The drilling industry

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GET TO KNOW THE INDUSTRY

Using a drill to reach reservoirs of fossil fuels is a simple concept that has been known since the 19th century. The practical challenges are enormous, however, and they have never been greater, as energy companies increasingly look offshore and towards deeper waters to help fuel modern society.

Exploration and Production Companies (like BP, Chevron or Statoil) usually contract specialised drilling companies like Maersk Drilling to make wells. Drilling beneath up to several kilometres of pitch-dark ocean is a formidable task – but a task that Maersk Drilling is known for handling with world class safety and effectiveness.


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Maersk Drillings expertise lies in the following dark blue areas

THE PHASES OF DRILLING

The drilling process begins when researchers from an energy company identify a potential undersea oil deposit. Drilling rights are then obtained to the site to prepare it for exploratory drilling.
PHASE 1: EXPLORATION

Maersk Drilling sends a mobile drilling platform to the site to obtain a core sample, which geologists analyse for signs of petroleum. The exploratory drilling rig will typically drill several temporary wells, each taking a few months to complete. A positive find (called "a show") is followed by more exploratory wells to verify the quality before taking next step: Drilling the much more elaborate production well.


PHASE 2: DRILLING BEGINS

A drill bit is attached to a "drill string" made of segments of drill pipe, each about nine meters long. The drill bit is lowered into the sea – sometimes to a depth of several kilometres – until it meets the seabed. The drill is rotated by a turntable at the platform floor, and as the drill grinds its way downwards (sometimes horizontally as well) extra lengths of drill pipe are attached.

For cooling, cleaning and stabilising pressure, a "drilling fluid" is pumped through the drill pipe and out through nozzles in the drill bit at high velocity. The fluid is usually a mixture of water, clay, barite and chemicals. Back at the platform, the fluid is recycled through a circulation system that disperses the crushed rock and reuses the fluid.


PHASE 3: FINALISING THE WELL

When the drill reaches target depth, production casing is lowered into the well and cemented into place. At the bottom, small explosive charges make small holes that allow the oil or gas to flow into the well while controlling pressure.

Once a well is "live", the drilling rig is typically replaced by a production platform, assembled at the site using a barge equipped with heavy lift cranes. An average well can last decades, so offshore production platforms are built with a long stay in mind.


REGARDING SAFETY AND THE ENVIRONMENT

Maersk Drilling aims for the highest possible well control standards. If the drilling releases pressurised oil or gas, the ‘Blowout Prevention System’ kicks in: Hydraulically operated valves and other closure devices seal the well and directs the pressurised fluids from the well and into specialised pressure controlling equipment.

Water is a common companion of oil in reservoirs. As oil is drawn from a deposit, it is often necessary to separate the two substances. The water is cleaned and pumped back into the ocean after processing. Great emphasis is placed on ensuring that the water returned to the ocean is as free from oil and chemicals as possible and strict regulations apply.

The people handling the hardware are making the real difference

Maersk Drilling rig types

The most important type of rigs all has different characteristics:
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Jack-ups 

Are the most common type of offshore drilling rig, and tend to be the most volatile in terms of rates and demand. Jackups have a barge section that floats on the water (and holds the drilling equipment) and multiple legs (typically three, but sometimes more) that extend down to the sea floor. Jackups are typically towed to the targeted drilling site and, upon arrival, the legs are jacked down to the sea floor. 

Once in place, these platforms are typically steady and sturdy, with a drilling platform well above the waves. Because they do physically touch the bottom of the sea floor, they are generally only usable in relatively shallow water – up to around 400 feet of water. Most jackups drill down through holes in the platform, but some (called "cantilevered") drill over the side of the barge.


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Semisubmersibles 

Are quite a bit different than jackups. Semisubmersibles float on submerged pontoons and have an operating deck that is well above the surface. Below the surface are anchors and umbilicals that essentially tie the rig in place, though some do have powered systems that can help keep the rig on target. 

With succeeding generations, the capacity of these rigs has increased, and the most modern generation of semi-submersibles can operate in up to 10,000 feet of water. While jackups can earn high day rates in specific circumstances, semisubmersible rates tend to be three- to five-times higher.


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Drillships

Like semi-submersibles, drillships can operate in a wide variety of circumstances, and are often used in locations with very deep water. Like semi-submersibles, drillships typically have an operating limit of 10,000 feet – a limitation that has more to do with extending a drilling operation through that much water as opposed to any limitations of the ship itself. 

Drillships basically look (and operate) like very large boats, with drilling taking place through a hole in the hull (called a moon pool). These ships are completely independent and self-powered. While not as stable as semisubmersibles, drillships are mobile and can carry a lot of equipment – making them a good option for drilling exploratory wells. Like semisubmersibles, day rates for drilling ships are often quite a bit higher than those for jackups.