A fast technique to measure the dewpoint pressure of a retrograde condensate gas using a microfluidic volume

A new method to determine the dewpoint pressure of a retrograde condensate from a fast, non-equilibrium measurement performed in a microfluidic optical cell is presented. The inflection point of the optical transmission recorded during depressurization agrees well with the dewpoint pressure of the sample, determined by conventional laboratory techniques. With this new technique, a measurement can be performed in less than 5 min and requires far less than a milliliter of the sample. Benchmarking of this technique is presented using four retrograde condensate samples, which were created in the laboratory using multi-component compositions that are based on oilfield samples. Each sample was characterized at three different temperatures, and their maximum relative liquid volumes (maximum liquid volume/total system volume at the dewpoint pressure) ranged from 1.3% to 13.5% for these temperatures. The dewpoint pressure measured by this technique differs by no more than 100 psi from that measured in a conventional laboratory for samples of a richness of 4% or higher, while leaner samples display a difference of ∼200 psi.