Oil and gas are hugely valuable resources that power not only our cars, cities, and homes, but major economies around the world. Today I will discuss the mechanics of the oil drill, used to extract oil and natural gases from beneath the earth’s crust.
Offshore and onshore rigs operate similarly, though the former are configured to allow drilling in a marine environment as opposed to land. Both have the same major function: to create holes in the earth’s subsurface in order to extract and process oil and gas. Though some rigs are operated manually (these are called augers), most are massive structures with dozens of important parts.
The rig itself has many components that support drilling and extraction. Most oil rig systems consist of large diesel engines, which power the electrical generators, which in turn power the mechanical drilling system. The mechanical system is supported by the derrick, a tall support structure which holds the drilling apparatus and allows new sections of pipe to be added during the drilling process. The rig also has a blowout preventer, a valve that relieves pressure and prevents gushing; a mud pit, pump and pipe which store and circulate fluids; and a drill string, which contains the drill collar and bit. Most rigs also have hoisting systems to lift heavy loads.
So, what’s the drilling process itself like?
First, a surface hole is drilled. The drill bit, collar, and drill pipe are placed into the hole, just above where the oil is thought to be located. When the turntable (which drives the rotation motion) and the kelly (a pipe attached to the turntable) are fastened, the drilling can begin. As the drilling progresses, mud is circulated through the pipe and out of the bit to float rock cuttings out of the hole. As the hole gets deeper, new joints of pipe are added. The pipe, collar and bit can all be removed when a pre-set depth is reached.
Casing pipes are then placed into the hole to prevent it from collapsing, and cement is pumped through and allowed to harden. The entire process (drill, pipe, cement) is repeated until the piping reaches the well’s final depth.
At this point the drilling apparatus is removed so the crew can test for oil, which they do by examining formation, pressure, and rock samples. If they confirm their findings, a perforating gun is lowered into the depth of the reservoir to create holes in the casing through which oil can enter. Tubing is run into the hole as a conduit for the oil to flow through, with a device called a packer used to seal it. A multi-valved structure called a Christmas tree (pictured on the left) is connected to the top of the tube and casing to control the oil flow.
Lastly, special fluids are pumped down to pressure the reservoir rock into releasing the oil flow. The crew puts a pump on the wellhead, and a gear head moves the lever up and down to create suction. The oil obtained is known as crude oil, which is refined to get a final commercial product.
Originally published on RezaMostafaviTabatabaei.net
Reza Mostafavi Tabatabaei is an entrepreneur, investor, activist and international business man who specializes in oil and gas industry. He currently serves as the president of a Dubai-based company, which provides a comprehensive range of products and services in Engineering, Procurement, and Drilling operations for onshore and offshore undertakings.