QUITO, June 7 (Reuters) - Ecuador's government expects crude output to hit 480,000 barrels per day (bpd) and to sign contracts with energy companies during President Guillermo Lasso's last months in office, energy minister Fernando Santos said on Wednesday.

Conservative ex-banker Lasso has ruled by decree since mid-May, when he used a constitutional quirk to dissolve the National Assembly and bring forward presidential and legislative elections, shortening his term, which was due to end in 2025.

Ecuadoreans will vote on a replacement for Lasso, who will not run in the elections, on Aug. 20.

"(Crude) production will remain around 480,000 bpd," Santos said in an interview, adding output is tricky due to the longevity of the Ecuador's oil fields. "These are fields that have already been in production for 50 years."

Ecuador is currently producing around 470,000 bpd according to the government.

Lasso had promised to double Ecuador's oil output during his term but could not deliver progress on the goal due to problems with production and attracting private investment.

The government has reached a deal with Chinese oil company Andes Petroleum to extend a contract, due to expire in 2025, by 15 years, Santos said.

The company will invest some $200 million to increase its production, which is now around 24,000 bpd, he added.

Ecuador is also renegotiating its contract with Chile's Enap, Santos said.

The contract expires in 2035, but a new deal could see the company increase investment by $100 million to boost production in exchange for a special rate on royalties per barrel.

The government expects to sign contracts for four exploration blocks in August and will also receive offers to construct a high-conversion plant at the largest Esmeraldas refinery, Santos said.

"We'll do as much as we can," Santos said, adding the administration will discuss potential contracts for the Esmeraldas refinery with the new government.

The investment for the refinery could be around $2 billion, Santos said. (Reporting by Alexandra Valencia Writing by Oliver Griffin; editing by Grant McCool)