Nigeria

Chevron is the world's fifth largest global energy company and engages in oil exploration and production; refining, marketing and transport; chemicals manufacturing and sales; and power generation. The company is currently embroiled in major lawsuits for the contamination of Ecuador (Aguinda v. Chevron) and alleged crimes in Nigeria (Bowoto v. Chevron).

Halliburton is a leader in the oil services industry -- i.e. provides engineering and construction services for oil extraction and development. After separating from Kellogg, Brown & Root (KBR) in 2007, it is no longer in the business of providing military logistics support.