id	keyword
american_scientific_journal-3254	gas
american_scientific_journal-3254	hydrate
american_scientific_journal-3254	methane
american_scientific_journal-3254	cost
american_scientific_journal-3254	production
american_scientific_journal-3254	energy
american_scientific_journal-3254	volume
american_scientific_journal-3254	nea
american_scientific_journal-3254	time
american_scientific_journal-3254	methane hydrate
american_scientific_journal-3254	research
american_scientific_journal-3254	oil
american_scientific_journal-3254	technology
american_scientific_journal-3254	countries