increasing concern about environmental impact, directional wells are often used
for infill drilling. In contrast to traditional vertical wells, directional
wells use a slanted or curved (deviated) wellbore. More than one directional
well can be drilled from a common drilling pad.
drilling, which extends the wellbore into a much larger portion of the
oil-bearing formation, has been employed since the late 1980s to improve
production and enhance recovery. Horizontal drilling increases production rates
by contacting more reservoir. This increases oil recovery and may reduce the
amount of water and gas mixed with the oil. Environmental impacts are reduced
because fewer well sites are needed.
techniques also make it possible to drill a number of horizontal offshoots from
a single, vertical, directional or horizontal wellbore. This is called
multiple entry and has proved useful in many types of oil and gas formations.
Petroleum Communication Foundation. Our Petroleum Challenge: Exploring Canada's Oil and Gas Industry, Sixth Edition. Calgary: Petroleum Communication Foundation, 1999. With permission from the Centre for Energy.