Nigel Snelling obtained a Business Studies degree from Norwich City College in the UK in 1974, a professional certification in Purchasing and Materials Management from the UK Institute of Purchasing & Supply in 1977, and an MBA from the Open University in the UK in 1998.

Snelling joined Marathon Oil Company in June 1981 as a purchasing agent in the European Supply & Marine Transportation group in London. In March 1984, he transferred to the London Internal Auditing group and was appointed Audit Supervisor in London in March 1988, Financial Operations Supervisor in October 1989, and Budget Supervisor in April 1991. In April 1992, Nigel was appointed UK Audit Manager. During 1994, he transferred the Internal Auditing function from London to Aberdeen, Scotland, and relocated to Aberdeen in January 1995.

In November 1998, Nigel was appointed Marathon Oil Company Audit Manager in Findlay, Ohio. In January 2002, he became Marathon Ashland Petroleum LLC Audit Manager. In October 2005, he moved to Business Development where he was involved in developing biofuels opportunities and strategies for Marathon, including equity positions in two corn-based ethanol plants and an investment in a cellulosic ethanol start-up company. In July 2011, following the split of Marathon Oil Company into two independently-traded companies, a new Biofuels and Emerging Technology group was formed and Snelling serves in this group as Manager, Commercial Development. The group is charged with screening investment and supply agreement opportunities involving new technologies that could produce biomass-based refinery feedstocks or terminal blendstocks, as well as evaluating renewable power generation opportunities, such as wind or solar.