ADC was tasked to witness a System Integration Test of a Drilling package.
The ADC specialist considered the results of a system integration test conducted by the original equipment manufacturer (OEM) to be lacking due to the omission of certain operational scenarios.
An ADC test plan was produced to provide assurance that the drilling package operated correctly under normal conditions. The content of the test was agreed between ADC and the Drilling Contractor Operations Department and sequence of events was agreed with OEM. It was considered by ADC that there was an Operational requirement to conduct offline stand building during drilling operations. Therefore, the auto driller system was used to move the top drive up and down during stand building operations.
During the test, this simultaneous operation caused a Zone Management System (ZMS) problem. When drillfloor equipment was moved, the drawworks stopped lowering. ADC recognised that the fault lay in the ZMS functionality and suggested that the computers drill floor height value may be in error. OEM engineers reviewed these settings and found that whilst the ZMS drill floor setting should have risen to 6m during Auto Driller operation, that the software setting was actually 28m and that this error had prevented simultaneous Stand Building and Drilling operations.
Once the issue had been resolved, the OEM demonstrated the correct functionality of the ZMS. This fault was found to be a base line software issue causing a fleet wide problem affecting another 4 rigs and the OEM personnel thanked ADC for their assistance in this matter.
Had ADC not insisted on the conduct of this test, the operational efficiency of a fleet of 5 rigs would have been impaired; simultaneous drilling and stand building operations would not have been possible and a dormant fault in a safety critical system would have remained unidentified.
Operational scenarios must be used during acceptance testing as manufacturer commissioning tests do not always fully consider the interaction between various machines under all envisaged operational circumstances. Consequently, there can be dormant failures that only become evident under a specific set of circumstances.
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