Obtaining and utilizing a truly representative gas analysis is critically important in developing accurate volume and energy measurement data and, ultimately, determining the value of natural gas. Empirically, we’ve found that errors associated with gas sampling and analysis are paramount among the most common sources of natural gas orifice measurement error. One way to improve this statistic is to employ sampling methods that will produce representative gas quality data. There are many factors which are fundamental to proper sampling, including using a sample probe located in the center-third of the pipe, avoiding liquid contamination, and using stainless steel cylinders. Among our industry’s most common sampling methods are the following:
(Click on one of the sampling methods above to see a photo and expanded description.)
Which method you use depends upon the stream characteristics as well as the delivery volumes. In general, the more liquefiables that the gas contains, the more likely its composition can change significantly over a short period of time. Any process that alters one or more components of the gas, such as sweetening or dehydration, may require a better quality determination method for accurate measurement. Choosing a gas sampling program to meet your goals can often be a difficult decision, especially with widely varying gas prices. As a result, you may need to routinely re-evaluate your measurement policies.