eng Oriental Scientific Publishing Company Biosciences Biotechnology Research Asia 0973-1245 2016-06-10 11 Spl.Edn.1 221 229 10.13005/bbra/1414 11832 article B. Antony Fayaz 1 Huda 1 Asif Ali 1 BE (Petroleum Engineering) AMET University, Chennai - 603 112, India. Directional drilling is a wellbore along a predetermined trajectory to intersect a designated subsurface target. Directional drilling has a long and interesting history. However, it has only been in the past ten years that much of the new innovative technology has been introduced to meet the challenges of onshore and offshore developments.A typical directional well starts off with a vertical hole and the bottom holes location may end up hundreds or thousands of feet or meters away from its starting point. With the use of directional drilling, several wells can be drilled into a reservoir from a single platform.During the past years many innovations have taken place, including computerized well planning, more use of down hole motors and turbines, techniques to drill horizontal wells and the introduction of Measurement While Drilling (MWD).Directional drilling has now become an essential element in oilfield development, both onshore and offshore. It has made great advances over a relatively short period of time.This work deals with different applications of directional drilling and the deflection techniques used in deviation of the well. Three types of well profiles have also been studied with the designing of BHA (Bottom Hole Assembly) and the synchronization of MWD (Measurement While Drilling) with directional drilling. https://www.biotech-asia.org/vol11_nospl_edn1/directional-drilling-in-l-profile/ Directional drilling; Onshore; Offshore development