Below are some examples of reasons for directional or horizontal drilling (and Horizontal Directional Drilling).
a. Inaccesible Location Drilling
Some of the reservoir with the conditions on the surface that does not allow to do the drilling straight / vertical will be very suitable for being directional or horizontal drilling (and Horizontal Directional Drilling). This technique is one of the directional drilling technique most commonly performed to achieve a layer that can not be achieved in the usual way, for example reservoir that lies beneath the city, under the agricultural land / plantation, etc. Figure 3.7. show formations under so do urban or horizontal directional drilling (and Horizontal Directional Drilling).
Figure 3.7. Formation in the Lower City
b. Multiple Well Drilling
When a drilling location has limited areas on the surface so it is not possible to do a lot of drilling wells with a different layout. This can be overcome by drilling multiple wells. Namely drill at one location with a lot of well made, for it was performed or horizontal directional drilling (and Horizontal Directional Drilling) .Multiple well drilling is often performed on offshore drilling from a single platform or from a remote place. Figure 3.8. shows a platform that does Multiple well drilling.
Gambar3.8. Multiple Well Drilling
c. Salt Dome Drilling
In areas that are found salt dome (salt dome) that is located above the oil reservoir, drilling straight / vertical impossible. Because when drilling to penetrate the salt dome (salt dome) will cause serious problems, especially the occurrence of blow out so we need a directional or horizontal drilling (and Horizontal Directional Drilling) which shall be led directly to the oil reservoir.
Figure 3.9. The salt formation under the Dome
d. Side Tracking or Straightening
Sometimes in performing drilling operations straight / vertical an extremely severe deflection occurs so away from the target, making it necessary to realign the wellbore. For tracking is done side by pengeburan directed. Or in instances where fish that can not be removed and buried dilubang drill, drilling should avoid these fish so that the drilling equipment is not broken then do side tracking.
e. Relief Well Drilling
In the event of a well blow-out, one way to overcome them is by drilling a relief well or make. Relief well is a well made adjacent to the well blow-out with the aim to drain the fluid resulting blow out so that it can be controlled. Usually the relief well is done with directional or horizontal drilling (and Horizontal Directional Drilling).
Figure 3.10. Relief Well Drilling