Oil firms hope to repeat a trick that yielded big gas supplies in America

ACROSS Europe, a stealthy land-grab is under way. Exxon Mobil is drilling in Germany’s Lower Saxony. ConocoPhillips has joined 3 Legs Resources, a small firm based on the Isle of Man, to explore a large tract of land in Poland. Austria’s OMV is testing geological formations near Vienna. Shell is targeting Sweden. A host of smaller firms is fanning out across other countries, including France. They are all looking for natural gas trapped in shale (a type of flaky sedimentary rock)—a resource that has transformed the market for gas in America and may have a big impact on Europe, too.

America’s natural-gas stocks are at record highs and prices have collapsed. The country, one authority proclaimed in July, suddenly has 100 years of supply. There is even talk of converting planned import terminals for gas into export terminals. …