Implementation of Torque and Drag Analysis to Simulate Forces While Running in Hole Electric Submersible Pump - ESP Assemblies, to Reduce Power Cable Mechanical Damages

Abstract

Electrical failures of the Electric Submersible Pumping ESP systems reached a record high in various Northern fields in 2014. A study was undertaken to identify and understand these failures and their root causes. The analysis revealed that the main cause of the system failure was either the power cable or the motor lead extension (MLE). Through continued developments in technology, the components of the ESPs have been upgraded to increase their performance, efficiency, and run life. In Llanos Norte operation, located in east Colombia, an increase in power cable failures was observed between 2012 and 2014. Those failures represented 50% of the total failures associated with downhole equipment with an average run life of 300 days and the main cause was mechanical damage to the cable sustained during installation. After a detailed well-to-well analysis to identify fault patterns, different reasons arose such as well tortuosity, high run-in-hole speed, changes in cable specifications and deformations caused by the accessories used to protect the cable. All of these items resulted in mechanical damage to the outer armor of the cable, exposing the insulation system to well fluid, which caused an increase in infant (less than 30 days of operation) and premature (less than 365 days of operation) failures. As an immediate action plan, a decision tree was created to determine run-in-hole speed according to different factors such as: well deviation, outside diameter of equipment and the internal diameter of casing; supporting the analysis with calculations of torque and drag. There were also additional actions implemented to reduce cable failures such as: changes in cable specifications (thicker armor and geometry), training the personnel involved in ESP installation (rig and ESP vendor), changes in the tools used for cable handling, use of new accessories for cable protection and upgrading power cables with lead jackets for applications in gassy wells. This paper presents a summary of the different solutions implemented after a thorough analysis carried out with an interdisciplinary team composed by personnel of the Field Operator and ESP vendors. The implementations of all actions represented almost MMUSD$ 4 in savings in three years over a population of 395 wells.