The composition of gas from the wellheads in different gas fields varies, and the composition of the gas from different wellheads within the same gas field can vary. Different compositions have different characteristics of combustion. As a result, the gas from one source may be acceptable for use but the gas from a different source may not be acceptable. Heavier hydrocarbons such as pentane and butane can cause detonation and other problems. For these reasons, a fuel analysis is required to determine if the fuel is acceptable for a particular Cat engine.
Note: The composition of the gas from a field can change over time. Allow some adaptability for this change during the life of the project.
Some gas fields contain significant amounts of hydrogen sulfide. In these cases, follow the precautions that are recommended in this Special Publication, "Sour Gas" topic.
The site may have equipment such as scrubbers, liquid separators, and heat exchangers that remove water and liquid hydrocarbons from the gas. However, vapor can still be drawn into the engine. The maintenance costs are variable for engines that use wellhead gas. Sometimes, overhauls are needed at intervals that are sooner than the expected time. However, the practices and factors at many sites enable overhaul intervals that are longer than the expected times: efficient preventive maintenance, proper engine oil, and operation below the rated load.
Follow the guide for fuel usage that is in the Engine Performance publication. These publications are available from your Caterpillar dealer.
Consult your Caterpillar dealer before operating the engine with fuel that has hydrocarbons that are heavier than butane.
Note: Use the Cat Methane Program, LEKQ6378 to determine if the fuel is suitable for the particular engine application.