A rotary drilling rig works by rotating a drill string, which applies downward pressure to a drill bit that grinds the earth. Drilling fluid or air is pumped down the drill string to cool the bit, carry cuttings to the surface, and stabilize the borehole.
[pdf] Jackup rigs are so named because they are self-elevating with three, four, six and even eight movable legs that can be extended (“jacked”) above or below the hull. Jackups are towed or moved under self propulsion to the site with the hull lowered to the water level, and the legs extended above the hull. The hull is actually a water-tight barge that floats on the water's surface. When the rig reaches the work site, the crew jacks the legs downward through the water and int.
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Barge rigs work in shallower waters, usually less than 20 feet deep. After being floated to the drilling location, the hull is brought to rest on the ocean floor, creating a stable platform for drilling. Many barge rigs operate in the Gulf of Mexico and around the world. .
In waters too deep for a barge, but less than 50-70 feet deep, a submersible rig can be used. Columns or posts are submerged into the water and filled to specific levels that determine. .
As we move into deeper waters, a mobile platform called the “jack-up” rig comes into play. It gets this name because it can be moved directly over the location to drill or pump oil. The. .
Many offshore oil rigs are anchored platforms. They use a steel framework anchored to the ocean floor as a foundation for a surface drilling rig, equipment, and living quarters. Platforms may drill in many directions from this base, and they are broken down into specific types suited for various depths. .
In very deep water, it is not practical to attach an offshore rig to the bottom of the ocean. Floating oil rigs are kept in place by anchors or dynamic positioning systems that keep them over target. There are several types of floaters in use at various deep water drilling locations worldwide.
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