What are different types of oil platforms

Question of the week: how do oil rigs work?


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Question of the week: how do oil rigs work?

Every week we answer your questions on all kinds of topics. Today Vivien R asks us: How do oil rigs work? Here's the answer ...

When oil was much cheaper than it is today, oil was only produced on the mainland. It was only after the oil crisis in the 1970s that the search for and extraction of oil was extended to the oceans.

What is an oil rig?

Oil rigs are artificial standing areas in the sea that are used to drill deep into the earth in order to extract oil or natural gas that is below sea level. This type of oil production in the sea is also called "off-shore extraction" (shore = shore, off-shore = "away from the shore").

What types of oil rigs are there?

There are five different types: the fixed drilling platform, the semi-submersible drilling platform, the flexible platform, the drilling ship and the jack-up drilling platform.

The fixed oil rig or fixed platform rests on one or more massive concrete or steel pedestals on the sea floor and cannot be moved.

A semi-submersible oil rig floats with the help of special floating bodies, so-called pontoons, and is therefore a very mobile type of oil rig. In order to pump oil safely in stormy weather conditions, the height of the platform can be adjusted. So that the semi-submersible rig remains fixed above the borehole, it is held in position by anchors and drives.

The flexible platform is a further development of the classic semi-submersible drilling rig and is also one of the mobile drilling rigs. It is held above the borehole by means of steel cables.

A drilling ship is a mobile drilling station in which a ship serves as a platform and whose propulsion system ensures that the ship maintains its drilling position and does not drift away from the sea currents.

Drill ships are often used for drilling in very deep waters up to a depth of 10,500 meters, in which normal drilling rigs cannot be attached.

The jack-up rig has vertically movable frame legs and is therefore one of the mobile drilling platforms. She is pulled to new locations with the help of tugs.

In general, mobile drilling platforms can be used in new areas after drilling, whereas the fixed drilling platform remains at its place of use until it is scrapped.

How does offshore funding work?

The part of an oil rig that lies above sea level is only a small part of the total structure. A drilling platform often protrudes hundreds of meters into the water.

The drillings go much deeper because the oil-bearing layer is far below the sea floor.

Directional drilling is often used to penetrate deeper layers of the earth. This involves drilling in several directions from one point so that a larger area can be developed.

The numbers on the drawing on the left mean:
1 platform,
2 top layer,
3 different holes,
4 oily layer

What tools are used to drill for oil?

Hollow bits are used for drilling so that the fine-grained rock particles, the so-called cuttings, that occur during drilling are transported to the surface. The drilling tool itself consists of a long tubular steel rod at the end of which the drill bit, i.e. the actual drilling tool, is located. Different bits are used depending on the hardness of the rock.

Once the drilling is complete, the oil is pumped up through kilometers of hoses. To this end, the drilling rig is often replaced by a pure production platform.

Problems of offshore drilling

Drilling at great depths can be very dangerous as it involves great risks. Major technical difficulties at depths far below sea level are very difficult to control.

Due to inadequate safety precautions, it has already happened that oil platforms have sunk, or oil has flowed into the sea in an uncontrolled manner through a so-called blowout, which has enormous environmental damage as a result.

Text: RR, as of: December 5, 2011, graphics: Marcin N (cc by sa 2.5), photos: Drilling ship, Blowout, Deepwater Horizon in Brand (US Coast Guard, PD), AgĂȘncia Brasil (drilling platform: cc-by- sa-2.5)

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