Merger and acquisition activity in the U.S. oil and gas sector has surged to almost $200 billion in the past year. This occurred as the biggest producers swallowed up smaller rivals in a race for scale that has redrawn the energy landscape in the U.S. The industry has gone from about 65 to 41 publicly traded oil and gas companies in the U.S. in less than five years. Not surprisingly, the country’s richest shale area – the Permian Basin – has been the focus of much of the activity over the past five years. Just since last July, companies including ExxonMobil (XOM), Chevron (CVX), and Occidental…