Drilling Rigs and Rig Types
How rotary drilling works, the parts of a rig, how the hoist is sized, the three offshore types and their water depths, and Türkiye's drillships.
A drilling rig is the integrated system of machinery used to bore a well. The steel tower, or derrick, is only the structure that carries the hoisting gear. The work itself is done by the drive system, the hoist and the mud circuit. Rigs are divided into land and offshore units, and offshore the water depth decides between the three main types: jack-ups, semi-submersibles and drillships.[1] Türkiye's fleet of six belongs to the last group.[2]
How Rotary Drilling Works
Oil and gas wells are almost always drilled by rotation. A bit on the end of a pipe string cuts or crushes the rock, turned either by a rotary table in the rig floor or, on modern rigs, by a top drive travelling up and down the derrick. A mud motor just above the bit can also spin it independently of the string, which makes directional drilling possible.[3]
Mud pumps meanwhile drive fluid down inside the pipe. It leaves through the bit and returns up the annulus, the gap between pipe and hole wall, cooling the bit and carrying the cuttings away.[1] At set depths drilling stops so that steel casing can be run and cemented. The stepped design of the well and the arithmetic of mud pressure are explained in the oil well article.
Main Parts of a Rig
Everything on a rig serves one of four functions: hoisting, rotating, circulating or controlling the well.
| Part | System | Function |
|---|---|---|
| Derrick and substructure | Hoisting | Carries the hoisting gear above and below the drill floor |
| Crown block | Hoisting | Fixed pulleys at the top of the derrick |
| Travelling block | Hoisting | Moving pulleys that raise and lower the string |
| Drawworks | Hoisting | Spool that reels the drill line in and out |
| Rotary table and kelly | Rotating | Pass rotation from the floor to the string |
| Top drive | Rotating | Modern alternative to the rotary table |
| Mud pump | Circulating | Forces drilling fluid through the system |
| Shale shaker | Circulating | Screens cuttings from the returning mud |
| Blowout preventer (BOP) | Well control | Seals the well at the wellhead |
Source: List of components of oil drilling rigs.[3]
When pipe is being pulled, the derrickman works from the monkeyboard, a catwalk about 35 to 40 feet above the floor, racking the top of each stand.[3]
Sizing the Hoist
What a rig must lift is set by the weight of the string. Take 3,000 m of 5-inch drill pipe at 19.5 lb/ft, about 29 kg/m. In air it weighs about 87 tonnes. Hanging in mud it weighs less, by a buoyancy factor of 1 − (1.30 / 7.85) = 0.834 for mud at a density of 1.30 and steel at 7.85, which brings the hook load to about 72.6 tonnes.
The block and tackle shares that load between the lines. With 10 lines carrying the block and friction ignored, the pull at the drawworks is about 7.3 tonnes. Real loads run higher once collars, heavy pipe and friction are added, and a stuck string needs extra pull on top of that, so rated capacity sits well above the calculated string weight.
Land Rigs
Small and medium rigs are mobile, mounted on trucks, tracks or trailers. Larger ones are broken into sections and loads for the move, which can take weeks.[1] On multi-well pads, walking rigs cut that time by shuffling from one well to the next on their own feet. An automated rig of this kind, built for long horizontal sections, costs about $25 million.[1]
Offshore Rigs
Water depth comes first, followed by sea conditions. Beyond about 520 m, drilling calls for a floating vessel.[4]
| Type | Station keeping | Water depth | Main trait |
|---|---|---|---|
| Jack-up | Legs on the seabed, hull lifted clear of the water | Generally under 120 m, premium units 150 to 190 m | Waves act on the legs and miss the hull |
| Semi-submersible | Floats on submerged pontoons, moored or on dynamic positioning | About 3,000 m for the sixth generation | High stability at sea |
| Drillship | Ship hull, dynamic positioning | About 3,000 m and beyond | Mobile, with large capacity |
Sources: Jackup rig, Semi-submersible platform and Drillship entries.[4][5][6]
Jack-ups
A jack-up has a buoyant hull and movable legs, and is usually towed to location. The legs go down, ballast weight drives them firmly into the seabed, and rack-and-pinion gear then climbs the hull up to an air gap above the waves. Most units have three or four legs.[5] They are the most numerous type of mobile offshore drilling unit.
Semi-submersibles
Most of a semi-submersible's buoyancy comes from ballasted pontoons below the surface, with columns holding the deck above the waves. The small waterplane area gives a gentle motion in a seaway, at the price of sensitivity to changing loads.[4] Blue Water Rig No. 1 worked in the Gulf of Mexico in 1961, and Ocean Driller, the first purpose-built drilling semi, was launched in 1963. Reach grew from about 200 m in the early 1960s to about 3,000 m for sixth-generation units built between 2005 and 2010.[4]
Drillships
On a drillship the derrick stands amidships over the moon pool, an opening through the hull. A marine riser connects the ship to the seabed, where the BOP sits on the wellhead and can be disconnected quickly in an emergency. Modern ships hold station on computer-controlled dynamic positioning without anchors.[6]
The water depth record has passed from ship to ship: Dhirubhai Deepwater KG1 at 3,107 m in 2011, Maersk Venturer at 3,400 m on Raya-1 off Uruguay in 2016, and Maersk Voyager, which went past 3,628 m on Ondjaba-1 off Angola in 2021.[6][7] Because the generators on a dynamically positioned ship run continuously, fuel use is high and supply vessels keep it topped up. The legal limits of offshore jurisdiction are covered under continental shelf.
