In order for oil and gas reserves to reach the market, minerals rights are leased to oil companies through a legally binding contract. At times, mineral rights leasing might include the drilling of an extended reach well. This could be beneficial to the land owner because less surface drilling space is used, smaller holes mean generating less waste, less noise and extended reach wells are kinder to the eco-system.
While there is still a lot of flexibility regarding the definition of an extended reach well, the most commonly accepted term is that the horizontal depth must be twice the length of the vertical depth (2:1). Another acceptable definition is a well that exceeds 4500 feet in length. An extended reach well can also be defined as a well that drills in deep water or through salt, even if the well ratio does not meet the 2 to 1 standard. The advantage of an extended reach well is that it can acquire greater drainage through fewer locations, reach deposits far away from the rig, drill where other rigs might not be able to be placed, increased reserve potential and deferred abandonment.
The extended reach well was created in the 1980’s. Mobile Oil was the first to experiment with this type of well. The longest extended reach well on record is one located in Russia that measures a depth of 41,667 feet and a horizontal measurement of 38,514 feet.
Extended reach wells are more costly than standard wells and are a challenge when it comes to directional drilling. Hole cleaning is an issue, as well as managing the mechanical loads on the drill string and downhole pressure. These types of wells also demand extra planning, but are beneficial in reducing overall environmental impact, which can be important with mineral rights leasing.
Additional benefits of extended reach wells include the ability to reach a large area from just one surface drilling location, and productivity and drainage can be maximized by keeping the well in a reservoir for a longer distance.
Extended reach wells have progressed to the point where new technologies have emerged that stretch the current boundaries. One method is called the Reelwell Drilling Method, where the distance of a current well of this type is multiplied.