Injecting new life into an oil rig pump

20 January 2020

A water injection pump has been brought back to life to maintain productivity after lying dormant for seven years.

Leaving large pieces of rotating equipment dormant for long periods of time is routine in industry sectors with a high level of mechanical redundancy. However, if equipment is not preserved correctly, then getting them back into service quickly can be a challenge. 

For one offshore platform in the Gulf of Mexico, calling the original equipment manufacturer (OEM) was the deciding factor in getting a water injection pump back up and running in time to start operating when it was needed.

Offshore drilling rigs aim to maintain peak performance throughout their production life cycle. One of the crucial pieces of equipment in this process is the water injection pump, which is used to pressurise the well and maximise production rates. So, it is important to carry out periodic maintenance of these key assets to ensure they continue to perform reliably. However, all is not lost if the maintenance schedule is overlooked, as shown in a recent project that involved Sulzer revitalising an injection pump that had remained dormant for many years.

Borrowed parts
The history of what exactly happened prior to the need for recommissioning this standby water injection pump had been lost during various changes in personnel working on the platform. From what information could be gathered, it appeared that of the two water injection pumps on the rig, #2, developed a leak in a Graylock fitting in a piping spool, downstream of the pump itself.

To resolve this issue, pump #1 was shut down and the necessary parts removed to keep #2 operational. Since that time, pump #1 had remained out of service, without any preservation actions –  while pump #2 operated continuously. However, after seven years use, it had begun to drop in efficiency, to the point that the platform operator needed to overhaul the pump to ensure continued productivity.

To achieve the overhaul of pump #2 it was necessary to assess the condition of pump #1, resolve any issues and return it to normal operation. This would enable pump #2 to be shut down and overhauled, without an interruption to the productivity of the platform.

Working in the tight confines of an oil platform takes experience and close cooperation with the other personnel. Mark Lindsley, field service engineer for Sulzer, explains: “We work closely with the platform staff to ensure that every project is completed safely and to the highest standards.”

Considering the harsh marine atmosphere that surrounds the injection pump equipment, most of the components still looked to be in good condition. The inspection process highlighted all the areas needing attention, much of which could be completed during the initial visit.

Following the inspection, Lindsley rebuilt the pump thrust bearing and the non-drive end (NDE) radial bearing was replaced using stock that was held on the platform. The gearbox had been cleaned out previously and the lube system flushed in preparation for reassembly when the alignment of the drive train was checked and adjusted.

The most obvious issue was the missing piping spool, which would have to be manufactured before the drive train could be recommissioned. In addition, the inspection found that the motor to gearbox coupling would need to be rebuilt, the almost 6.000 kW electric motor would need to be tested and an additional shim would be needed for the gearbox to pump coupling.

Back to life
Following the initial visit, Sulzer engineers set out to assemble a new pipe spool and the parts required to rebuild the coupling. When all the necessary parts were available, Sulzer returned to the platform to complete the installation work.

The charge pump was cleaned, aligned and coupled, allowing the water injection pump to be started. Once online, the pump performed with very low vibration levels and the operator agreed that it should continue to operate while being monitored.

The successful start-up of pump #1 has enabled the platform to start planning the refurbishment of pump #2. Continued operation will prove the reliability of the repaired pump and ensure optimum production levels of the well are maintained.

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