Text 9 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

well walkways quarters

platform platform

Figure 9.1 Offshore platform layout.

9.2 Comprehension questions:

1. Where are multiple directional wells drilled?

2. What are several well platforms connected by?

3. Why is it desirable to separate wells and the personnel? Why are they combined into a single platform in the deep water?

4. Are emulsion problems not severe in the process of the oil, gas, and water separation?

5. Is it important to remove all traces of oil from the produced water?

6. What kind of the dehydration system is normally used offshore?

7. Why is the produced gas dehydrated?

8. What is pumped into a pipeline to shore?

9.3 Give Ukrainian correspondences:

deep water; well jackets; three-phase pipeline; walkway; quarters platform; two-phase flow.

9.4 Make 3 sentences using the above mentioned words.

9.5 Make all possible questions:

The single platform is inherently less safe than separate platforms, but there is no other possibility in places like the North Sea, where a single platform can cost well over a billion U.S. dollars.

9.6 Translate into Ukrainian:

1. Natural gas serves a relatively local market, while crude oil is a worldwide commodity. This is because natural gas cannot be shipped around the world in conventional marine tankers.

2. Oil wells are typically produced at capacity because there is a ready market somewhere in the world for all the crude that can be produced.

3. Sea-going vessels, temporarily anchored in place, are increasingly being used in place of permenent platforms.

9.7 Retell Text 9

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