This method significantly reduced the footprint of natural gas development within the campus area. Over a 25-year lifetime, the wells are expected to produce a total of 110 billion cubic feet of gas. In 2010, the University of Texas at Arlington was featured in the news for drilling 22 wells on a single drill pad that will drain natural gas from 1100 acres beneath the campus.

This method has been used to reduce the surface footprint of a drilling operation. See graphic (A) - at the top of this page - to learn how the Pittsburgh International Airport will be paid $500 million for their gas. This reservoir might still be tapped if the drilling pad is located on the edge of the property and the well is drilled at an angle that will intersect the reservoir. Sometimes a reservoir is located under a city, airport, or park where drilling is impossible or forbidden. These six purposes are described below and graphically illustrated by the six drawings on this page.Ī) Hit targets that cannot be reached by vertical drilling. Horizontal drilling has been used for many purposes, which include:Ĥ) improve production in fractured reservoirs Examples are the Marcellus Shale of the Appalachian Basin and the Bakken Formation of North Dakota. When horizontal drilling is combined with hydraulic fracturing, some rock units which were unproductive when drilled vertically can become fantastic producers of oil or natural gas. In these cases, an ability to accurately steer the well in directions and angles that depart from the vertical is a valuable ability. However, drilling horizontally or at an angle other than vertical can obtain information, hit targets, and stimulate reservoirs in ways that cannot be achieved with a vertical well. If the dogleg impairs the well, remedial action can be taken, such as reaming or underreaming through the dogleg, or even sidetracking in extreme situations.Most wells drilled for water, oil, natural gas, information or other subsurface objectives are vertical wells - drilled straight down into the earth. Sixth, excessive doglegs increase the overall friction to the drillstring, increasing the likelihood of getting stuck or not reaching the planned total depth. Fifth, a relatively stiff bottomhole assembly may not easily fit through the dogleg section drilled with a relatively limber BHA. Fourth, casing successfully cemented through the dogleg may wear unusually quickly due to higher contact forces between the drillstring and the inner diameter ( ID) of the casing through the dogleg. Third, repeated abrasion by the drillstring in a particular location of the dogleg results in a worn spot called a keyseat, in which the bottomhole assembly components may become stuck as they are pulled through the section. Second is the possibility that a planned casing string may no longer easily fit through the curved section. First, the wellbore is not located in the planned path. There are several difficulties associated with doglegs. In surveying wellbore trajectories, a standard calculation of dogleg severity is made, usually expressed in two-dimensional degrees per 100 feet of wellbore length. While a dogleg is sometimes created intentionally by directional drillers, the term more commonly refers to a section of the hole that changes direction faster than anticipated or desired, usually with harmful side effects. A particularly crooked place in a wellbore where the trajectory of the wellbore in three-dimensional space changes rapidly.

Oilfield directional drilling