# Natural Gas Density

## Definition - What does Natural Gas Density mean?

Natural Gas Density is the ratio of mass of gas to the volume of the confinement holding the gas. When natural gas is produced from different locations and reservoirs, it tends to have different compositions, i.e., its composition is not standardized, thus, a standard density value of natural gas is not possible to determine. This is the reason why the density of natural gas is given in a range of 0.7 to 0.9 kg per cubic meter.

## Petropedia explains Natural Gas Density

In order to find the density of natural gas, it is important to know the reservoir properties. Reservoir gas density is termed as the ratio of mass of gas to the reservoir volume. The natural gas is non ideal and thus, it follows a real gas law.

As per Real Gas Law PV = ZnRT.

Where:

P is the absolute pressure in Pascal;

V is the volume in cubic meter;

Z is the compressibility factor;

n is the number of moles of gas;

R is the gas law constant in J/(g mol-K) and;

T is the absolute temperature in Kelvin.

Thus, Density is expressed as : Where,

 mg = mass of gas, kg Ma = molecular weight of air Mg = average molecular weight of gas mixture yg = specific gravity for gas Pg = density of gas, kg/m3