Investigation of the correlation between increased error in hydrocarbon dew point determination and high CO2 content in natural gas

Abstract

Hydrocarbon dew point (HCDP) is a critical gas-quality parameter in natural gas transmission and underground storage, because liquid hydrocarbon dropout may affect pipeline integrity, gas metering, and process equipment. This technical note reports preliminary evidence that elevated CO₂ content is associated with abnormal HCDP response in operational monitoring data. The underlying dataset comprised 2,377 accepted time-stamped observations grouped into five anonymized campaigns (BV5-1, BV5-2, BV7-1, MR-1, and MR-‍2). For inferential analysis, campaign-level means were used to avoid pseudo-replication. The full model yielded HCDP = -‍14.13 + 5.51 · CO₂, with R² = 0.471 and p = 0.201. An exploratory sensitivity analysis excluding the influential BV5-1 campaign yielded HCDP = -‍22.95 + 8.72 · CO₂, with R² = 0.991 and p = 0.004, but this filtered result is not used as the primary inferential claim. The discussion clarifies analyser measurement principles, proposes a plausible CO₂ interference mechanism, compares the observed bias with typical direct-analyser accuracy, and outlines a laboratory validation roadmap using synthetic gas mixtures. The results support the interpretation that the observed effect is operationally important, while also showing that broader controlled validation is still required.