Microseepage of C2–C5 alkanes over the Baldwin Hills in Los Angeles

Microseepage of C2–C5 alkanes from subsurface natural gas and oil reserves was quantified over the Inglewood oil reserve in southern California. Flux measurements were carried out in 2011 and 2012 using chamber samples. Direct positive fluxes were observed for ethane and propane. Observed fluxes collected above known fault zones were no greater than those collected outside of fault zones. The highest observed fluxes were of ethane (65.8 μg m−2 h−1) and propane (88.0 μg m−2 h−1). The average flux values of all samples collected were 0.9 μg m−2 h−1 for ethane and 0.5 μg m−2 h−1 for propane.