Chevron will buy U.S. natural gas producer Atlas Energy for $3.2 billion, excluding debt, giving the oil company a key stake in the fast-growing Marcellus shale field.

The acquisition is the latest by a major energy company to snap up a small player with significant holdings in one of the country's most lucrative energy fields and comes just months after its larger rival Exxon Mobil also bought into the region for nearly $30 billion.

With the deal, which must be approved by Atlas shareholders, Chevron would gain access to as much 9 trillion cubic feet of natural gas in the shale fields in the eastern United States.

"CVX doesn't have much of a U.S. presence in shale, and I think it's an important place to be," Phil Weiss, an analyst with Argus Research, said. "The price looks reasonable."

Chevron, the second-largest U.S. oil and gas company, will pay $43.34 per share, or a 37% premium to Atlas' closing stock price on Monday.

That offer consists of $38.25 per share in cash for each Atlas share, plus a distribution of units in Atlas Pipeline Holdings LPs worth about $5.09 per share.

Chevron will also assume net debt from Atlas of about $1.1 billion, for a total deal value of $4.3 billion.

San Ramon, California-based Chevron recently bought into shale fields in Poland, Romania and Canada, and the move gives it the opportunity to exploit the dense rock formations that have changed the U.S. energy outlook in recent years.

Energy companies have rushed to tap into shale rock formations in states including Texas, Louisiana and Pennsylvania, using a technique called hydrofracturing, or "fracking," in which water, sand and chemicals are injected at high pressure into the rock to form cracks that allow the gas to be pulled out.

But the rush to produce that gas has created a supply glut, and recently pushed natural gas prices to their lowest level in a year, although they have rebounded somewhat to in the past two weeks.

Additionally, environmental groups and homeowners in Pennsylvania have criticized fracking as an ecologically dangerous practices that has often fouled drinking water supplies.

With the deal, Chevron will take over Atlas' 60% stake and serve as the operator of a joint venture in the Marcellus shale with India's Reliance Industries.

Reliance will continue to fund 75% of the operator's drilling costs, up to $1.4 billion.

Atlas' assets in the Appalachian basin include 486,000 netacres of Marcellus Shale; 623,000 net acres of Utica Shale; and a 49% interest in Laurel Mountain Midstream, LLC, a joint venture that intrastate and natural gas gathering lines in the Marcellus.