Enterprise Products Partners L.P., an energy pipeline investor headed by a Houston lawyer-turned-billionaire, announced Wednesday that it had acquired a controlling two-thirds stake in marine terminal operator Oiltanking Partners L.P. in a $4.6 billion deal.

Four Am Law 100 firms have hitched themselves to the transaction, with Andrews Kurth and Akin Gump Strauss Hauer & Feld advising Enterprise, while Skadden, Arps, Slate, Meagher & Flom and Vinson & Elkins representing Houston-based Oiltanking.