The Problem
A customer was concerned over the performance of their gas compressors and wanted us to investigate. They felt that the performance was declining, because increasing power from the turbine was required to drive the compressor. Normally, a Field Service Engineer would be deployed to do a manual inspection using a borescope. However, the pandemic made mobilising engineers difficult.
Investigation
O4 was deployed offshore and within a couple of weeks, customized performance monitoring displays had been built. Automated reports (like in Figure 1) and notifications were set up. From the raw data, no clear deterioration could be seen in either the turbine or the compressor.
Figure 1
O4 Digital utilized its close partnership with OFS to dig deeper. Highly experienced rotating equipment specialists were assigned to the job and asset health metrics were introduced. First, the gas compressor was analysed for discrepancies in efficiency.
Figure 2
We superimposed the data on the OEM compressor map, and it was found that the compressor was operating within normal limits (see Figure 2). Various other measurements were examined, but no clear root cause could be found. The main issue remained, increasingly more power from the turbine was required to drive the compressor. So, we switched our focus to the turbine performance.
We defined a performance metric for tracking compressor blade degradation. The formulae analysed the compressor’s ability to increase pressure and the effects on temperature. It also incorporated the gas compressibility at either side of the section. It was found that the polytropic efficiency of the compressor section of the turbine was deteriorating over time (see Figure 3). This gave the customer a visual metric to analyse their compressor performance and see what was happening in real-time.
Figure 3
The Solution
O4 Digital utilized its close partnership with OFS to dig deeper. Highly experienced rotating equipment specialists were assigned to the job and asset health metrics were introduced. First, the gas compressor was analysed for discrepancies in efficiency.
Figure 4
This efficiency improvement brought immediate positive results for the entire plant (see Figure 4). A new engine (yellow) became available, and this presented an opportunity to service the two deteriorating compressor blade sets (in blue and orange). An increase in efficiency of approximately 4% was observed. This equates to about 364 extra kW in turbine power per engine, so a total site boost of 730 kW. The power of O4 remote asset monitoring was realised as the problem could be identified remotely. O4 data analytics, combined with the rapid response of our experienced engineers, boosted production by over 40 mmscfd. Not only has the customer drastically reduced their costs, but O4 has helped them to reduce their environmental impact, by burning less fuel to pump more gas.
