There are four main types of well completions: conventional single zone, conventional multiple zone, tubingless, and horizontal/multilateral. Conventional single zone can be open hole or cased hole. Open hole completions have casing set above the pay zone and the pay zone is drilled without casing. Cased hole completions run casing through the pay zone and then perforate. Conventional multiple zone completions isolate multiple pay zones using a dual packer and separate tubing strings. Tubingless completions perforate zones without running production tubing. Horizontal/multilateral wells extend the wellbore horizontally or in multiple directions within the pay zone.