Views: 0 Author: Site Editor Publish Time: 2023-05-11 Origin: Site
Oil wells are holes drilled in the earth to bring petroleum hydrocarbons to the surface.Often some natural gas is released with the oil as associated petroleum gas.A well designed to produce only natural gas may be referred to as a gas well.Wells are created by drilling down into oil or gas reserves, which are then fitted with extraction devices, such as pump rigs, that allow extraction from the reserves.Drilling a well can be an expensive process, costing at least hundreds of thousands of dollars, and in hard-to-reach areas, such as when building offshore oil platforms, the cost is much higher.The modern drilling process began in the 19th century but became more efficient with the advancement of oil rigs in the 20th century.
Oil wells are often sold or exchanged as assets between different oil and gas companies in large part because a well may not be producing during a period of falling oil and gas prices, but if prices rise, even low-producing ones Wells may also have economic value. In addition, new methods such as hydraulic fracturing (a process in which gas or liquid is injected to force the production of more oil or gas) have made some wells viable. However, peak oil and climate policies around fossil fuels have made those wells and expensive technologies increasingly rare.Yet a large number of neglected or poorly maintained wellheads is a big environmental problem:They can leak methane emissions or other toxic emissions into local air, water or soil systems.This pollution often gets worse when wells are abandoned or abandoned wells that are no longer economically viable or maintained by companies.A 2020 Reuters estimate suggested at least 29 million abandoned water wells worldwide are a significant source of greenhouse gas emissions that drive climate change.
The well is created by drilling a hole 12 centimeters to 1 meter (5 inches to 40 inches) in diameter in the ground using a drilling rig that rotates a drill string with a drill bit. After the hole is drilled, a section of steel pipe (casing) with a diameter slightly smaller than the drilled hole is placed into the hole.Cement can be placed between the outside of the casing and the borehole known as the annulus. Casing provides structural integrity for newly drilled wellbores, in addition to isolating potentially hazardous high-pressure areas from each other and from the surface.Since these areas are safely isolated and the formation is protected by the casing, the well can be drilled deeper (into potentially more unstable and violent formations) with a smaller drill bit and also with a smaller size casing. Modern wells typically have 2 to 5 sets of subsequent smaller sized holes drilled into each other, each set cemented with casing.
To drill the well
The bit cuts into the rock with the help of the weight of the drill string.There are different types of drill bits; some cause the rock to disintegrate through compression failure, while others cut fragments from the rock as the bit turns.Drilling fluid, also known as “mud,” is pumped inside the drill pipe and out the drill bit.The main components of drilling fluid are usually water and clay, but it also often contains a complex mixture of fluids, solids and chemicals that must be carefully adjusted to provide the correct physical and chemical properties needed to safely drill wells.The special functions of drilling mud include cooling the drill bit, lifting rock cuttings to the surface, preventing rock instability in the borehole wall,and overcoming the pressure of fluids inside the rock to keep these fluids from entering the wellbore.Some oil wells are drilled with air or foam as the drilling fluid. When the drilling fluid is circulated back to the surface outside the drill pipe, the resulting rock "cuttings"are swept away by the drilling fluid.The fluid is then passed through a "shaker" which filters out cuttings from the high quality fluid that is returned to the pit. Observing flowback cuttings for anomalies and monitoring pit volume or flowback rates is imperative to catch "blowouts" early. A "kick" is the formation pressure at the depth of the drill bit greater than the hydrostatic head of the mud,which, if not temporarily controlled by closing the blowout preventer and eventually by increasing the density of the drilling fluid, will allow formation fluids and soils to flow uncontrollably Come up from the ring space.
The pipe or drill string to which the bit is attached is gradually lengthened as the well deepens by screwing in an additional 9 m (30 ft) section or pipe “joint” under the kelly or top drive.This process is called establishing a connection.The process known as "tripping" involves pulling the bit out of the hole to replace the bit (tripping) and returning it with a new bit (tripping).By creating a bracket with multiple joints, joints can be combined to more efficiently trip out when pulling out of a hole.For example, a traditional triple unit pulls three joints out of the hole at a time and stacks them in the derrick. Many modern rigs, known as "super singles," lift and unload pipes one at a time, placing it on racks as they go.This process is all facilitated by a rig that contains all the necessary equipment to circulate the drilling fluid, lift and turn the pipeline, control downhole, remove cuttings from the drilling fluid, and generate on-site power for these operations.