Abstract
The use of surface gas measurements to identify oil and gas bearing zones has been in use since the 192001) Early well-site sampling methods were inaccurate and inconsistent, but had little effect on results since mea- surement and analysis techniques were equally poor. The introduction of gas chromatography in the 1950s created a demand for gas samples more representative of gas in the formation. New techniques were developed, but even these methods of continuous gas extraction at the well- site were recognized to be inconsistent, a fact noted in several publications at the time. However, the basic gas extraction system developed then is still in use in the field today.