Proposal and Experimental Trials on an Autonomous Robot for Rigless Well Intervention

Well interventions, especially in offshore wells, are costly and usually very time-consuming to conduct. This is related mainly to the need for a rig or a similar unit to perform these operations. In this paper we propose the development of an autonomous robot for rigless well interventions. The robot will be inserted through the tree using a special tool. This proposal will result in significant cost reduction by eliminating the rig when performing light-workover operations in offshore locations. This reduces intervention time because a simpler unit might be used to deploy the robot. Examples of operations that could be performed by the robot are production logging, gas-lift valve replacement, sliding-sleeve opening and closing, and plug insertion or removal. To evaluate this proposal, a conceptual robot was designed. The feasibility of this conceptual robot was evaluated theoretically. After that, a simplified test robot was constructed to test critical aspects experimentally, in laboratories, and in a test well. The traction system, energy storage, and a positioning algorithm were evaluated. In this paper we will outline the intervention strategy proposed, perform a theoretical evaluation of this proposal on the basis of the conceptual robot, and present experimental results obtained with the simplified test robot.