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The development of a single equation has simplified the planning of a two-dimensional well bore trajectory.
The basic relationship can be modified easily for the various types of directional and horizontal wells. The particular geometry of each type of well bore defines the variables used in the equation.
Directional drilling techniques have been used for many years to reach subsurface objectives overlain by inaccessible or difficult to reach surface locations. Economic and environmental considerations have increased the number of directional and horizontal wells drilled in recent years.
Drilling numerous wells from a single location can also greatly simplify the installation of gathering and production facilities.
Generally, horizontal and extended reach wells are drilled for economic reasons. These applications often involve consolidated, naturally fractured reservoirs where the well bore may intersect multiple fracture systems. Horizontal and extended reach wells have been drilled to reduce coning problems in reservoirs that have large gas caps or strong water drives.
In some reservoirs the horizontal well may improve drainage by increasing the area of the well bore in contact with the reservoir.
Deviating a well bore involves many factors that must be considered individually. Thus, careful planning is the key to successful directional drilling.
One of the first steps in planning a directional well should be the design of the well bore trajectory. Although drilling is a three-dimensional operation, many directional wells are planned in two dimensions, especially in the early stages of well planning.
Well bore trajectories can be categorized into two classes: the directional well and the horizontal well. Fig. 1 shows …