Tuesday, February 17, 2009

Oil and Gas Processing (Oil Section)

Figure 1: Typical PFD of Oil and Gas Processing
The typical process flow diagram (PFD) of oil and gas processing for most of fixed or floating offshore production. Two sections consists crude oil stabilisation and associated gas compression.

Crude oil stabilisation section is processing the crude oil with export oil specification. The common export oil specification are true vapour pressure (TVP 100 kPa @ 50ºC) or reid vapour pressure (RVP 7psia @60ºF) and water content; basic sediment and water (BS&W) maximum at 0.5 vol%.

Typical arrangement of crude oil separation and stabilisation are; 3 Staage Separator (HP-MP-LP Separators) and Electrostatic Coalescer. An Inlet Heater is required at upstream of HP Separator. The outlet temperature is above emulsion breaking temperature to increase oil and water separation. The HP Separator separates oil, water and gas with 3-5 minutes residence time. The recommanded operating pressure for separators are: 10 bara (HP), 4.5 bara (MP) and 1.5 bara (LP)


Figure 2: Horinzontal 3-Phase Seaprator

The HP Separator, 3 phases (oil, water and gas) separation, horinzontal vessel with wier. Separation of oil from water relies on specific gravity. The gas goes to compression train, the water goes to Produced Water System, and the oil goes to Interstage Heater.

Interstage Heater further is heating oil to above wax dissolve temperature 75ºC. The oil send to MP Separator for further oil, water and gas separation. The oil send to LP Separator.

LP Seaparator stabilises oil as per requirement of TVP. The LP Separator may operates as 2 phase or 3 phase separation due to low water content in oil.

The oil from the LP separator is pumped via a low shear pump to the coalescer. The coalescer removes remaining water content in oil.

The BS&W and salt content of the oil is managed by the removal of produced water at each stage of the process and by the coalescer. The stabilised and dried crude then flows to the production tanks, via a crude cooler.

You may interest:
Oil and Gas Processing (Gas Section)

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