Last month, Exxon Mobil made a major investment in XTO, one of the largest shale gas producers in the U.S., and the in the weeks since then, a number of other major oil companies have moved aggressively to establish or expand their presence in the shale sector.

Earlier this week, five companies submitted bids totaling $129 million — twice as much as the amount forecasted — for the rights to drill in the Marcellus Shale natural gas formation in northern Pennsylvania. This growing interest comes amid mounting evidence of the vast volumes of shale gas, which by some estimates, on a global basis, exceed the world’s oil reserves.

Other shale areas, such as the Haynesville Shale in Texas and Louisiana, are also seeing strong interest from energy producers.

The last time we wrote about shale, we noted that improved production technologies would be key to generating a steady supply of shale gas, and helping to ensure mass production. Of course, this path to mass production is never a smooth one, even for the most promising and abundant energy resources. In addition to the technology challenges associated with production challenges, regulatory challenges are also likely. Already, shale producers in New York say that onerous regulations are driving them out of the state.

We’re not sure what the coming year has in store for the shale gas industry, but we do know that it’s an area we all must watch closely. We’re encouraged by the growing interest in these sites and we need to make sure that the projects, which could contribute significantly to our domestic natural gas supply, are allowed to proceed.