Abstract
The use and application of compressors cannot be overemphasized in the oil & gas industry and the continuous availability of this rotating equipment is critical for maintaining safety and production profits for both offshore and onshore applications. In parallel, a compressor will degrade in its performance due to fouling and wearing and is not able to deliver the designed performance throughout its life.
As compressors continue to perform, the speed curves shift to lower heads and throughput and performance deteriorate. Based on the fact that the magnitude of the shift is different for each speed, an innovative technique for compressor performance modeling and diagnostics has been developed. It enables the actual performance of a compressor being modeled over a wide range of speeds and related flows so that the compressor performance and its operational limits can be successfully estimated. In this approach, OEM performance data is firstly used to establish an initial compressor performance model. Then field test data for a compressor is obtained and used to adapt compressor performance model to ensure the model represent the actual performance of the compressor over a wide range of speeds. As compressors continue to work, the characteristic map of the compressors shift to new positions due to recoverable and non-recoverable degradation occur to the compressors, causing the deviation of compressor operational parameters and settings. This shift represents the degradation of the compressor and can be identified by using field test data and the compressor diagnostic model described in this paper. Several methods for compressor monitoring and fault diagnostics exist. The diagnostics based on performance analysis is one of the most effective tools where the analysis of gas path (GPA) parameters provides information on the severity of degradation. The concept of GPA Index is introduced to assess the success of the diagnostic results. The performance and diagnostic results provided by the compressor diagnostic approach offer useful information to compressor operators to uphold compressor performance and to improve maintenance schedules and avoid unexpected failures. These factors will ultimately lead to an increase in revenues and safe production.
