By Sergey Kotov and Hans-Christian Freitag HOUSTON-Unconventional resources have made the United States the world's largest oil and natural gas producer, hands down. But if developing North American tight oil and shale gas plays is to remain sustainable at lower commodity prices, the industry must think and act differently to improve production, optimize long-term reserves recovery, and enhance overall development economics. The first wave of the unconventional oil and gas revolution was driven by extensive horizontal drilling and hydraulic fracturing. It was aided by high demand, strong commodity prices, and ready infrastructure from America's conventional oil and gas plays. The goal for the next wave of unconventional development is to enhance production and improve recovery rates at lower operating costs. JULY 2015 71