| Oil wells usually refer to a vertical hole drilled in the | | | | Oil wells can be drilled onshore or offshore. Onshore |
| earth to find and extract petroleum oil and natural gas | | | | wells are found on land, and are easier and less costly |
| from the underground layers. Wells are generally | | | | to drill and operate. Gas as the byproduct of oil |
| composed of a series of small holes and tubing and | | | | extraction can also be efficiently carried away through |
| smaller holes within, encased in cement, whereby | | | | pipe lines. Off shore wells target oil which is |
| perforations along the casing in the production zone | | | | underground but also found under an ocean, away |
| enable the oil to flow though rocks into the production | | | | from land and shores. Shallow waters are easier to drill |
| casing. Inherent pressure is then enough to allow the oil | | | | into and operate wells on, whereas the logistics of the |
| and gas to flow to the surface. In case the pressure is | | | | procedure become more complicated and expensive |
| not enough, other substances may be injected to | | | | the deeper the water is. |
| stimulate it. | | | | Oil wells can be classified in different categories, |
| Wells can produce three types of products. Some | | | | according to their purpose. Production wells are drilled |
| produce only oil. Others produce both oil and natural | | | | for oil production. Appraisal wells are used to assess |
| gas. Others produce only natural gas. However, | | | | characteristics of a hydrocarbon accumulation. Wildcat |
| wherever there is extraction of oil, there are high | | | | wells refer to wells dug in an area where not much is |
| chances that there will also be natural gas present, as | | | | known of hydrocarbon accumulation, and referred |
| in the release of hydrocarbons when the oil is | | | | much to a random dig. These are not really used |
| extracted. Where demand for gas is present in the | | | | nowadays, since they were used for exploratory and |
| area of the drilling, pipes conduct the gas to the supply | | | | information purposes, which is now available through |
| lines. In places where the gas may not be carried | | | | the efforts placed in exploratory and appraisal wells. |
| away for use, it used to be burnt. However recent | | | | Regardless of the classification, is it these wells that |
| environmental concerns have reduced this occurrence | | | | help us to enjoy the standard of living that is far above |
| of burning gas on the spot, and the gas is often | | | | what was known as the norm even fifty years ago. |
| re-injected in the well to produce pressure. | | | | |