EX-21.1 2 d447869dex211.htm SUBSIDIARIES OF THE REGISTRANT

Exhibit 21.1

Subsidiaries of the Registrant

Name |  | State of Incorporation or organization
Ambar Lone Star Fluid Services LLC |  | Texas
Patterson Petroleum LLC |  | Texas
Patterson-UTI Drilling Canada Limited |  | Nova Scotia
Patterson-UTI Drilling Company LLC |  | Texas
Patterson-UTI Drilling International, Inc. |  | Delaware
Patterson-UTI Management Services, LLC |  | Delaware
Universal Pressure Pumping, Inc. |  | Delaware
Universal Well Services, Inc. |  | Delaware