Pennsylvania may sit on bigger shale gas bonanza

* Utica Shale may not be Marcellus but still significant

* Proximity to Marcellus could make it cost-effective

By Jon Hurdle

PHILADELPHIA, July 1 (Reuters) - Is there even more natural gas than thought encased in the rock below Pennsylvania?

The state that is already estimated to have enough gas in its Marcellus Shale formation to meet total U.S. needs for a decade or more may have additional reserves trapped in geological strata above and below the Marcellus, some energy companies believe.

Test wells sunk in recent months have yielded promising quantities of gas that may indicate major new reserves of a fuel that would reduce carbon emissions, cut U.S. petroleum imports, and generate thousands of jobs.

If confirmed, the new fields would also be economically attractive because they could be exploited by gas rigs that are already drilling into the mile-deep Marcellus, a rock belt that runs from Virginia to New York and extends under Lake Erie to Canada.

One of the fields, the Utica Shale, has already generated interest in the Canadian province of Quebec where a number of horizontal test wells have been drilled, and that optimism is spreading to Pennsylvania, birthplace of the world's oil industry in the mid-19th century.

Range Resources Corp. (RRC.N: Quote), a Texas-based gas driller that is active in the southwestern Pennsylvania portion of the Marcellus, said it has successfully tested two wells, in the Upper Devonian Shale above the Marcellus, and the Utica, below it. It plans to release more details in the coming months.