The first multilateral well was drilled in 1953 at Bashkiria field, Bashkortostan Republic, Russia. Multilateral drilling helps increase wellbore contact with hydrocarbon-producing zones by branching multiple extensions off a single borehole. As of 2013, the world's longest ERD well is the 12,345-m well drilled from Sakhalin Island, Russia, to the offshore Odoptu field. Operators have used ERD to access offshore reservoirs from land locations, sometimes eliminating the need for a platform. Previously unreachable reserves have become accessible and economical to produce.ĭirectional drilling includes three main specialized applications: extended-reach drilling (ERD), multilateral drilling and short-radius drilling. Today, operators use sophisticated drilling assemblies to drill complex geologic structures identified from 3D seismic data. By the 1930s, a controlled directional well was drilled in Huntington Beach, California, USA, from an onshore location to target offshore oil sands. Directional drillers used rudimentary survey instruments to orient the wellbore. The first intentionally drilled directional wells provided remedial solutions to drilling problems: straightening crooked wellbores, sidetracking around stuck pipe and drilling relief wells to kill blowouts (see Figure 1). The same techniques were later employed to deliberately deflect the well path to intersect hard-to-access reserves. ![]() ![]() To combat this deviation, drillers devised techniques to keep the well path as vertical as possible. ![]() These methods alerted drillers to the fact that supposedly vertical wells were actually deflecting in unwanted directions. The practice of directional drilling traces its roots to the 1920s, when basic wellbore surveying methods were introduced.
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