Root Cause Analysis, Condition Monitoring Address MTBR

When an oil and gas exploration and production company with operations in the United States, Egypt and the United Kingdom experienced high pump failure rates on a North Sea platform, a solution was needed quickly. The company, which produces 28,000 barrels a day, had to fix problems caused by sand damage to six pumps used in the reclaimed oil process. Newly drilled sandy wells caused the sand damage that resulted in production stoppages and shortened the mean time between repair (MTBR) rates for the pumps and seals. In the past, solutions implemented by the oil and gas company took two years to execute. So, the company looked to a mechanical seals company and a pump engineering company to find a unified solution that could also increase production reliability.

Drilling into the Problem

Over a span of five years, the pumps on the North Sea oil platform required repair for nine seals. This equated to a 13-month MTBR. However, because of new wells, the sand contamination increased the number of pump failures to six in a one-year time period, or two-month MTBR. During this time, seal repair times usually took four to 10 weeks. Not only did the oil and gas company find keeping the pumps up and running difficult, but also because the pumps were critical to the process, the company grew concerned about high profit losses from mounting lost production.

The Solution

On discovering the root cause of the problem, the oil and gas company relied on condition monitoring services while the defect elimination process took place. A shortened MTBR was addressed through a collaborative effort including the oil and gas company’s mechanical support engineers, the mechanical seals company and a company specializing in pump engineering support services. Condition data was provided by the mechanical seal company to anticipate failures and prioritize spares, including analyzing vibration data to help plan and manage outages. The oil and gas company proactively procured seal spares to help shorten outage downtime. In addition, a defect elimination process was implemented, including redesigning the pumps and seals systems. Upgrades included a range of actions, including increased impeller size to de-bottleneck the process; coating upgrades; and seals were changed from pusher to nonpusher (604DP, or double-ply, assembly to a 670 assembly). In addition, a distributed flush was included to maximize exposure of the seat to the flushed product.

The Results

While the wells at the North Sea oil platform have continued to contain a high sand content, the solutions implemented have allowed the platform to sustain its production output. Current failure rates have dropped to only one failure in six years, or a 72-month MTBR. The oil and gas exploration and production company is now meeting its production targets and has saved approximately $26 million in annual lost production. The oil and gas company decided to defer the overhaul of its pump from 24 months to approximately 72 months because of the ongoing condition monitoring capabilities that are now in place. This represents an annual savings of an estimated $105,000.