Maximizing Reliability—Well Integrity Statistics and Risk Reduction Strategies

This paper presents typical multi-fractured horizontal well failures together with potential mitigation strategies. The discussion is based on information compiled over the last decade from operations in the United States, Argentina and Canada. The analysis focuses mainly on well integrity and well accessibility events associated with production casing, production liner and tubing strings.

A comprehensive failure database covering over 150 cases from operations in shale plays was created. Failure here is defined as any event that led to either compromised well integrity or loss of well accessibility. The database was populated with verified cases from various operators and product origins, as well as various sizes and types. Causes were grouped in ten different categories, resulting in conclusions for the following well stages: strings’ installation, stimulation, and production.

The analysis allows us to estimate the failure occurrence per stage and to infer the inherent failure risk for the different phases of a well's life cycle. Moreover, the obtained overall failures ranking shows which categories require more stringent attention in order to avoid problems throughout the life of a well.

The database analysis also revealed distinctive failure patterns for the different stages. These deliver important lessons on how to select tubular goods, design the installation, or even operate the well in order to diminish the failure risk.

This work represents an important effort to quantify the metrics and impact of the different well failures during the installation, stimulation and production stages throughout the past decade. The conclusions were obtained by using information from different operators, regions and product types, which means lessons learned can be considered as a valuable reference regardless of the particular contexts.