Oil and gas production from many fields contains some amount of hydrogen sulfide (H₂S), a poisonous, acidic gas that must be sequestered to avoid damage to downstream equipment and risks to human health.

Concentrations of H₂S in the production stream can vary from below 50 parts-per-million (ppm) to more than 100,000 ppm (10% of the total stream).

In the Permian Basin, for example, Xia and He report that over 85% of gas streams contain more than 100ppm of H₂S, while over 40% are considered extremely H₂S rich (>1%).

Thankfully, a significant proportion of wells experiencing H₂S contamination fall somewhere on the lower side, below ~1,000 ppm.

Removing such moderate amounts of hydrogen sulfide from produced gas doesn’t need to be complicated.

Approaches to Removing H₂S

Large-scale H₂S removal typically uses some form of adsorption, a process that is economically and energetically favorable across a wide range of concentrations and temperatures.

Where the H₂S concentration doesn’t warrant a fully-fledged regenerative adsorption system, treatment with a liquid chemical is often used to sequester the H₂S.

Nevertheless, this still requires some form of mixer or contact tower, pumps, liquid storage, and disposal of the spent chemicals.

Finally, a dry scavenger system with the latest generation of solid media can be used.  This requires only a single treatment vessel in which the scavenger (iron oxide) adsorbs all hydrogen sulfide present in the gas as it passes through.

Issues With Liquid Scavengers

The amount of liquid scavenger mixed into the production stream must be sufficient to completely treat the H₂S present.

Insufficient treatment can lead to equipment failure due to corrosion and the hazardous discharge of untreated H₂S.

Since H₂S levels fluctuate along with other well performance parameters, over-treatment is commonplace to mitigate any spikes in H₂S concentration.

This can result in scaling and fouling downstream of the production facility due to excessive amounts of scavenger in the production stream.

From a cost perspective, installing and maintaining the system can have a significant impact on lease operating expense.

The Advantages of Dry Absorption

In contrast, a dry scavenger system adsorbs all the hydrogen sulfide present, without the need to over-treat for spikes or maximum expected concentrations.

This eliminates the risk of any downstream scaling or fouling.

The dry scavenger is easy to replace since it does not solidify or need to be separated from the flow stream and stored.

Cumulative sulfur loading can be monitored using test ports, either manually or automatically, and media changeout planned in a timely manner.

The system is also straightforward and low-cost to maintain.

One operator in Colorado reported reducing direct H₂S mitigation costs by 75% – over $10,000 per week – in large part due to the elimination of over-treating with triazine.

They also achieved significant uptime improvement on downstream equipment, commenting that “operators no longer have to spend time managing [H₂S] treatment.”

The Sulfur Sentinel by EcoVapor

EcoVapor’s full package solution includes designing the vessel based on actual site conditions, installation, monitoring, scavenger changes as required, and disposal of the non-hazardous spent media.

Contact us at info@ecovaporrs.com for further information.