Investigation of Stuck Pipe Incident KH-1 Slaovakia 2013: Root Cause Analysis
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Stuck pipe incidents are a major operational concern during most drilling operations. Even when stuck pipe situations are resolved, they usually require a lot of resources. In the worst case scenario stuck pipe causes loss of the borehole. This Thesis is an investigation of a stuck pipe incident that ultimately led to the loss of an on-shore well drilled in Slovakia. Percussion air hammer technology was used for drilling the hole and foam was occupying the annulus at the time of the incident. The drillstring became stuck during an emergency tripping out of hole following an accident which led to a personal injury at the site. After the hole was abandoned the cause for becoming stuck was still unclear. The thesis aims to decide what caused the pipe to get stuck. First an overview of the situation is established by describing the course of events and essential information about the operation. Acquired information is then analyzed and discussed, noting indications of various stuck pipe causes. The acquired information included hook load logs and cuttings sampled from the well. The cuttings were analyzed with regards to shape, size and type of formation. Cuttings from selected parts of the well were also tested for water reactivity. The indications that were discovered were summarized and compared to possible stuck pipe causes. Fractured formations and reactive formations received the most support from the information that had been provided. Of the two, reactive formations seems more likely due to effectively accounting for type of material found in plug as well as the timing of the incident. Conclusive evidence of a particular cause for the incident could not be determined with confidence.Recommendations for further studies include: Further study of stuck pipe cause if additional information exists at a future time. Creating a diagnostic tool for use in air hammer drilling would help avoiding future stuck pipe incidents. Looking into the correct actions for different stuck pipe causes could also be a part of this study. An evaluation of the protocols for air hammer drilling and tripping could uncover potential risks involved in currently used procedures.