Chapter 8: Crude Stabilization

Introduction

The liquids that are separated from the gas stream during initial separation may be flowed directly to a tank or may be "stabilized" in some fashion. As was discussed in Chapter 2, these liquids contain a large percentage of methane and ethane, which will flash to gas in the tank. This lowers the partial pressure of all other components in the tank and increases their tendency to flash to vapors. Stabilization is the process of increasing the amount of intermediate (C ₃ to C ₅) and heavy (C ₆₊) components in the liquid phase. In an oil field this process is called crude stabilization and in a gas field it is called condensate stabilization.

In almost all cases the molecules have a higher value as liquid than as a gas. Crude oil streams typically contain a low percentage of intermediate components. Thus, it is not normally economically attractive to consider other alternatives to multistage separation to stabilize the crude. In addition, the requirement to treat the oil at high temperature is more important than stabilizing the liquid and may require the flashing of both intermediate and heavy components to the gas stream.

Gas condensate, on the other hand, may contain a relatively high percentage of intermediate components. Thus, some sort of condensate stabilization should be considered for each gas well production facility.

The most common method used to remove the light components from hydrocarbon liquids before the liquid enters a stock tank or a pipeline is...