The decision on the Environmental Assessments for the experimental projects proposed by Chevron, EGL Resources and Shell Frontier Oil&Gas paves the way for the companies to pick up the 160-acre leases for the projects in the Green River formation.

The formation is thought to hold about 800 billion barrels of oil in Colorado alone.

The Bureau of Land Management has drafted 10-year lease agreements for the two supermajors and US-based EGL Resources to review, a spokeswoman with the BLM said.

The