(224m) Impact of Fugitive Emissions on the Greenhouse Gas Emissions of Conventional Crudes

Fugitive emissions are unintended gases released to the atmosphere that can come from a variety of sources.  These sources included equipment leaks, process venting, evaporation losses, venting, flaring, accidents and equipment failures.  By nature they are variable because they depend on controlled and uncontrolled parameters that are specific to a particular process, which makes their estimation difficult. This study quantifies the fugitive emissions from ten different oil fields across the world to evaluate their impact on the well-to-wheel (WTW) greenhouse gas (GHG) emissions. Previous studies on these reservoirs either used an estimation of the associated gas loss at 0.5% or didn’t consider them at all. To estimate fugitives, it was assumed a portion of the associated gas from the crude oil is lost to the atmosphere. The percentage gas loss was estimated from previous studies that determined the portion of natural gas released as fugitive emissions from oil and natural gas fields. The associated gas amount for each oil field varies as seen by the gas-to-oil ratio (GOR), which range from 366 scf/bbl-crude to 12,218 scf/bbl-crude for the Maya and Alaska North Slope oil fields respectively. Fugitive gas amounts were found by multiplying by the percentage of methane in the gas (specific to each location), which was converted to carbon dioxide equivalents to give the GHG emissions. These fugitive emissions were added to previous work by this group that calculated the WTW GHG emissions of these reservoirs. Results show that fugitive emissions increase with increasing GOR. For reservoirs with a high GOR, emissions are not negligible and should be considered in the life-cycle assessments of these conventional crudes. The sensitivity analysis indicates that the fugitive GHG emissions increase by 50% with just a one percent increase in the percentage of associated gas lost.