No one really knows how oil is formed, but geologists have many theories. They believe that it comes from the remains of tiny plants and animals which have been buried under sediments for millions of years. Heat and pressure slowly convert these remains into oil before they are again exposed to the surface by tectonic activity.
The equipment used for drilling oil wells is called “drilling rigs .” The basic types are the land rig, which stands on legs that reach into the ground; water rigs, which are placed on piers above bodies of water; and ice rigs, which are used in winter to drill through rivers or lakes.
Most of the world’s highest-producing wells are in Saudi Arabia. The Ghawar field is one of the world’s largest known oil fields, with an estimated 45 billion barrels (7×10 m³) in reserve. It is said to contain more petroleum than any other known group of oil fields, worldwide; there may be larger individual oil fields elsewhere (such as Burgan Field in Kuwait), but they do not approach Ghawar in aggregate potential. The Safaniya Field, by contrast, is the largest offshore oilfield, with more than 25 billion barrels (4×10 m³) in reserve.
The tools used to locate oil reserves and plan wells include seismography, reflection seismology, and surface geophysical surveys. Geologists also monitor oil well drilling by logging the sounds made by different types of drills, which vary according to the amount of rock they are cutting through; core samples; and chemical analysis.
Once the oil has been located in a prospect, the company must determine whether it is commercially feasible to drill there. One way to accomplish this is to estimate how much oil underlies the surface of the prospect area, based on geological information. The company must then estimate how much oil can be recovered from this reserve. This is an important step in determining whether to drill because there are many dry wells that are not commercially viable.
The actual drilling of an oil well begins with the arrival of a “drilling rig.” These rigs vary in size, power, and the depth of the hole they drill. Generally speaking, larger rigs are capable of drilling deeper holes. They can drill a narrow passageway for hundreds of feet down to the oil bearing layer before widening it into a larger well. This is called ” making a well .”
The types of drilling rigs used today range from those that use cables and pulleys to drill shallow wells to those that can drill down 30,000 feet (9,100 m) deep. Drilling a well is expensive because it requires moving heavy machinery into remote locations and operating complex machinery under difficult conditions. The cost for an offshore oil platform can run as high as $60,000 a day.
In addition to drilling rigs that can drill very deep holes, there are some rigs that can operate in water as deep as 10,000 feet (3,000 m). These drilling ships use huge containers called “moon pools” on their decks to hold the space open for workers and machinery to work below deck. The moon pools are covered by steel plates called “moon pool doors.”
In conclusion, drilling for oil is very difficult to do, but once all the problems are over, it’s worth it in the end.