Properties of Natural Gas

Treated natural gas consists mainly of methane the properties of both gases (natural gas and methane) are nearly similar. However, natural gas is not pure methane, and its properties are modified by the presence of impurities, such as N2 and CO2 and small amounts of unrecovered heavier hydrocarbons. 

Important properties of a representative liquefied natural gas mixture 

Natural gas is usually sold according to its heating values. The heating value of a product gas is a function of the constituents present in the mixture. In the natural gas trade, a heating value of one million Btu is approximately equivalent to 1,000 ft of natural gas. 

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Some environmentalists have also touted natural gas as a way station on the road to a hydrogen fuel (carbon dioxide-free) economy. As seen in Table 1, per unit of energy released, natural gas generates about 23 percent less carbon dioxide than gasoline and about 30 percent less than heavy fuel oil. This is helpful in reducing greenhouse emissions, but the other excellent properties of natural gas are even... 

The properties of natural gas are dominated by those of methane, notably a low maximum flame speed of 0.33 m/s. This strongly influences burner design, which must ensure that the mixture velocity is sufficiently low to prevent blow-off. Light-back , on the contrary, is very unlikely with such a low flame speed. 

The shaded areas in Figure 5-2 are based cm the properties of natural gas, a review of the current garage-related national codes, and other studies of gas releases in repair facilities. The codes where these recommendations appear include ... 

This chapter deals with macro-, meso-, and molecular-level thermodynamic and transport hydrate properties of natural gas and condensate components, with and without solute. The feasibility of using these tools to measure the kinetics of hydrate formation and decomposition are also briefly discussed, while the results of these measurements have been discussed in Chapter 3. The results for insoluble substances such as porous media are discussed in Chapter 7. 

Discusses the structural and physical properties of natural gas hydrates and compares these properties between different hydrate structures and ice... 

Brendeng, E. Grini, P. G. Jorslad. O. Melaaen, I. S. Maehlum, H.S. Owren, G.A. Puntervold, S. Measurement and Calculation of Thermodynamic Properties of Natural Gas Mixtures, NTNU-SINTEF 1993. 

Understanding the thermodynamics of natural gas is essential for optimizing the management of its resources. Correlation and prediction of thermodynamic and transport properties of natural gas are needed at different stages during the exploration and assessment of reserves as well as for its production, transport, and storage. 

We need to expand onr knowledge of the physical properties of natural gas, synthetic gas and the hydrocarbon constitnents of these gases. This knowledge mnst inclnde the influence of contaminants in various quantities, together with the impact of pressnre, temperatnre, etc. 

For the gas industry, the most important physical property of natural gas is its heating value. This value can be determined by calorimetry or by ealculating the value from a knowledge of the composition of the gas and the heating values of the prrre eorrrponents. Except for the most careful of calorimetric measirrements, the value obtained by calcrrlation is more accirrate. 

Sampling Method. The physical properties of natural gas in a sampling cylinder of constant volume are exactly described by the thermal equation of state. The mass in the cylinder can be calculated, if the pressure, the temperature and the composition of gas are known. Since the pressure and the temperature can be measured easily, the only unknown variable is the composition of gas for the calculation of the gas constant R and the compressibihty factor Z. The composition, however, varies only in a small range, so that an averaged value can be used for calculation. This favors the evaluation of the thermal equation of state as a very effective and precise tool in gas sampler technique. 

Basic Supervisory Control and Data Acquisition Systems (SCADA) Pressure testing for steel and plastic pipelines Hot tapping and stopping Characteristics and properties of natural gas Excavation safety Compressor operation Pipeline purging Valve maintenance Cathodic protection... 

Why do the physical properties of natural gas make it safer to use than most other fossil fuels ... 

The accurate prediction of thermodynamic properties of natural gas systems is of interest for gas industry. Compressibility factors are used in energy and flow metering. It is also used in calculations of gas pressure gradient in tubing and pipelines. When large volumes of gas are traded between produeers, distributors, and consumers, error in the estimation of the amount of involved are of real economic significance. In gas condensate reservoirs, well-productivity often declines rapidly when pressure drops below the dew point pressure near-wellbore. Therefore, it is very important to accurately determine the dew point pressure. The pressure and temperature of most natural gas mixtures can be found up to 150 MPa and 500 K, respectively (Nasrifar and Boland, 2006). At these eonditions, methane, ethane, and nitrogen are almost always supercritical while other hydroearbons are subcritical. Thus, the equation of state of natural gas mixture must be aeeurate at supercritical and subcritical behavior of methane and heavy hydrocarbons, respectively. 

Nasrifar, Kh. and Boland, O. (2006). Prediction of Thermodynamic Properties of Natural Gas Mixtures Using 10 Equations of State Including a New Cubic Two-Constant Equation of State. J. Petro. Sci. Eng. 51, 253. 

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