Failure Analysis

Root Cause Failure Analysis is Essential for Failure Frequency Reduction in Wells With Artificial Lift

Most failures associated with artificial lift systems can be attributed to one of three downhole components-pump, sucker rod, or tubing. A pump, sucker rod, or tubing failure is defined as any catastrophic event requiring servicing personnel to pull or change-out one or more of these components. By this definition, the failure frequency rate is the total number of component failures occurring per well, per year. Marginally producing wells with high failure frequency rates are often classified as "problem" wells and effective failure management practices can mean the difference between operating and plugging these wells. Failure management includes preventing, identifying, implementing and recording the "real" root cause of each failure and is central to overall cost-effective asset management. For the purpose of this photo essay, we will deal only with sucker rod failures.

Cost-effective failure management begins with prevention, and the time to stop the next failure is now-prior to an incident! Simply fishing and hanging the well on after a sucker rod failure will not prevent failure recurrence. In fact, most failures continue with increasing frequency until the entire rod string must be pulled and replaced. Achievable failure frequency reductions require accurate failure root cause analysis and the implementation of corrective action measures to prevent failure recurrence. A database capable of querying the well "servicing" history is needed to track and identify failure trends. Once a failure trend is identified, remedial measures should be implemented during well servicing operations to prevent premature rod string failures. The database failure history should include information on the failure type, location, depth, root cause, and the corrective action measures implemented.

Sucker rods can be caused to fail prematurely. Understanding the effects of seemingly minor damage to rod strings, and knowing how that damage can produce catastrophic failures, is very important for production personnel. Sucker rod failure analysis is challenging and you need to be able to look past the obvious and seek clues from the not so obvious. All production personnel should have adequate knowledge and training in failure root cause analysis. Understanding how to identify failures and their contributing factors allows us an understanding of what is required to correct the root cause of the failure. Every step that can be taken to eliminate premature sucker rod failures must be taken. On-going training programs concerning sucker rods should include formal and informal forums that advocate following the recommendations of manufacturers for artificial lift design, care & handling, storage & transportation, running & rerunning, and makeup & breakout procedures. A variety of training schools are currently available and, with advanced notice, most can be tailored to meet the specific needs of production personnel.