Technical Guidance Document Number 3: Centrifugal Compressors with “Wet” (Oil) Seals

This document provides technical guidance to Partners of the CCAC Oil and Gas Methane Partnership (OGMP). It is one in a series describing a core source of methane emissions from oil and natural gas production operations. The guidance documents introduce suggested methodologies for quantifying methane emissions from specific sources and describe established mitigation options that Partners should reference when determining if the source is “mitigated.”

Centrifugal compressors have seals on the rotating shafts that prevent the high-pressure natural gas from escaping the compressor casing. These seals can be high-pressure oil ("wet”) seals or mechanical gas (“dry”) seals, which act as barriers against escaping gas. The wet seal centrifugal compressors circulate oil under high pressure between rings around the compressor shaft, forming a barrier against the compressed gas to prevent its escape to the atmosphere.