GEORGETOWN (Reuters) - U.S. oil major Exxon Mobil ( XOM ) is planning to increase natural gas output and supply in Guyana through a large-scale project announced on Wednesday, following the government's call for more gas to fuel onshore power and petrochemical projects.

The "Wales Gas Vision", outlined by Exxon's Guyana head, Alistair Routledge, is set to provide gas for the production of fertilizers through a $1 billion pipeline completed last year.

The government will take a portion of the gas supplied by Exxon for power generation and natural gas liquids production through its Gas-to-Energy project.

Exxon's Wales project also requires the building of separate pipelines and a gas processing and liquefied natural gas (LNG) offshore facility. The facility will allow LNG exports and gas supply to Guyana's Berbice area for producing fertilizers and alumina, Exxon said.

The company did not give a total investment figure for the project.

The Exxon-led consortium in Guyana, in which U.S. Hess and China's CNOOC participate, plans to ramp up gas output in the coming years, especially through projects involving gas not associated with oil, such as Longtail.

A final investment decision for Longtail, which would be the group's eighth project in the South American country and deliver up to 1.2 billion cubic feet per day (bcfd) of gas, is expected next year.

Exxon is "ready to deliver gas" to shore, Routledge said at Guyana's Energy Conference.

Guyana is aiming to add natural gas to an energy mix dominated by oil output, helping to increase power generation and open new sources of revenue by exporting petrochemicals and LNG, energy minister Vickram Bharrat said earlier on Wednesday.

"There will be a shift towards gas utilization and monetization", the minister said at the conference in Georgetown. The government is expected to launch its ambitious gas strategy this year.

The country's fourth floating oil production facility, built by SBM Offshore that departed from Singapore this week, will start operations in the third quarter, Exxon said.