Deeper water, moderate sea states

In deeper water, individual well jackets become too costy, so multiple directional wells are drilled from a single well platform.

Several well platforms are connected by three-phase (oil, water, and gas) pipelines to a facilities platform where processing takes place. If the field’s location is far offshore, a quarters platform is also installed.

Wells, facilities and quarters are kept on separate platforms if possible, although they may be tied together by walkways. This is a safety measure reflecting that fired processing facilities have the highest risk of all offshore facilities. It is therefore desirable to separate the wells and the personnel from this risk as much as is possible.

The following operations take place on the facilities platform (Figure 9.1):

– The oil, gas, and water are separated. Since offshore crudes generally have relatively high API gravity, emulsion problems are usually not severe. Horizontal, three-phase separators, therefore, work quite well.

– All traces of oil are removed from the produced water, which is dumped overboard into the sea.

– The produced gas is dehydrated to avoid hydrates, and compressed into a pipeline to shore. Liquid glycol dehydration systems are normally used offshore.

– The crude oil is pumped into a pipeline to shore. If the same pipeline is used for both gas and oil, two-phase flow will be present.

As the water gets deeper and platform jackets get more expensive, operators must forego the luxury of separate well, facility, and quarters platforms. Instead, the three functions are combined into a single platform, which also functions as a drilling platform in the early stages.

Form

wellwalkways quarters

platformplatform