Methane venting from uncontrolled production storage tanks at conventional oil wells: Temporal variability, root causes, and implications for measurement 

Emissions from uncontrolled oil production storage tanks are poorly understood and characterized. This study reports and analyzes directly measured, temporally varying methane emission rates, total gas vent rates, and vent gas methane fractions from storage tanks at eight active upstream oil production sites in Alberta, Canada. Detailed statistical analyses were completed to suggest minimum sampling durations and instrumentation requirements for direct measurements of tanks and minimum sample sizes for discrete (“snapshot”) surveys of both individual tanks and multitank surveys under different scenarios. Results show that caution is warranted when interpreting snapshot measurements of individual tanks, but aggregate emissions of multiple tanks should be accurately measurable with readily achievable sample sizes.