Directional drilling
（重定向自Slant drilling）
![A horizontal directional drill in operation](/Images/godic/202502/11/Ditchwitch_jt4020_mach10327.jpg")
![Screenshot of a structure map generated by contour map software for an 8500ft (2600 meter) deep gas & oil reservoir in the Erath field, Vermilion Parish, Erath, Louisiana. The left-to-right gap, near the top of the contour map indicates a fault line. This fault line is between the blue/green contour lines and the purple/red/yellow contour lines. The thin red circular contour line in the middle of the map indicates the top of the oil reservoir. Because gas floats above oil, the thin red contour line marks the gas/oil contact zone. Directional drilling would be used to target the gas and oil reservoir.](/Images/godic/202502/11/Contour_map_software_screen_snapshot_of_isopach_map_for_8500ft_deep_OIL_reservoir_with_a_Fault_line0327.jpg")
Directional drilling (or slant drilling) is the practice of drilling non-vertical wells. It can be broken down into three main groups: oilfield directional drilling, utility installation directional drilling (horizontal directional drilling), directional boring, and surface in seam (SIS), which horizontally intersects a vertical well target to extract coal bed methane.