ADC was tasked to provide operational support of jacking systems during rig moving operations.
Throughout the course of the drilling campaign, the rig crew had been changed out and were unfamiliar with the jacking system prior to the arrival of ADC. They were not trained in the specific jacking system equipment, functionality, modes of operation or procedures and processes. The jacking system had been started up but due to the large number of faults and alarm, the crew elected to switch it off and leave it off.
When ADC arrived, the jacking console was switched on there were multiple alarms that would not clear. The rig crew were unfamiliar with the meaning of the alarms or of their implications. ADC worked through the alarm list with the crew systematically addressing and correcting the faults and clearing the associated alarms to achieve a fully operational jacking system.
As a result of the crew’s unfamiliarity with the jacking system, there had been a reluctance to conduct checks or maintenance work on the system. The maintenance procedures for the yearly Jacking System inspection were reviewed by ADC and were considered to be unfit for purpose because many of the systems and components, essential to correct function of the jacking system, were not covered by the maintenance procedures provided. Consequently, it was considered that very few of the faults that were identified during ADCs inspection could have been detected by the crew or have been prevented by using the maintenance work orders in place at the time.
System Damage Significant damage had been caused to the Rack Phase Differential (RPD) measurement system which is used to measure the difference between individual chord heights. Wiring had been ripped out of the rear of one encoder communication modules. It was found that the RPD measuring wheel mechanism had been sticking due to lack of lubrication. It was further established that the connecting cables were too short to permit RPD wheel retraction from the Rack to permit rotation and lubrication application to free it off. It was considered that the cable and module damage may have occurred whilst the crew were trying to free off the wheels and lubricate them. ADC identified the fault, confirmed the availability of a spare communication module and confirmed correct system communication following the repair.
The lack of crew familiarity with the equipment and out of date maintenance procedures had resulted in damage to RPD monitoring equipment. The control system prevented operation of the Jacking System due to the lack of monitoring and the possibility of leg structural damage.
The crew were unfamiliar with the implications of the alarms and had the crew used the RPD override facility, it could have resulted in severer damage to the Jack up legs due to the lack of RPD information.
Due to the large number of faults, equipment damage and lack of operator familiarity, it was considered that without ADC participation that the jacking operation could not have occurred.
Modern control systems are designed to protect the equipment, vessel and prevent operator error. In order to achieve this it is essential that crews are adequately trained on the systems that they are operating. This includes understanding the equipment, the principles of operation and the meanings and implications of alarms. Adequate documentation of the systems must be available to the crew to explain the meaning of alarms and fault indications. Maintenance procedures must adequately reflect the equipment and systems onboard.
ADC recognise that modern control systems are designed to protect the equipment, vessel and prevent operator error. In order to achieve this it is essential that crews are adequately trained on the systems that they are operating.
ADC considers, through discussion and feedback with API, that implementation of API 16A and 20E standards is critical in mitigating further equipment failures with subsea BOP systems.