Oilfield production has traditionally captured high value crude oil while venting or flaring lesser-value natural gas. Demand for natural gas combined with increasing environmental regulations have driven many upstream companies to implement Vapor Recovery Units (VRU's). In this paper we will examine how vapor recovery units work and look at the benefits of optical oxygen measurement in the vapors that are captured by these systems.
Oxygen Measurement Challanges
Oxygen measurement at the vapor recovery unit has been problematic for many sensing technologies. Both paramagnetic and tunable diode laser (TDLAS) oxygen analyzers are relatively new technologies. These products work well in % oxygen measurements but lose their accuracy at the low part-per million levels required for these applications. Electrochemical oxygen sensors (sometimes referred to as a "Clark Cell") have typically been used for these applications because of their ability to measure at low O
2 levels. Unfortunately these sensors have their own application issues.