Oneok is buying $280 million of pipelines to accelerate its ability to capture commercial synergies and earnings growth.Oneok (OKE 0.66%) surprised many in the midstream sector last year when it agreed to buy Magellan Midstream Partners in a massive $18.8 billion deal. The transaction enhanced its diversification and growth profile. It expects the deal to deliver free-cash-flow per-share accretion of more than 20% annually through 2027, fueled partly by capturing at least $200 million of synergies each year ...