U.S. oil production has topped 10 million barrels per day, approaching a record set in 1970, but many investors in the companies driving the shale oil revolution are still waiting for their payday. Shale producers have raised and spent billions of dollars to produce more oil and gas, ending decades of declining output and redrawing the global energy trade map. But most U.S. shale producers have failed for years to turn a profit with the increased output, frustrating their financial backers. Wall Street’s patience ran out late last year as investors called for producers to shift more cash to dividends and share buybacks. “‘Give me some cash, please.’ That’s what investors have said,” said Anoop Poddar, a partner at private equity firm Energy Ventures. And yet such calls for payouts remain a debate in the industry as oil prices have recently creeped up to four-year highs. […]