Slant drilling is a non-vertical form of well drilling typically used in natural gas and oil production. This form of drilling is generally for extracting oil or gas resources that cannot be accessed through traditional vertical drilling. Slant drilling is also employed as a means of protecting sensitive areas of the environment such as wetlands and oceans. This directional drilling also helps to reduce the number of wells and equipment needed for natural gas and oil production. In some cases, slant drilling provides pressure relief when a vertical well malfunctions.
Natural gas and oil reservoirs are sometimes located beneath inaccessible areas such as lakes, mountains, glaciers, or residential areas. Rather than disturbing the existing landscape, a well is drilled at a 30-45 degree angle to tap into the reservoir from another location. Vertical well production of underground reservoirs can sometimes be very difficult due to their shape. In these instances, slant drilling is required for more efficient removal of oil and natural gas.
Slant drilling also provides many environmental benefits by allowing natural gas and oil production to take place away from delicate ecosystems. This type of drilling is especially important in protecting the marine environment near offshore reservoirs. Slant drilling can allow a single offshore drilling rig to gain access to more than 20 wells. This production arrangement reduces the total number of drilling rigs operating in a single body of water and can minimize the risk to the marine environment.
Allowing multiple wellheads at a single offshore location can also help to reduce the overall cost of oil and natural gas exploration. The need for fewer drilling rigs has helped to reduce the costs associated with natural gas and oil production in offshore locations. Onshore production expenses have also been reduced by allowing drilling rigs to be placed in locations that are more easily accessible to vehicles and pipelines. Production costs can be further reduced by permitting crews to bypass dense, rocky soil by drilling non-vertical wells from a location with fewer obstructions.
Slant drilling can also be used to relieve pressure after a well blowout occurs. In this situation, an alternative well is drilled at an angle to the original well from a different location. The angled well relieves the pressure and stops the uncontrolled flow of oil or natural gas at the site. This relief well is then used to pump cement into the original well to cap it off until repairs can be made. This method of stopping leaks is particularly useful in offshore situations.