Mr. Magness said he and his colleagues, in their hunt for data, have clambered around “in torn jeans” in the dusty repositories of state geological services trying to find old paper records of wells and rock cores. Chevron has drilled two wells on its Poland concessions and is planning to begin another soon.

The company is also planning to reopen one of the earlier wells, in southeast Poland, to perform further tests. Mr. Magness said that what he had found in the early efforts was enough to interest him in investing more time and money. “I am not seeing anything that would tell me to pull the drill bit up and go away,” he said.

Because of fears that the extraction method could pollute drinking water, several European countries, including France, have barred fracking in their territories, despite indications of promising shale gas deposits. Exxon Mobil temporarily halted drilling in Lower Saxony in Germany in deference to local opposition.

Stephan Singer, energy policy director for the World Wild Life Fund in Brussels said that the concerns about hydraulic fracturing included the large volumes of water that it uses for shale gas operations. Another worry: that fracking would damage geological formations, turning them into “a leaky swiss cheese” unsuitable for storing carbon dioxide in the future, as environmental groups hope.

Environmentalists also worry fear that tapping into huge troves of gas will lead to an enormous new volume of carbon dioxide emissions in the atmosphere, Mr. Singer said.

Mr. Magness, a crew-cut New Orleans native, contends that persuasion and data can overcome the environmental resistance. But Chevron has encountered protesters in Poland, including people blocking roads to its drill sites.

“We need to sit down and talk to folks and not have them put themselves in harm’s way,” he said.

He said he was confident that a case could be made to at least some European governments that shale gas could bring them major benefits in terms of jobs and energy security. A big selling point is that successful development of shale gas would lessen the dependence of former Soviet satellites like Poland on gas imports from Russia’s Gazprom monopoly.