Learn The Basic About Drilling Rig Types from VDO Training Plus Transcript

This is another training VDO that is very good for entry level personnel who are working in the oilfield industry especially drilling part. This VDO will give the over view regarding rig types and their applications.

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VDO Transcript

Drilling rigs like these bore or drill holes into the earth. Usually they drill to find oil and gas. They work both on land and offshore. Some are big and some are relatively small. Big rigs drill very deep holes, 20,000 feet, 7000 m or more.

Small rigs may only drill to a few thousand feet or meters. People in the oil industry group rigs into six basic types;

• land

• Jack up

• platform

• submersible

• semi submersible

• drill ship

I land the rig drills on dry land. They are the most, and rig. Light duty rigs drill holes from about 3000 to 5000 feet deep or 1000 to 1500 m.

Medium duty rigs drill to depths ranging from about 4000 to 10,000 feet or 1200 to 3000 m.

Heavy duty rigs drill holes from about 12,000 to 16,000 feet deep or 3500 to 5000 m.

Ultra-heavy duty rigs drill holes from about 18,000 to 25,000 feet or more; 5500 to 7500 m or more.

Crewmembers can move land rigs on trucks, tractors, trailers, barges, helicopters, heavy rolling gear, skids and in rare cases, on specialized air pressurized equipment. Small, light duty rigs are pretty simple to move. Ultra-heavy land rigs can be difficult to move. Jack up rig drills offshore wells. It has legs that supports and beck and hull.

When positioned over the drilling site, the bottom of the legs rest on the seafloor. Jack up rigs can drill in water depths ranging from a few meters or more than 400 feet to 120 m. Boats tow Jack up rigs to a location with its legs up. Once the rig up crew gets the legs firmly positioned on the bottom of the ocean, they can adjust and level the deck and hull height.

A platform rig, is an immobile off shore structure that is, once built, it never moves from the drill site. Companies drill several wells from the platform. Platform rigs can be Tender assisted rigs. The Tender floats next to the rigid platform which is firmly pinned to the seafloor. Many platform rigs do not have a Tender, they are so large that they are self-contained.

Big platform rigs include the Steel Jacket Platform, the Caisson Type and the Concrete gravity type. In Deepwater, rig builders have to build platforms that yield to water and wind movements. Two compliant platform rigs are; the Guyed –Tower and the tension leg.

A submersible rig rests on the seafloor when it is drilling. Workers flood compartments that cause the rig to submerge and the rest on the bottom. When ready to move, workers remove the water from the compartments. This makes the rig float, boats can then tow the rig to the next site.

Rig builders design submersibles to drill on shallow water and in water that is up to 175 feet deep, a little over 50 m.

Submersible drilling rigs include; Posted Barge Submersible, Bottle Type submersible, and the Arctic Submersible. A semisubmersible drilling rig is a floating offshore drilling rig. It has pontoons and columns. When flooded water, the pontoons cause the unit to partially submerge to a predetermined depth. The working equipment is assembled on deck. On the site, workers can either anchor the drilling rig to the seafloor or use a system of thrusters and positioners to keep the rig over the hole. Here, they have it anchored. Crewmembers mount the well-head and blowout preventers on the ocean floor. Special hollow pipe called riser pipe, connects the top of the blow out preventer to the rig.

In some cases the crew uses thrusters to keep the rig over the hole called dynamic positioning. The thrusters, which are connected to an onboard computer, keep the rig in position. Some dynamically positioned semi- submersibles can drill in water depths of more than 7500 feet or over 2200 m.

When keeping a rig over the hole, crews use the term On Station. Here is a semisubmersible rig loaded on a special carrier. Carrier vessel is moving the rig over a far distance over the ocean. For short-term moves, the rig owner tows the rig to the drill site or some semi-submersibles are self propelled.

A drill ship, is a self-propelled floating offshore drilling unit. It usually uses a Sub-Sea blow out control unit similar to the one on a semi submersible.