Petrobras' Block 31 project will be constructed in an area identified by Conservation International as one of the largest contiguous tracts of the most biodiverse intact wilderness in the world. Further research has concluded that the forests of Yasuni are probably the most diverse in the world. Yasuni has been declared by WWF Scientists as among the most important ecoregions globally to protect.

The development's environmental assessment states "the possibility of a catastrophic [oil] spill cannot be ruled out" at the processing plant, and that there is "probable" risk that indigenous communities affected by the project will engage in physical protests and interventions that could lead to work stoppages and violence.

Introducing the two oil platforms, associated infrastructure and personnel into the region will cause such broad and direct secondary environmental and social impacts that 43 concerned scientists from Ecuador, the United States and Europe wrote to the President of and its Environment Minister concerning the most recent development proposal (plans have been altered and long delays have occurred) recommending that no new drilling be undertaken in Yasuni. The letter informs that regardless of the drilling method used impacts of the existing plan, the lack of full consultation and informed consent of significant elements of the indigenous population affected outweigh all indications that the project should proceed.

The inadequate environmental assessment and likely risks have lead to apparent violations of the Equator Principles, including Principle 3, Applicable Social and Environmental Standards; Principle 5, Consultation and Disclosure; Principle 6, Grievance Mechanism; Principle 7, Independent Review. An elaboration of these violations can be found in the Investors’ Briefing.