This document describes methods to calculate estimated gas compressibility without having the full gas composition. The purpose of these methods is for use cases where reasonable accuracy is required but not critical and the methods must be computationally efficient such that they can be used in programmable logic controllers, remote terminal units, and supervisory control and data acquisition systems; akin to the functionality of the NX-19 or AGA-8 Gross methods but with higher accuracy.
Multiple simplified calculation methods were evaluated with one method performing significantly better than...
Multiple simplified calculation methods were evaluated with one method performing significantly better than the other methods. The best performing method was then tuned to better fit the reference data. The equations and associated source code for that method are contained as appendices in this report.
The methods discussed here were analyzed only with respect to the application to gas phase (including some supercritical conditions) natural gas with minimal helium, hydrogen, or hydrogen sulfide.
This version includes source code on the calculation method.