EPA's recent draft inventory of greenhouse gas emissions (1990 - 2015) showed methane emissions from natural gas systems are down 18.6 percent since 1990, and emissions from petroleum systems are down 28.8 percent — without these recent regulations. (energytomorrow.org)
«Such information may not only be relevant for atmospheric methane budget studies but may also be important for understanding the leaking potential of petroleum systems, whether they are commercial or not.» (sciencedaily.com)
In their 2005 paper Indications for an active petroleum system in the Laptev Sea, NE Siberia, Cramer and Franke (CF5) presented seismic data and analyses of gas samples that showed that there are deep sedimentary basins in this part of the Arctic Ocean that are actively seeping fossil methane. (critical-angle.net)