Electrical Condition Monitoring Transforms Maintenance

The stakes are high for the EOR operations at Chaparral Energy’s Borger, Texas, and Liberal, Kan., facilities. Using captured CO₂, Chaparral has been able to increase its production nearly 18-fold, from an average of 272 boe/d to 4,800 boe/d for its oil fields in the Oklahoma and Texas Panhandle region. The CO₂ is captured from a fertilizer plant in Borger and from an ethanol plant in Liberal and then compressed and transported by pipeline to be used in Chaparral’s tertiary recovery of oil. Without Chaparral’s EOR operations, this 100% man-made CO₂ would be released into the atmosphere.

Chaparral’s EOR operations at the Borger and Liberal plants use a number of highly critical medium- and low-voltage motors as well as pumps, fans and compressors. If this equipment goes down unexpectedly, the headaches are real for plant operators.

“If one of our compressors were to fail unexpectedly, our production output materially drops and we work in reactive mode. We needed a predictive maintenance system so we could be proactive and to give us the time to plan our repairs,” said Gerald Herl, Liberal and Borger plant supervisor.

FIGURE 1. The Ariel JGJ6 reciprocating compressor developed loose bolts. (Source: Veros Systems Inc.)

Monitoring options

Traditional options for monitoring motors and their driven loads have been less than ideal. Operators frequently rely on either handheld or online vibration monitoring. While handheld monitoring is attractive from a price standpoint, it is not continuous and is therefore prone to missing events. Online vibration monitoring is expensive and complex to install since it requires drilling into critical equipment. Chaparral explored new options to improve performance.

FIGURE 2. The Veros ForeSight software offers fault indicator trends. (Source: Veros Systems Inc.)

Electrical waveform condition monitoring

Looking for an alternative to traditional monitoring, Chaparral CO₂ Midstream evaluated electrical waveform condition monitoring. These systems continuously monitor the current and voltage signals supplied to a motor and use machine learning algorithms to compare real-time signals to what has been observed to be “normal” for that motor and its driven load. The monitors are simple to install since they use clamp-on transformers, which install easily at the motor control center or variable frequency drive enclosure.

Chaparral installed the Veros ForeSight system on 18 motors and driven loads. Since installing the system, Chaparral has been able to continuously monitor more than 300 metrics related to equipment health and performance. In recent months the system provided Chaparral advance notice of two developing equipment issues, allowing operations to proactively repair or replace equipment without lengthy shutdowns.

Case histories

Last year Veros notified Chaparral of an issue on a Siemens 4812S motor and Ariel second-stage reciprocating compressor (Figure 1). When the maintenance team observed the equipment, everything looked and sounded fine. In fact, the plant had recently conducted vibration testing on the equipment, so it seemed unlikely that something could actually be wrong. To be safe, the plant requested additional vibration testing on the equipment.

Once the vibration analysis was complete, it showed possible looseness on the crankshaft of the compressor. Chaparral shut down the compressor and determined that the coupling bolts were indeed loose. After tightening the bolts on the flexible disc coupling, the compressor was returned to operations and ran smoothly.

Preventive maintenance saved Chaparral both in equipment cost and lost production. The next scheduled vibration monitoring was a month away, plenty of time for things to go wrong. Had the bolts not been tightened, the coupling likely would have failed catastrophically, costing Chaparral $20,000 to $30,000 in equipment cost and two to three weeks in downtime.