CompressorTechTwo - 2010 (Sample)

Flow diagram of an associated gas recovery unit.

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suitable for this kind of service are oil-injected screw compressors. Being volumetric compressors, they are not affected by gas composition (variation in molecular weight) and are able to maintain a constant delivery pressure.

These compressors are usually dri-
ven by electric motors, but the ten-
dency is to use gas engines as dri-
vers since the gas is always
available. Enerproject has also manu-
factured modules with diesel en-
gines, but this solution has to be
considered an exception.

It is important to maintain the skid size in standard container dimensions for transport into remote areas. The modules are positioned on a concrete foundation near the wellhead. Usually three or four modules are placed in parallel. The number of modules in operation is selected according to the associated gas flow, which is continuously variable.

The delivery pressure of the associated gas recovery module is set according to the use. If the gas is used as turbine fuel gas, the delivery pressure can be in the range of 435 to 580 psi ( 30 to 40 bar). The gas needs to be very clean after compression to comply with the strict gas turbine manufacturer specifications.

More often the module supplies the gas to a low-pressure local gathering line at 87 psi ( 6 bar) or 290 to 362 psi ( 20 to 25 bar) depending on the gathering system. The gas collected from several wells in the neighborhood is then piped to a refinery or other uses.

According to Enerproject, this type of production now accounts for 40% of its total order volume. Due to the environmental protection issues, associated gas orders are increasing more than the orders for fuel gas skids. ;