Private equity fund EnCap Flatrock Midstream plans to invest up to $500 million in startup Tall Oak Midstream LLC, based in Oklahoma City, to fund purchases in emerging resource plays across North America, with an initial focus on the Midcontinent. The EnCap Investments LP affiliate is providing $100 million and has pledged up to $400 million more over time. Tall Oak CEO Ryan Lewellyn formerly was a managing director of DCP Midstream Partners LP's Midcontinent business. CFO Carlos Evanspreviously was a Chesapeake Energy Corp. natural gas sales executive. COO Lindel R. Larison also most recently was a Chesapeake executive, where he served as the manager of construction and engineering.