This annual survey of global energy companies by S&P Global Commodity Insights measures companies' financial performance using four key metrics: asset worth, revenues, profits, and return on invested capital.

All companies on the list have assets greater than US $5.5 billion. The fundamental and market data comes from a database compiled and maintained by S&P Global Market Intelligence.

Energy companies were grouped according to their Global Industry Classification Standard (GICS) code. Each company is assigned to an industry according to the definition of its principal business activity.

Because the survey is global, and because all countries do not share a common financial reporting standard, the information presented is for each company's most current reporting period. Since then, material changes to a company's financial health may have occurred. Data for U.S. companies came from Securities and Exchange Commission (SEC) Form 10K.

The company rankings are derived using a special S&P Global Commodity Insights formula. We added each company's numerical ranking for asset worth, revenues, profits, and ROIC and assigned a rank of 1 to the company with the lowest total, 2 to the company with the second-lowest total, and so on.

Finally, ROIC figures-widely regarded as a driver of cash flow and value-were calculated using the following equation: ROIC = [(Income before extraordinary items) - (Available for common stock)] ÷ (Total invested capital) x 100 where "Income before extraordinary items" is net income less preferred dividends and "Total invested capital" is the sum of total debt, preferred stock (value), noncontrolling interest, and total common equity.