Energy companies and oil trading firms that teamed up to build several mini-refineries that convert a swelling surplus of ultra-light U.S. crude into fuels for export seemed like a pretty safe investment bet for a while. The bet was built on several converging dynamics: an ever-rising supply of condensate; a U.S. refining system built to run heavier crudes; and a longstanding ban on crude exports that appeared unlikely to unwind amid partisan paralysis in Washington D.C. Now, as U.S. oil output reverses its five-year rise and after lawmakers ended the 40-year-old export ban this month, oil executives and analysts question the wisdom of nearly $1 billion worth of so-called condensate splitters built over the past year, and the future of another $1.2 billion planned. Traders are wondering what will happen with existing splitters […]