Banpu Pcl, Thailand's largest coal miner, said on April 20 it had spent $112 million to buy a 29.4% stake in the Chaffee Corners Joint Exploration Agreement (JEA), a shale gas operation in Pennsylvania.

The Thai company said in a statement the deal was its first in the U.S. upstream gas business and was part of its strategy to balance its heavy exposure to the Asian market.

JEA is 65.4% owned and operated by Talisman Energy Inc. and located in the northeast section of the Marcellus Shale belt, the largest source of natural gas in the U.S., it said.

Banpu's investment represents proved reserves of 156 billion cubic feet (Bcf) of dry natural gas and target net output of around 21 MMcf/d for 2016, the company said.

The gas is sold entirely to the U.S. domestic market, mainly for power generation.

Many energy firms have been forced to write down the value of their U.S. shale gas operations due to the slump in oil and gas prices.

Banpu said it had appointed Anon Sirisaengtaksin, the former chief executive of PTT Exploration and Production Pcl, Thailand's largest oil and gas explorer, as a director and to advise on its upstream gas strategy.

The Thai company has sought to diversify into the power business to help balance the impact of weak coal prices. Banpu aims to boost its power generating capacity to 4,300 megawatts by 2025, including 800 megawatts of renewables.

Banpu has coal mines in Indonesia, Australia, and China and has interests in power plants in Laos, China and Japan.