Like many shale companies, Pioneer was pumping a lot but making little. It was spending hundreds of millions more than budgeted as it strained to meet a goal Mr. Sheffield set years back—producing a million barrels of oil and gas a day within a decade, enough to rival OPEC nations such as Libya. So in February, the company’s board replaced Chief Executive Timothy Dove, who had presided over the cost overruns, with Mr. Sheffield, who had retired as CEO in 2016, and asked him to engineer a turnaround. Mr. Sheffield has since embarked on an extreme belt-tightening regimen at the Irving, Texas-based producer. Pioneer is cutting more than one-quarter of its workforce, including a cadre of senior executives, in part through layoffs and buyouts. Among those who are leaving is Mr. Sheffield’s own brother, Thomas Sheffield, the company’s vice president of health, safety and environment. The million-barrel-a-day goal? It’s […]