The most important word in that sentence: "grow," as in "accelerate." That's an important distinction, by the way. "Grow" could simply mean continued "growth" on the same trajectory. The story actually uses the word "accelerate." To accelerate means to grow MORE than current rate of growth.
Second most important word in that sentence: "decades." The acceleration will continue over the next three decades. Here's the lede:
U.S. natural-gas production will accelerate over the next three decades, new research indicates, providing the strongest evidence yet that the energy boom remaking America will last for a generation.
The most exhaustive study to date of a key natural-gas field in Texas, combined with related research under way elsewhere, shows that U.S. shale-rock formations will provide a growing source of moderately priced natural gas through 2040, and decline only slowly after that. A report on the Texas field, to be released Thursday, was reviewed by The Wall Street Journal.As the Journal notes, that growth will be generational.