Oil union workers filed a suit against the operation in the northeastern state of Sergipe last year, claiming Petrobras had breached competition and transparency rules.
Traditionally, state-run banks have assumed a key role in infrastructure financing, but the private sector may participate more actively in this sector, according to speakers at the Brazil Investment Forum.
The two countries are set to create a fund of up to US$20bn mostly to finance infrastructure projects.
Petrobras refused to sell natural gas to the plant's operator, Eletrobras, over a multibillion-dollar debt related to unpaid fuel bills.
The NOC will supply Colbún's Nehuenco combined-cycle plant for 12 years starting 2019.
Lower house lawmakers have filed several impeachment requests and the country's bar association will join the efforts to remove the president from the office.