Page 648 - Air and Gas Drilling Manual

12-12 Air and Gas Drilling Manual
Ambient Air In
Primary Water Oxygen Out
Filter
Compressor(s)
Oxygen
Hydrocarbon Filter
Filter
Air Cooler Membrane
Particle
Filter

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Booster
Compressor

Mist Pump

Inert Air
Into Standpipe
Figure 12-4: Schematic of location plan utilizing membrane filter unit [1].

12.3.2 Membrane Unit Efficiencies
It is not necessary for these membrane filter units to filter all the oxygen from
the atmospheric air in order to render the injected drilling gas inert to downhole
hydrocarbon ignition. Filtering oxygen down to approximately five percent (by
volume) of the resulting gas will make the gas inert [2, 3]. When the membrane
filter units were introduced, Burlington Resources Incorporated (San Juan Division)
carried out field tests to evaluate the efficiency of the units. Figure 12-5 gives the
approximate results of these tests. Thus, if the drilling operation requires that the
oxygen content in atmospheric air be reduced to approximately five percent (by