Polish energy company PGNiG announced it signed an agreement with a Chevron subsidiary to explore for shale natural gas in southeastern Poland. PGNiG, the Polish initials for the state-controlled Polish Petroleum and Gas Mining company, said it would explore with the Polish subsidiary of Chevron four license areas in southeastern Poland -- two owned by PGNiG and two owned by Chevron. "By collaborating with Chevron we will be able to draw on its extensive experience in shale gas exploration," PGNiG President Mariusz Zawisza said in a statement Monday. "We hope that this partnership will be beneficial to both parties by allowing us to optimize the costs and improve the effectiveness of our exploration efforts." Neither company offered a reserve potential for the targeted assets. Poland is one of the Eastern European countries thought to be rich in shale natural gas. The U.S. Energy Information Administration estimates Poland may hold more than 700 trillion cubic feet of shale gas reserves.