Electrical Savings – Even the small units!

Often the smaller assets in your fleet that aren’t moving huge amounts of gas don’t always get the attention they deserve. This can cause opportunities to be overlooked, or not even realized.

Today we are looking at an asset that was compressing a small amount of gas but was bypassing significantly due to its configuration. The real kicker here is that it is driven by an electric drive that does not have a VFD (Variable Frequency Drive) which allows the engine to operate at various RPM. In this case we are fixed at the running RPM of 1192, so crippling the unit down to match what the field is delivering can sometimes be challenging.

In this example, the asset was setup with all throws Double Acting and the pockets fully closed. Good for when you are wanting to pull as low as possible and get the maximum throughput at a given suction pressure, not so great when the field is only delivering ~14 e3m3/d (~0.5 mmscfd) but the asset is compressing closer to 23 e3m3/d (0.8 mmscfd). Reported flow is shown in red, and our final stage cylinder flow shown in blue below:

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With this in mind, we came up with a configuration that closed that gap and reduced the amount of bypassing, in turn also reducing the amount of electricity required to move the production. By switching the unit over to SACE (Single Acting Crank End) for Stages 1 and 2 and leaving Stage 3 as double acting with pockets closed, we simulated that we should be able to cripple this unit to better match the field conditions.

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After the changes were implemented and new Enalysis reports ran to evaluate, it was clear from the chart above that we were able to maintain our production from the field and reduce the amount of bypassing occurring and reduce electrical consumption by ~1225 kWh/d!

This is a great reminder that every asset should be optimized for the conditions that the field is delivering, as savings and opportunities can exist even on the smaller assets. If you feel there are opportunities in your fleet of compression that are not being realized or acted upon, the engineers at Detechtion would love to hear from you and ensure your fleet is optimized.