May 31 (Reuters) - U.S. pipeline operator Kinder Morgan Inc said on Wednesday it plans to expand the working gas storage capacity at its Markham facility in Matagorda County, Texas, by 6 billion cubic feet (Bcf).

The decision comes after Kinder Morgan earned about $1 billion during February's U.S. winter blast as heating demand pushed natural gas prices to record highs.

The company will lease an extra cavern at the facility, which will provide an additional 650 million cubic feet per day of withdrawal capacity on its Texas intrastate pipeline system, along with more storage capacity.

Before the expansion, the Markham facility had 21.8 Bcf of working gas storage capacity.

(Reporting by Ankit Kumar; Editing by Devika Syamnath)