A floor crew pull steel pipe out of a natural gas well in the Barnett Shale of Fort Worth, Texas that is owned by Chesapeake Energy Corporation. Robert Nickelsberg | Getty Images

The shale drillers behind booming U.S. oil and natural gas output have survived a bevy of challenges in recent years, from a historic oil price downturn to an effort by OPEC to wash them out of the market with a flood of cheap crude. Now, with U.S. output at all-time highs near 12 million barrels per day, the industry is facing a new obstacle: how to keep growing output amid a wave of belt-tightening that is cutting billions of dollars from capital budgets. Publicly traded shale drillers emerged from the 2014-2016 downturn with a new mandate from investors to get their finances in order and start generating value for shareholders. For years, drillers have spent more cash than they generated, borrowing heavily to snap up acreage and increase their output at seemingly any cost. The latest round of quarterly earnings reports shows many shale drillers are cutting spending to meet investors' demands. That is translating into lower expectations for oil and gas output from the companies, which rely on advanced drilling methods like hydraulic fracturing to free oil and gas from shale rock formations. But even with these frackers now pursuing the elusive goal of drilling at a profit, forecasters expect another blockbuster year for U.S. output. After surging by 1.6 million barrels per day last year, making the U.S. the world's biggest producer, average annual American output is poised to grow by more than 1.4 million bpd in 2019, according to the Department of Energy.

However, there's doubt about those forecasts in some corners of the market. "We've seen a lot of people guide that 2019 [production] will be flat on the fourth quarter of this year, so while you'll see year-on-year growth in U.S. production, it's going to decelerate from '18 levels," said Ben Dell, managing partner at private equity fund Kimmeridge. "Fundamentally I think supply estimates for the U.S will disappoint," he told CNBC's "Squawk Box" on Monday. Heading into the earnings season, analysts at PiperJaffray's Simmons Energy expected oil and gas output from the exploration and production companies they cover to grow by 13 percent. Four weeks into the reporting period, they knocked their growth forecast down to 10 percent. But as you drill down into the data, it becomes clear why total U.S. output continues to climb. Drilling intelligence firm RS Energy currently expects the universe of companies it analyzes to cut spending by about 7 percent from last year.