Rig Counts
The industry tracks activity through Baker Hughes' count of active rigs. The international count, which excludes North America, stood at 1,079 in January 2026, and the US count at 558 on 22 May 2026.[8] The figures respond quickly to price expectations. They do not map directly onto output either, since a horizontal well opens far more reservoir per rig than a vertical one.
Türkiye's Drillships
With Yıldırım and Çağrı Bey, Türkiye's fleet has reached six. Reports based on energy ministry statements in March 2026 gave the following picture.[2]
| Ship | Joined the fleet | Assignment (March 2026) |
|---|---|---|
| Fatih | 2017 | Black Sea, Göktepe-2 and Eflani-1 |
| Yavuz | 2018 | Black Sea gas exploration |
| Kanuni | 2020 | Sakarya Gas Field |
| Abdülhamid Han | 2022 | Off Kocaeli, Kandıra-2 |
| Yıldırım | Seventh generation, recent addition | Black Sea |
| Çağrı Bey | Seventh generation, recent addition | Off Somalia, Curad-1 |
Maximum drilling depth is given as 12,200 m for Fatih, Yavuz and Abdülhamid Han and 12,000 m for Yıldırım and Çağrı Bey. That figure counts water and rock together and is no measure of water depth. Çağrı Bey left Taşucu on 15 February 2026, reached Somalia in April and moved to the Curad-1 location, with 288 days of work planned.[9] It is Türkiye's first deepwater drilling outside its own maritime jurisdiction.
Mining and Water Well Rigs
Oil is only one customer for drilling. Small augers can be carried by one person and serve water wells and ground work. Percussion drilling, which repeatedly drops a heavy tool, is one of the oldest methods of all. In mining, exploration holes locate and assess the ore, whereas production drilling is part of the daily cycle of the mine. Surface blast-hole rigs are split into small pre-split and large production machines, and underground mines have dedicated rigs for bolting and tunnelling.[1]
Two techniques dominate mineral exploration. Reverse circulation (RC) pneumatic drills took over most shallow work from roller bits in the 1970s. Diamond coring cuts out an intact cylinder of rock for the geologist, and the method has changed little since it was invented.[1]
A Short History of Drilling
The oldest known percussion wells were sunk in Sichuan under the Han dynasty, around 100 BC, reaching about 10 m. Chinese wells were down to 100 m by the 10th century and past 610 m by the 16th. Until internal combustion engines arrived in the late 19th century, rock was drilled with human or animal muscle.[1] Drake's 1859 well used small steam engines.[1]
The move to industrial scale is usually dated to Spindletop in Texas. It came in at 347 m on 10 January 1901, flowed for nine days before it was brought under control, and was estimated at about 100,000 barrels a day. The Hamill brothers, who drilled it, used a fishtail bit with circulating drilling mud.[10] At sea, the first drillship was CUSS I, whose design dates from 1955.[6]
The product itself is covered under petroleum. The fuels Bunkerist supplies are on the Fuel Oil and Gas Oil page.
Frequently asked questions
What is a drilling rig?
A drilling rig is the integrated system of machinery used to bore a well.
Is a drilling rig the same as an oil platform?
No. A rig drills the well and then moves on. A production platform stays in place for years and takes oil and gas from the wells.
What is the difference between a drillship and a semi-submersible?
A drillship has a ship's hull and is mobile with large capacity. A semi-submersible floats on submerged pontoons and is steadier in waves.
How many drillships does Türkiye have?
Six: Fatih, Yavuz, Kanuni, Abdülhamid Han, Yıldırım and Çağrı Bey.
How deep can a rig drill?
This depends more on well design than on the rig. Türkiye's drillships are rated to about 12,000 m in total, and the Chaivo well, announced as the world's longest, measures 15,000 m.
Sources
- Wikipedia. Drilling Rig. Used as a secondary source.
- Daily Sabah. Türkiye to Step up Black Sea, Somalia Drilling Operations in April, 30 March 2026 (with AA and the energy ministry).
- Wikipedia. List of Components of Oil Drilling Rigs. Used as a secondary source.
- Wikipedia. Semi-submersible Platform. Used as a secondary source.
- Wikipedia. Jackup Rig. Used as a secondary source.
- Wikipedia. Drillship. Used as a secondary source.
- gCaptain. Maersk Drillship Going for New Water Depth World Record off Angola, 22 October 2021.
- Petroleum News, report of the Baker Hughes international rig count, January 2026; Newsquawk, Baker Hughes US count, 22 May 2026.
- Marine Insight and Alomaliye. Reports on Çağrı Bey, February and April 2026 (energy ministry statements).
- Wikipedia. Spindletop. Used as a secondary source.
