According to the U. Natural gas is a fossil fuel formed when layers of buried plants and animals are exposed to intense heat and pressure over thousands of years. The energy that the plants and animals originally obtained from the sun is stored in the form of carbon in natural gas.
The actual drilling mechanism used to delve into the sea floor is much the same as can be found on an onshore rig. However, with drilling at sea, the sea floor can sometimes be thousands of feet below sea level. Therefore, while with onshore drilling the ground provides a platform from which to drill, at sea an artificial drilling platform must be constructed.
ChevronTexaco Corporation Drilling offshore dates back as early aswhen one of the first patents was granted to T. Rowland for his offshore drilling rig design. This rig was designed to operate in very shallow water, but the anchored four legged tower bears much resemblance to modern offshore rigs.
Since then, offshore production, particularly in the Gulf of Mexico, has resulted in the discovery and delivery of a great number of large natural gas deposits. The Drilling Template Since the land that is going to be drilled cannot provide a base for offshore drilling as it does for onshore drilling, an artificial platform must be created.
This artificial platform can take many forms, depending on the characteristics of the well to be drilled, including how far underwater the drilling target is. One of the most important pieces of equipment for offshore drilling is the subsea drilling template. Essentially, this piece of equipment connects the underwater well site to the drilling platform on the surface of the water.
This device, resembling a cookie cutter, consists of an open steel box with multiple holes in it, dependent on the number of wells to be drilled. This drilling template is placed over the well site, and usually lowered into the exact position required using satellite and GPS technology.
A relatively shallow hole is then dug, in which the drilling template is cemented into place. The drilling template, secured to the sea floor and attached to the drilling platform above with cables, allows for accurate drilling to take place, but allows for the movement of the platform, which will inevitably be affected by shifting wind and water currents.
In addition to the drilling template, a blowout preventer is installed on the sea floor. This system, much the same as that used in onshore drilling, prevents any oil or gas from seeping out into the water.
The marine riser is designed to house the drill bit and drillstring, and yet be flexible enough to deal with the movement of the drilling platform. Strategically placed slip and ball joints in the marine riser allow the subsea well to be unaffected by the pitching and rolling of the drilling platform.
Moveable Offshore Drilling Rigs There are two basic types of offshore drilling rigs: Moveable rigs are often used for exploratory purposes because they are much cheaper to use than permanent platforms.
Once large deposits of hydrocarbons have been found, a permanent platform is built to allow their extraction. The sections below describe a number of different types of moveable offshore platforms. A Drilling Barge Source: California Department of Transportation Drilling Barges Drilling barges are used mostly for inland, shallow water drilling.
This typically takes place in lakes, swamps, rivers, and canals. Drilling barges are large, floating platforms, which must be towed by tugboat from location to location. Suitable for still, shallow waters, drilling barges are not able to withstand the water movement experienced in large open water situations.
National Oceanic and Atmospheric Administration Jack-up rigs are similar to drilling barges, with one difference. This allows the working platform to rest above the surface of the water, as opposed to a floating barge. However, jack-up rigs are suitable for shallower waters, as extending these legs down too deeply would be impractical.
These rigs are typically safer to operate than drilling barges, as their working platform is elevated above the water level. Submersible Rigs Submersible rigs, also suitable for shallow water, are like jack-up rigs in that they come in contact with the ocean or lake floor.
These rigs consist of platforms with two hulls positioned on top of one another. The upper hull contains the living quarters for the crew, as well as the actual drilling platform.
The lower hull works much like the outer hull in a submarine — when the platform is being moved from one place to another, the lower hull is filled with air — making the entire rig buoyant.
When the rig is positioned over the drill site, the air is let out of the lower hull, and the rig submerses to the sea or lake floor.
This type of rig has the advantage of mobility in the water, however once again its use is limited to shallow water areas. Department of the Interior Semisubmersible rigs are the most common type of offshore drilling rigs, combining the advantages of submersible rigs with the ability to drill in deep water.
A semisubmersible rig works on the same principle as a submersible rig: The main difference with a semisubmersible rig, however, is that when the air is let out of the lower hull, the rig does not submerge to the sea floor.Plus, there's another incentive: Vehicles powered by liquefied natural gas, propane or compressed natural gas run cleaner than cars with either gasoline or diesel in the tank.
Nov 08, · News about Natural Gas (Fracking), including commentary and archival articles published in The New York Times. More News about natural gas and hydraulic fracturing, including commentary and.
This comprehensive overview details the potential environmental impacts of natural gas use and extraction, including its effects on water supplies, global warming emissions, air pollution, and wildlife.
The drilling and extraction of natural gas from wells and its transportation in pipelines results in the leakage of methane.
The correct answer is: b. seismic surveys When it comes to natural gas drilling and identifying proper locations, researchers and experts determine the right places through the process of seismic surveys/5(8).
Like all forms of energy drilling, natural gas drilling starts when a deposit of natural gas is found deep beneath the Earth’s surface.
To find these deposits, energy company scientists use a variety of methods. Natural Gas. When first obtained from the ground, natural gas is composed of primarily methane with other alkanes typically mixed in, and possibly also carbon dioxide, nitrogen, and hydrogen sulfide.
Shale gas, specifically, is natural gas trapped within shale geologic formations (a type of sedimentary rock).