Using growth and decline factors to project VOC emissions from oil and gas production

Projecting future-year emission inventories in the oil and gas sector is complicated by the fact that there is a life cycle to the amount of production from individual wells and thus from well fields in aggregate. Here we present a method to account for that fact in support of regulatory policy development. This approach also has application to air quality modeling inventories by adding a second tier of refinement to the projection methodology. Currently, modeling studies account for the future decrease in emissions due to new regulations based on the year those regulations are scheduled to take effect. The addition of a year-by-year accounting of production decline provides a more accurate picture of emissions from older, uncontrolled sources. This proof of concept approach is focused solely on oil production; however, it could be used for the activity and components of natural gas production to compile a complete inventory for a given area.

Implications: The Uinta Basin has unique atmospheric chemistry regimes during the winter that create ozone concentrations far exceeding those in the largest U.S. cities. This is also an area of complex regulatory authority shared among state, tribal, and federal agencies. This research accounts for regulations that are currently being implemented, and ties the effect of those regulations to emission factors used to estimate future-year inventories. This approach holds promise for future-year projections of oil and gas inventories for the region by providing a more representative life cycle of oil and gas emissions, including the disproportionate impact of older, uncontrolled sources.