Jay D. Stafford, National Tank Company
Stage separation as applied to oil production is a process in which the oil and gas mixtures, flowing from producing wells, are separated into liquid and vapor phases by two or more equilibrium flashes at consecutively lower pressures. The ideal method of separation, to retain the maximum amount of fluid flowing from an oil well, would be that of true differential liberation of the gas by a steady decrease in pressure from that existing at the well head to the atmospheric, or near atmospheric, pressure maintained in the storage tanks. With each differential decrease in pressure, the gas evolved would be immediately removed from the crude oil from which it is being separated. To carry out such a differential process would be impractical. A very close approach, however, towards differential liberation of gas can be accomplished by putting the mixture of oil and gas through several series connected separators, in each of which flash vaporization takes place. In this way the maximum economical amount of liquid flowing from the well can be retained in the stock tanks. The application of the process of stage separation, indeed, offers to the oil producer a means of increasing ultimate oil or distillate recovery, and also increasing revenue from property now in operation.