2. Horizontal
We can divide horizontal wells into three general categories, based on their curvature from vertical to horizontal:
Short radius: with the radius R = ft (DLS = 180 – 30 deg/100ft)
Medium radius: with the radius R = ft (DLS = 30 – 6 deg/100ft)
Long radius: with the radius R = ft (DLS = 5 – 3 deg/100ft)
These categories are starting points for designing the well completion.

3. Horizontal
Short radius wells have curvature radii of less than 50 ft, and as low as 30 ft. Their buildup angles are consequently very large — as much as 180 degrees per 100 ft [ rad/m]. With current technology, it is not possible to run casing or measurement-while- drilling (MWD) tools in these sections. Hole diameters are limited to a maximum of about 6 1/4 inches.
Medium radius wells have curvature radii ranging from 200 to 1000 ft, and buildup angles of between 6 and 30 degrees/100 ft. These wells can be logged and cased. Hole diameters are limited to approximately 12 3/4 inches.
Long radius wells use standard drilling equipment to attain build angles of 3 to 5 degrees per 100 ft. This configuration is becoming commonplace, with lengths of 3,500 ft now considered routine, and sections approaching 20,00ft being reported as of 1996.

4. Horizontal
Stimulation and completion needs, more often than not, point towards long-radius wells.
Of the three configurations, we should therefore consider long radius first (keeping in mind that we might want to limit the length to better manage the well).
We should consider short radius second, for multiple horizontal completions and, in enhanced recovery applications, for injection/production configurations. Medium radius wells represent an intermediate option, and are relatively less common.

5. Horizontal