Root Cause Failure Analysis as a Tool for Investigating Operational Failures: A Case Study

Abstract

Abstract Production liner cementation in deepwater wells is critical to contain formation pressures and provide zonal isolation. This is especially challenging in the Gulf of Mexico because of depleted zones, small drilling margins, and HPHT reservoirs. Failure to achieve zonal isolation with the primary cement job leads to added cost and time for remedial operations. A recent primary cement job failure in the Viosca Knoll Block, located in the Gulf of Mexico, prompted the use of an established tool, Root Cause Failure Analysis (RCFA), in a novel way to identify the causes of the incident and avoid repeating the same mistakes in future wells. A team of operations and engineering personnel was assembled to investigate the cause of the primary cement job failure that resulted in nonproductive time and cost of approximately 7 days and $3 MM, respectively. RCFAs have typically been performed on equipment failures; however, this RCFA was conducted by the operator on a non-equipment related failure. The RCFA team initially collected data available from both the planning and operation phases of the job in order to identify which elements of the cementing process contributed to the cement job failure. After identifying the root cause, the team communicated learnings to office and rig-based personnel, developed a new tool for real time monitoring of primary cementation, and adjusted plans for upcoming primary cement jobs. The findings from the RCFA were applied to a well on another asset owned by the operator, with which the production liner was successfully rotated throughout cementation for the first time. The RCFA identified that the cement job design was not a contributing factor; instead, the root causes were operational and started during circulation of drilling fluid prior to cementing operations. The learnings from the RCFA were transferred to both office and rig-based personnel, influencing engineering and operations plans for subsequent wells. Furthermore, the investigation identified previously unknown issues and showed that the use of the RCFA process was an effective approach that can be standardized and scaled to determine root causes of future operational failures.