Tulsa-based Argonaut Private Equity said March 22 it acquired assets of Pioneer Well Services, subsidiary of Pioneer Natural Resources. Argonaut rebranded the operation in Permian Basin as American Well Services; it provides well service rigs for workover or completions and wellsite support, including fluid transfer, hot oiling, frac tank rental and wellsite construction. Assets include fleet of rigs, water hauling trucks, frac tanks, hot oil units, fishing packages and heavy machinery. American Well Services will partner with Argonaut’s existing portfolio company Nichols Oil Tools.