Choosing the Right Drilling Rig

Drilling type Soil type Comments

Rotary drilling

For more information, please visit JK Drilling.

Soft rock Significant depths up to 5,000 meters
Possibility of inclined or horizontal drilling Down-the-hole drilling Hard and cracked rock (limestone, granite, etc.) Depth up to 4,000 meters Top hammer drilling Consolidated land Small diameter (150 mm maximum), shallow depth
Able to do inclined drilling Auger drilling Clay, clayey sand, gravel Depth of a few dozen meters

Core drilling

All soil types Drilling for soil analysis
Able to do inclined drilling Percussion drilling Hard rock: sandstone, limestone, shale Depth up to 100 meters Pipe Jacking Clay, clayey sand, gravel Installation of horizontal or vertical pipes

 

Rotary drilling: This type of drilling digs a hole by grinding the rock with a tool under the effect of weight and rotation. It is mainly used in oil production. The cuttings are brought to the surface under the pressure of a drilling fluid that is injected into the drill string. Drilling fluid also helps consolidate the walls of the borehole, so it is not necessary to case it as the operation progresses.

Down-the-hole drilling (rotary percussion drilling or rotary hammer drilling): this type of drilling uses drilling rigs that drill with a rotary cutter (drill head) and hammer the bottom of the hole with a pneumatic hammer. The excavated material rises to the surface under the pressure of the compressed air used for the hammer. These drilling rigs are powerful and have high drilling rates, especially in rock. For artesian wells (wells where water naturally rises to the surface under groundwater pressure) or geothermal drilling, an air injection at the end of the drill pipe pushes the water up the borehole, allowing the operator to immediately determine the water flow encountered. This type of drilling is used for hard and cracked ground up to 4,000 meters deep. When the drilling bit is eccentric, the drilling can be done with a casing advancement system (installation of tubes by gravity) which reinforces the hole as the drilling progresses.

Top hammer drilling: this type of drilling uses drilling rigs that also operate on a percussion system, but one that remains outside the borehole. They are mainly used for small diameter drilling, for example for mineral exploration or the installation of tie rods in rock. This system is used for shallow boreholes, as there can be significant deviation due to the structure of the ground drilled through. These drilling rigs can operate in any direction however.

Auger boring: This is a type of rotary drilling using a worm screw (the auger). This type of drilling is mainly used for unconsolidated clay or sand terrain. The excavated material is directly brought to the surface by the worm screw. For deep drilling, it may be necessary to regularly raise the auger to empty it of its excavated material.

Core drilling: Core drilling is similar to rotary drilling, but it uses a crown to extract a sample, called a core, inside the tool.

Percussion drilling: consists in breaking the rock by dropping a tool, the drill bit, by gravity. This type of drilling can only be used vertically. To prevent the borehole from collapsing, it is necessary to case it as it is drilled. The cuttings are reassembled as soon as they interfere with drilling by replacing the drill bit with a flap valve bailer. The flap valve bailer is a type of tube equipped with a tilting flap in the lower part. This tilting flap allows the tube to be filled with excavated material which is then transported to the surface.

Pipe jacking: is mainly used to install horizontal pipes. The tube is pushed progressively by percussion, the excavated material being removed at the end of the drilling operation either by water injection or with an auger. This technique is used in particular to avoid transmitting vibrations to the surrounding buildings or to avoid digging a trench.

There are many types of offshore platforms used for oil and gas drilling and exploration. Some of these are fixed to the ocean floor and others are floating platforms or vessels. Each is designed for different water depths and purposes. Some floating production systems may include storage or refinery facilities and employ hundreds of maritime workers.

There are 5 main types of drilling platforms, each with several unique variations.

 

#1 Barge Rigs

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.

 

#2 Submersible Rigs

In waters too deep for a barge, but less than 50-70 feet deep, a submersible rig can be used.

If you are looking for more details, kindly visit Crawler Mounted Pneumatic Tophammer Drill Rig.

Columns or posts are submerged into the water and filled to specific levels that determine their depth. Drilling equipment on the platform above drives a floating drill unit below.

#3 Jack-Up Rigs

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 rig can be self-elevated (jacked up) from the bottom of the ocean floor to secure it in place. Jack-up rigs are well suited for shallow waters of 400 feet or less.

There are two types of jack-up rigs:

• Cantilevered Jack-up, with a drilling derrick mounted on an extending arm
• Keyway or Slot Jack-up, which has a drilling unit on the platform over an opening it drills through

#4 Platform Rigs

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.

Fixed Platforms

Fixed platforms are made of steel or cement and are intended to be permanent structures. They house large facilities, heavy equipment, and big crews. Most are located on the continental shelf in deep water up to feet.

They can drill directionally with a radius of up to five miles. The platform is held in place by large steel or concrete legs that attach to the ocean floor.

Compliant Towers

When the oil or gas is even deeper, from up to feet, a compliant tower may be used. These structures are made of concrete and steel and are tall and narrow. They are intended to flex and sway with the wind and waves.

Up to feet, they attach firmly to the sea bed, but, for greater depths, a tension leg platform may be used. These towers are technically floating platforms that are secured with a series of anchors and cables. They are fixed but also floating, and they can reach depths of feet.

 

#5 Floating Rigs or Floaters

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.

Semi-Submersible Platforms

For deeper waters up to 12,000 feet, the preferred method of exploration and drilling is to use semisubmersibles or drill ships. Semisubmersible work-decks float on top of the water, while the vast majority of their mass is contained below the water to help stabilize the platforms and keep them in place. As a result, the deck is rather stable and well-suited for drilling in rough waters -10,000 feet deep. However, semisubmersibles are not easily moved.

Two notable types of semi-submersible rigs include:

• Sea Star Platforms, which use flexible steel legs rather than anchors, usually in less than feet of water.
• Spar Platforms, which sit on a hollow cylinder that hangs below the water at a depth of approximately 700 feet. This stabilizes the platform, allowing drilling up to 10,000 feet.

Drill Ships

For new exploration and the drilling and capping of new wells, drill ships are typically used. Drill ships have the drilling equipment installed directly on the deck, typically in the middle of the deck. The well is drilled through the &#;moon pool,&#; an opening in the center of the ship. They are kept in place by dynamic positioning.

 

Worker Safety on All Oil Rigs

Working on any vessel or platform rig carries with it certain risks. Owners and operators of rigs need to take steps to help protect their workers and provide safe working environments. In the event they are negligent and workers are injured, they can be held accountable under maritime law.

If you are an oil rig worker, seaman, or vessel worker and have been injured while in the service of a vessel or ship, you could be entitled to monetary compensation. To find out more about your legal rights and if you have grounds for a personal injury lawsuit or &#;maintenance and cure,&#; contact the Jones Act attorneys at Schechter, Shaffer & Harris, L.L.P.

For more DTH drill pipesinformation, please contact us. We will provide professional answers.