The following definitions reflect those used by the
International Energy Agency (IEA); definitions used by other
organisations and publications may vary. operation and
maintenance open-cycle gas turbine oxidative coupling of methane
official development assistance outward direct investment
original equipment manufacturer Online Information System, an
OECD/IEA system for submitting official documents for OECD and
IEA committees, standing groups and working parties other major
economies Oil Market Report (IEA publication) organic Rankine
cycle ocean thermal energy conversion the production decline
rate of an oil or gas field after all measures have been taken
to maximise production. It is the aggregation of all the
production increases and declines of new and mature oil or gas
fields in a particular region. includes crude oil, condensates,
natural gas liquids, refinery feedstocks and additives, other
hydrocarbons (including emulsified oils, synthetic crude oil,
mineral oils extracted from bituminous minerals su