The wellpath is defined by a survey which gives the positions of the well at a number of points along the wellbore.
The position is defined with the co-ordinates in the North, East and Vertical directions (N,E,V). In addition Along-Hole Depth (AHD), inclination and azimuth of the survey station are included as most surveys measure inclination and azimuth to calculate the co-ordinates. Inertial Navigation Systems measure the co-ordinates directly and calculate the inclination and azimuth..
The location of a wellhead is given as co-ordinates . . .