ON RULES OF THUMB

A volume of 1 m3 of gas has a mass of 1 kg

The heating value of 1 kg of natural gas is equal that of 1 kg of any liquid hydrocarbon.

The net heating value is 90% of the gross heating value.

Remember that hydrate forms even at 15 C (at 70 bar)

Molecular sieves are too good for drying gas to pipeline specification.

Methanol is too expensive for CONTINUOUS hydrate inhibition as it is difficult (read expensive) to recover.

Many people confuse glycol injection (for hydrate inhibition) with glycol drying (in an absorber column). In both cases there will be glycol regeneration. Different glycols are used in different concentrations.

Many people confuse gaslift with gas injection. Gaslift gas comes back instantly while gas injected stays in the reservoir for years (you hope).

Do not recover liquid hydrocarbons by processing gas that will be used as gaslift gas.

It does not make sense to compress gas to subsequently put it through an expander from the start of a project. There may be a case in year 18 when the pressure has come down below the minimum required to run the existing expander plant.

Many people would like to recover liquid hydrocarbons from a high pressure natural gas by cooling only without reducing the pressure ("NOT TO WASTE PRESSURE!!"), but they forget that they may not enter the phase envelope and therefore produce no liquid at all.

It makes a lot of sense to put high pressure gas through an expander, knock out the heavier hydrocarbons and subsequently compress it using the same expander as driver for part of the compression.

Liquid hydrocarbon recovery by lean oil absorption is PAST.

Liquid hydrocarbon recovery by silicagel adsorption is PAST.