NEW YORK (Reuters) – After Texas pushed the United States over the last decade to become the world’s biggest oil producer last year, the heart of the shale revolution is starting to show fatigue. FILE PHOTO: A drilling rig is seen at a well site owned by Parsley Energy Inc near Midland, Texas, U.S., May 3, 2017. Picture taken May 3, 2017. REUTERS/Ernest Scheyder/File Photo The volume of crude being pumped out of Texas recently saw its first monthly dip in a year. Oil well productivity in Texas’s Permian basin – the country’s largest oil field – is falling, and the number of drilling rigs operating in the United States declined for six straight weeks before rebounding this week. Those indicators of future U.S. oil production suggest that the massive surge in output over the past two years cannot continue unabated, and instead will shift to a near-term plateau […]