An environmental advisor replaces a filter at this passive air monitoring station at Long Lake.

Working to Reduce Emissions

Through investments in technology, we’re working to ensure the oil and gas products we generate are produced in a manner that meets, or exceeds, the regulatory requirements that preserve regional air quality. For example, our Long Lake Oil Sands facility in northern Alberta, Canada, features state-of-the-art sulphur recovery equipment, enabling the capture of at least 98.4% of the inlet sulphur to the plant, which is the regulatory requirement.

Our shale gas operation in northeast British Columbia, Canada, uses “reduced emission completions” (known as RECs or green completions) for our hydraulically fractured development wells at our Dilly Creek site. All of the natural gas produced during and after the wells are completed is conserved, compressed and then sold. This process, which is not yet common practice in other jurisdictions, virtually eliminates all emissions associated with venting or flaring the flow-back gas from hydraulically fractured wells.

Figure 1 shows the process that is typically used for flow-backs from hydraulically fractured wells. The flow-back fluids are passed through a sand trap to remove sand from the produced fluid. The stream then passes through a separator to separate the gas and water phases. The gas is metered and then flared and the water is metered and directed to a storage tank. Dissolved gas in the water is released and vented when the flow-back water enters the storage tank.

Figure 1. Typical completions process (acceptable in some jurisdictions) 

In contrast, for Reduced Emission Completions (Figure 2) most of the emission sources are eliminated. After separation of the gas and liquid phases, the two streams are recombined and pipelined to a processing facility. At the processing facility, the gas and liquid are separated again. The gas is dehydrated, compressed and sent to market. The liquid is temporarily stored in tanks equipped with emission controls to minimize emissions prior to injection into a disposal well.

Figure 2. Reduced emissions completions process (used by Nexen operations)

Reduced Emission Completions result in GHG emission reductions of 90 to 95% compared to the alternative process.

In our shale gas operations, we also continue to use a bi-fuel system to offset some of the diesel fuel consumed by drilling rigs with cleaner burning natural gas, thereby reducing emissions of oxides of nitrogen (NOx), sulphur dioxide (SO2), volatile organic compounds (VOC) and particulate matter (PM). We utilize this process at our completions frac units at Dilly Creek.

Partnering on Air Quality Monitoring

Nexen is one of the industry partners that support the work of the Wood Buffalo Environmental Association (WBEA), which monitors air quality throughout the Regional Municipality of Wood Buffalo – one of the largest municipalities in North America and home to the oil sands industry. WBEA maintains 15 fixed and two mobile ambient air quality monitoring stations throughout the region and provides ambient air quality data and an air quality index that are updated hourly. These data are made available to the public through the WBEA website 24 hours a day, 365 days a year.

In addition to the air quality monitoring station that is located in the community of Anzac – the closest community to our Long Lake oil sands facility, we must also collect air quality monitoring data through 12 passive air monitors. Air quality data from the Anzac station is fed on a real-time basis to Alberta Environment and WBEA. This data is available on the WBEA website.

In 2013, a Joint Canada-Alberta Implementation Plan for Oil Sands Monitoring was put in place and is funded by industry, including Nexen. The plan aims to provide world class monitoring of air, water and biodiversity for the oil sands region of Alberta. The intent is not to replace the air monitoring programs currently managed by WBEA, but rather to enhance and improve the scope and coverage of the programs.

Nexen has operations in other areas of Canada and we are committed to supporting the airshed societies in those areas. We are members of the Calgary Region Airshed Zone (which includes our Balzac Power Station) and the Palliser Airshed Society (which includes our Medicine Hat operations). We will participate in the northeast British Columbia airshed society when it begins operation.