Drilling Rigs Types Chapter 4 PDF

2. Type of Drilling Rigs ▪ All rigs have the same basic components. ▪ Land rigs: jackknife or cantilever rigs and portable-masts. ▪ Main design features are portability and maximum operating depth. Derricks are built on locations. ▪ Marine (or offshore) rigs: bottom-supported o...

2. Type of Drilling Rigs ▪ All rigs have the same basic components. ▪ Land rigs: jackknife or cantilever rigs and portable-masts. ▪ Main design features are portability and maximum operating depth. Derricks are built on locations. ▪ Marine (or offshore) rigs: bottom-supported offshore rigs, semi-submersible floating rig, drill- ship floating rig. ▪ Main design features are portability and maximum water depth (WD) of operation.  Type of Drilling Rigs (ctd) Drilling Rigs Land Rigs Marine Rigs Heavy Land Rig Light Land Rig Floating Rigs Bottom Supported Rigs Helicopter Portable Rig Semi Submersible Platform Drill Ship Jackup Drilling Barge Submersible Type of Drilling Rigs – Land Rigs  Type of Drilling Rigs – Land Rigs The sequence of operations is as follows when a land well is drilled: ▪ Prepare location before rig arrives. ▪ Dig cellar ▪ Install conductor pipe ▪ Prepare support pad for rig, camp, etc ▪ Build roads, fencing, dig pits ▪ Sometimes drill water well. ▪ Move rig on to location, rig up and prepare to start drilling. A typical land drilling rig Type of Drilling Rigs – Land Rigs A typical swamp drilling rig Type of Drilling Rigs – Offshore Rigs Land Rig Platform Jack up Semi submersible Drill ship Tension leg platform Type of Drilling Rigs – Offshore Rigs  Type of Drilling Rigs – Offshore Rigs (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (1, 2) conventional fixed platforms; (3) compliant tower; (4, 5) vertically moored tension leg and mini-tension leg platform; (6) Spar ; (7,8) Semi-submersibles ; (9) Floating production, storage, and offloading facility; (10) sub-sea completion and tie-back to host facility. 16 Offshore Drilling Rigs ▪ Two main types: ▪ floating ▪ bottom-supported unit ▪ Floating unit include: semisubmersible (bottle- type, column stabilized), barge rig, and drill ship. ▪ Bottom-supported unit include: submersible (posted barges, bottle-type submersibles, arctic submersibles), jackups, and platforms. (1) Floating unit-Semi Submersible ▪ This floating drilling unit has columns when flooded with seawater, cause the structure submerge to a predetermined depth. ▪ Although it is moved by wave action, it sits low with a large part of its structure under water combined with eight huge mooring anchors, make it a very stable installation. ▪ This type of rig drills a hole in the seabed then it moves to the next location. Semi Submersible Semi Submersible ▪ With advancing technology some semi submersibles can drill in water depths over 5000 ft (1524 m). Semi Submersible Semi Submersible - Positioning Semi Submersible - Positioning Semi Submersible - Transporting Semi Submersible - Transporting Semi Submersible - Transporting (2) Drill ship (floating rigs) ▪ As the name suggests this is a ship shaped drilling vessel. ▪ Unlike the semi submersible and the Jackup, it does not require tugboats to tow it to location. ▪ Although they are not as stable as semi submersibles they also drill in very deep waters. Drill ship Japanese drill ship (VIDEO) (3) Drilling barges (floating rigs) A drill barge is simple a barge equipped for oil and gas drilling but compared to a drillship it does not have its own propulsion system and must hence be towed to the drilling site by other vessels. The drill barge is used in inland, shallow or smooth offshore areas where the water depth is typically less than 150 meters (< 492 ft). 31 FPSO ▪ Floating Production, Storage and Offloading System. ▪ They are attached to a seabed well head and they produce and store the oil until another tanker takes it from them. ▪ They are used to produce from small wells where it would be too expensive to build a platform. FPSO 34 FPSO OSX #1 at Rio de Janeiro Coast FPSO Crystal Ocean moored at the Port of Melbourne The circular FPSO Sevan Voyageur moored at Nymo 35 yard at Eydehavn, Norway (4) Platform (Bottom supported rigs) ▪ This immobile structure can be built from steel or concrete and rests on the seabed. ▪ When oil or gas is located, a platform may be constructed to drill further wells at that site and also to produce the hydrocarbon.  i. Steel Jacket Platform ▪ Most common type of platform. ▪ Consist of the jacket, a tall vertical section made of tubular steel members. ▪ Supported by piles driven into the seabed. ▪ Additional sections on top of the jacket provide space for drilling rig, crew quarters, and other equipments. Steel Jacket Platform  ii. Concrete Gravity Platform ▪ Build from steel reinforced concrete. ▪ Tall caissons, or column are the dominant feature of this platform. ▪ Sometime, special concrete cylinder are fixed at the base of the caissons on the sea floor A concrete platform is so heavy that to store crude oil. gravity alone is enough to hold it in place. 40 Concrete Gravity Platform iii. Steel-Caisson Platform ▪ Specifically for use in cold area – where fast-moving tidal currents carry pack of ice that can destroy steel-jacket. ▪ The caissons are made of two layers of thick steel to prevent ice damage.  iv. Compliant Platform ▪ Using rigid platform in water much over 1000 feet depth is not practical – very much expensive to build. ▪ In deep water, most companies use compliant platform, which contain fewer steel parts and are lighter than rigid steel-jacket. ▪ Guyed-tower platform and tension-leg platform. Guyed tower platform Tension Leg Platform (TLP) The relatively light weight jacket of Steel tendons are kept in tension by the a guyed-tower platform is supported buoyancy of the platform on a tension-leg by several guy wires & clump weight. platform.  (5) Jack up (bottom supported rigs) ▪ This is a mobile drilling rig, different from the semi submersible. Instead of floating over its drilling location the Jackup has long leg structures, which it lowers to and into the seabed raising the rig out of the water. ▪ The obvious limitation with this type of installation is the depth of water it can operate in. ▪ The maximum being five hundred feet. Jack up Jack up - Transportation  (6) Submersible (bottom supported rigs) 1. The submersible rig rested on the seafloor while drilling. 2. When ready to move, the worker removes the water from the compartment. This makes the rig floats. 3. Tugboat then tow the submersible rig to a new site. 4. Designed to drill at shallow water, about 175 ft deep (53 m). 5. Submersible has three types: Inland Swamp Barge, Bottle-Type, and Arctic submersible. 1 2 3 4. Drilling Procedure ▪ First, a surface pipe is set. A shallow hole is drilled of the several hundred feet deep. ▪ A string of surface casing is inserted into the hole and cemented in place. ▪ The surface casing is 10 to 20 inches in diameter, which allow the drill string and bit to pass through it for deeper drilling. ▪ After surface casing has been set, deeper drilling begins. A smaller bit is run inside the surface casing and continue drilling to the desired depth. ▪ The same process is repeated for intermediate and production casing. Drilling Procedure Casing strings cemented in the hole  Functions of Casing ▪ To keep the hole open and to provide a support for weak, or fractured formations. ▪ To isolate porous media with different fluid/pressure regimes from contaminating the pay zone. ▪ To prevent contamination of near-surface fresh water zones. ▪ To provide a passage for hydrocarbon fluids; most production operations are carried out through tubings inside the casing. ▪ To provide a suitable connection for the wellhead connection. ▪ To provide a hole of known diameter and depth to facilitate the running of testing and completion equipment.