text: Social impact The oil and gas industry spends only 0.4% of its net sales on research & development (R&D) which is in comparison with a range of other industries the lowest share. Governments such as the United States government provide a heavy public subsidy to petroleum companies, with major tax breaks at various stages of oil exploration and extraction, including the costs of oil field leases and drilling equipment. In recent years, enhanced oil recovery techniques – most notably multi-stage drilling and hydraulic fracturing ("fracking") – have moved to the forefront of the industry as this new technology plays a crucial and controversial role in new methods of oil extraction.
  Environmental impact
  Water pollution
  Some petroleum industry operations have been responsible for water pollution through by-products of refining and oil spills. Though hydraulic fracturing has significantly increased natural gas extraction, there is some belief and evidence to support that consumable water has seen increased in methane contamination due to this gas extraction. Leaks from underground tanks and abandoned refineries may also contaminate groundwater in surrounding areas. Hydrocarbons that comprise refined petroleum are resistant to biodegradation and have been found to remain present in contaminated soils for years. To hasten this process, bioremediation of petroleum hydrocarbon pollutants is often employed by means of aerobic degradation. More recently, other bioremediative methods have been explored such as phytoremediation and thermal remediation.