Drilling Rig Types

Although this section of our website is devoted to the offshore exploration and drilling activities, this short article is here to cover the major types of oil rigs in general.

Oilfield drilling is, when it comes down to bare essentials, a question of “drilling a usable hole” in the ground. And, in turn, usable hole is commonly characterized by being a hole in the ground that lives up to the requirements of the well-plan and includes benchmarks for production, cost and lifespan.

The main pieces of equipment required to drill a hole in the ground is collectively known as a drilling rig. Drilling rigs are classified according to what the rig is supposed to be standing on when it drills and how it is moved around. The main media to stand on is land and water.

It is pretty simple, but that is how it is.

Land rigs are made for working on solid ground where no special requirements are necessary except the area to be flat and of a certain size. All other rigs are made for working either over water or floating in the water. There are barges and jack-up type rigs which are made to stand on the seabed on the bottom of the water and/or swampland and marshes, and there are semi submersibles and drill ships that float in the water. Each type will be described separately on the next pages. It is important to notice that in general, the main drilling equipment on all these rigs are the same. The difference is how it moves and where the drilling location is situated.

There are other sub-types of drilling rigs that are not specifically described here. These rig types include:

• Heli-Rigs, or Helicopter transportable land rigs, these are made mostly of aluminum,

• Dedicated coiled tubing rigs,

• Slanted drilling rigs, used for the Slant hole drilling,

• HDD, utility drilling rigs, normally hydraulic-driven,

Most of them use the same type of equipment to drill and most of the processes are very similar with the exception of coiled tubing drilling systems.

In this lecture on drilling equipment, the focus will be put on the drilling rig and its related equipment. The method of drilling the hole is subject for a different lesson.

Some types of equipment are used on all types of rigs, basically the drilling equipment, and other equipment is rig type-specific, i.e., to be able to compensate problems inherent in the rig design or use.

When looking at different drilling rig types and different locations around the world, all drilling rigs consist of the same basic equipment with the same functions, all over the world. A giant concrete platform rig in the North Sea area with 800 people onboard is essentially doing the same as a humble land rig in east Texas. The same types of equipment and people perform just about the same jobs. Of course, the food is more readily available on the big platforms and they have galleys, television rooms and many other recreational facilities to keep the crew occupied while waiting to go back to work.