* Petrobras announced $236.7 bln 5-yr investment plan Friday
* Plans to double Brazil's natural gas supply by 2020
* Texas refinery pulled from shrinking asset-sale plan
RIO DE JANEIRO, March 19 (Reuters) - Brazil's state-run oil company Petroleo Brasileiro SA and its board of directors are committed to maintaining their investment-grade debt rating and not selling new stock, executives told investors on a conference call Tuesday.
While the company's debt has passed Petrobras' internal limit of 2.5 times earnings before interest, taxes, depreciation and amortization (EBITDA), that ratio is expected to fall below the limit by sometime in 2014, Chief Financial Officer Almir Barbassa said.
The conference call detailed Petrobras' $236.7 billion five-year investment plan announced on Friday. Under the plan, the world's largest corporate investment program, Petrobras increased spending in exploration and production by 4 percent but cut funding for biofuels and new refineries as it focuses on increasing oil and natural gas output.
New oil production is needed to generate cash to lower the company's debt. Though Petrobras does not foresee a stock sale, it expects annual bond sales of $12 billion under its new investment plan, compared with $20 billion last year, Barbassa said. He said a plan to reduce costs on Petrobras oil wells could save at least $1.4 billion.
Petrobras is also selling some assets to try to raise cash, but Chief Executive Officer Maria das Graças Foster said Petrobras' Pasadena refinery in Texas would no longer be included in asset sales.
Though Foster did not say why the refinery would be excluded, some have said the company paid too much for it. There was also an investigation into Petrobras' handling of the refinery by Brazil's national public accounts auditing tribunal.
In its previous five-year plan, announced last year, Petrobras had hoped to sell about $15 billion of assets to help finance expansion. As it rushed to sell assets, the company found potential buyers reluctant to pay top dollar for projects such as its oil leases in the Gulf of Mexico.
The company now expects to sell $9.9 billion of assets by the end of 2017.
Petrobras also plans to double the supply of gas to the Brazilian market by 2020 and double the capacity of liquefied natural gas (LNG) import terminals in the same period. It expects domestic demand for fuels in Brazil to grow an average 4.2 percent per year until 2020.
Petrobras preferred shares fell 0.68 percent in Sao Paulo trading on Tuesday.