North Dakota recently passed legislation with strict oil treatment requirements. The government in Saskatchewan has said they will be inspecting wells and sites this year to ensure proper treatment.
by Sheldon McKee
August 17, 2015

The continued expansion and production in the Canadian oil sands provides benefits for both industry and consumers. But it also poses a growing number of health and safety concerns. The steam-assisted gravity drainage (SAGD) process used at some oil sands sites can lead to high amounts of sour gas, or hydrogen sulphide (H2S), during exploration and production.

Most Alberta oil sands contain H2S, presenting a major challenge to producers operating in this area for the equipment, environment and, most important, the safety of the operators. H2S is dangerous and must be handled and treated properly.

The risks associated with H2S are severe depending on its concentration. Health effects range from nausea and headaches at an exposure of 200-300 parts per million (ppm) to death starting at an exposure of 300 ppm. H2S emissions are a concern in any oil extraction application, but the risk is becoming increasingly visible at the oil sands. Recent exposures in Saskatchewan have resulted in the deaths of animals and humans and have spurred new emissions regulations.

H2S is typically viewed as the most dangerous substance that could break out of sour oil. It is toxic in high concentrations, flammable and corrosive, with the potential to cause both safety and operational issues downstream of the liquid. A number of harmful emissions are produced in extraction, and they all must be treated before exposure happens. Mitigating the risks of harmful emissions must be a top priority for oil sands producers to keep their sites safe.

Shutdowns & Turnarounds

Oil sand facilities are at an extremely high risk for H2S exposure during shutdowns and turnarounds. When preparing for maintenance, cleaning or inspection, many elements at the site are adjusted or removed, greatly increasing the risk of H2S escape and exposure. Sufficient venting, seals and training are required. New information on the dangers of benzene, toluene, ethybenzene and xylenes (BTEX), and hydrocarbon exposure to workers' long-term and short-term health has become available. BTEX and other volatile organic compounds (VOC) are almost always present in turnaround operations and are even more common than H2S.

Figure 1. Options for removing H<sub>2</sub>S (Images and graphics courtesy of AMGAS)Figure 1. Options for removing H2S (Images and graphics courtesy of AMGAS)

Production in oil sands often requires treatment of sour water for reuse. With dramatic increases in unconventional shale and oil sands production across Canada, access to freshwater is becoming more and more restricted. Treating sour water that is intended for reuse in place of freshwater requires a chemical-free process. One company's process can reduce disposal and operational costs by 50 percent.

Sour fluids and vapors present during shutdowns and turnarounds lead to escalating costs and increased downtime. Since prolonged downtime is a risk for producers, variable H2S conditions in fluid handling and transportation operations pose a significant risk. Regulations and laws are beginning to come into effect across many production-heavy regions. North Dakota recently passed legislation with strict oil treatment requirements. The government in Saskatchewan has said they will be inspecting wells and sites this year to ensure proper treatment.

Flaring is an H2S treatment process popular among producers outside of Canada, but it is also controversial. Its use is declining because of sulphur dioxide (SO2) and carbon dioxide (CO2) emissions and other environmental concerns. Furthermore, not all sour gas present is burned off through the flaring process.

Image 1. Production in oil sands often requires treatment of sour water for reuse.Image 1. Production in oil sands often requires treatment of sour water for reuse.

It is much more common and efficient for H2S to be treated at the extraction site. While many companies are offering producers chemical processes to treat H2S at their sites, some alternative options appeal to a growing number of producers. Chemical-free alternatives seem to be moving the oil industry forward.

Industry Impact

Sour gas will likely become increasingly important in future oil sands operations. Government regulations will probably increase, and efficient H2S removal will be necessary.

Removal is important for all involved parties—producers, regulators and consumers. Environmental, health and safety concerns will affect how the industry proceeds and responds to public concern and demand.