Email Document Reference

Enter your email address below and the reference for this document will be sent to shortly from webmaster@ceesi.com.

Title: Uncertainties In Natural Gas Properties Determined By Gas Chromatography
Author: Darin L. George
Source: 2008 Natural Gas Sampling Technology Conference
Year Published: 2008
Abstract: Natural gas is bought and sold based on the energy flow rate through the gas pipeline, typically in millions of BTUs per day. The energy flow rate is determined from two quantities, the standard volumetric flow rate of the gas and the energy content of the gas stream. Volumetric flow rates are measured by ultrasonic meters, orifice meters, or turbine meters, while the energy content of natural gas is commonly determined through an analysis of the gas stream by a gas chromatograph (GC) located in the field, or perhaps a laboratory GC analysis of a gas sample taken from the pipeline. Natural gas transmission companies are continually working to accurately measure volume flow rates and reduce lost-and-unaccounted-for gas volumes that can impact custody transfer. Correct GC analyses are also crucial to accurate custody transfer and sales of natural gas. However, GC users may not understand how errors in calibration, sample mishandling, or fluctuations in GC performance can affect the energy flow rate determined for the gas in the pipeline. This paper will discuss several sources of uncertainty in GC analyses, including uncertainties in gravimetric calibration standards, chromatograph repeatability, and effects of sample distortion. The paper will then give examples of how these uncertainties can propagate into computed gas properties used in custody transfer, particularly heating values and energy flow rates. Identifying these sources of uncertainty and quantifying their impact can allow natural gas companies to find and minimize the largest contributions to error, improve the confidence in custody transfer by all parties involved, and avoid disputes between those involved in natural gas transportation and sales.

In order to prevent spam and automated file downloads for documents within the Measurement Library, please follow the instructions below and then you will be able to email a reference to this article.