BreitBurn Energy Partners has signed a definitive agreement with an undisclosed seller to acquire natural gas and oil assets in Wyoming, US, for $285m in cash.

The assets are located in the Evanston and Green River Basins of Southwest Wyoming and are 95% natural gas.

The acquisition includes estimated proved reserves of approximately 230 billion cubic feet equivalent, with 136 billion cubic feet equivalent of estimated proved developed producing reserves.

BreitBurn Energy expects to produce more than 30 million cubic feet equivalent per day from these assets in 2012.

BreitBurn Energy Partners CEO Hal Washburn said that the assets will provide years of production growth through a significant inventory of low risk development opportunities and will enhance the firm’s exposure to natural gas.