.

As regulations evolve and expectations rise, the role of field-validated, multi-tech approaches will only grow. We’re learning more with every deployment—and the results speak for themselves.

Ready to Tackle Legacy Methane Emissions at Your Site?

Whether you’re dealing with aging infrastructure, regulatory pressure, or the unknowns of abandoned assets, Montrose is here to help. Our team brings proven field experience, multi-tech solutions, and actionable insights to every project.
Contact us today to discuss how we can support your methane detection, quantification, and compliance goals.