In a global first, Mubadala Petroleum in Thailand has successfully completed a three-month trial of a new technology designed to improve the operational performance of the regular program of well maintenance workovers required for its Gulf of Thailand fields. The trial tested the use of an innovative modular Rigless Pulling Unit (RPU) in place of a conventional Hydraulic Workover Unit (HWU) in a program of workover operations. Historically, the RPU used by most operators worldwide for Plug and Abandon (P&A) type of operation. However, Mubadala Petroleum has pushed the technical limits for the RPU to perform ESP change out and running upper/lower completions (Re-completion) on existing wells that has ESP failures, or any recompletion opportunities. During the trial period, this new unit achieved similar operational efficiency to a HWU, while proving its capabilities to execute the most complicated tasks that are challenging even for the HWU, in terms of reducing rig time, well cost, and most importantly minimizing the HSE risks. This technology can be developed to be a "fit for purpose" intervention method for the future workover, recompletion and decommissioning activities. The utilization of RPU for a long well services campaign, for post-drilling completions, for slot recoveries and for a decommissioning campaign will have more potential of cost saving vs using the Rig or HWU. With this first worldwide successful trial of a RPU for well workover operations, we have opened the doors for new opportunities to perform workover activities other than with standard hydraulic workover rigs. The RPU technology offers many advantages and capabilities to perform more efficient complex workovers or recompletion operations. Material presented is from actual workover operations, including electrical submersible pumps (ESP) change outs and cycling lower completions, wellbore cleanout, etc. It will also display the operational efficiencies increase and risk reduction achieved.