Kuwait National Petroleum Co. borrowed $6.2 billion in May for a refinery and clean fuels projects. Saudi Arabian Oil Co. sold $3 billion in Sharia-compliant bonds in April. Adnoc's fuel retailing unit took out a loan and revolving credit facility totaling $2.25 billion in November before its initial public offering this month. Saudi Aramco, as the state energy producer is known, has a $2 billion loan guarantee from the U.K. government in the run-up to its proposed IPO next year, likely to be the largest in history. Further debt may be issued next year to finance power plants in Saudi Arabia and petrochemicals in the region, Mills said. Over the next decade, Saudi Aramco will invest $300 billion to maintain its spare oil-production capacity and explore for natural gas, President and CEO Amin Nasser said in July.