Horizontal and extended-reach wells are making an important contribution to world's oil production. Well over five thousands horizontal wells and drainholes have been drilled, with approximately fifteen hundreds such wells in Canada. Horizontal wells can be valuable under certain conditions, as discussed in this paper, but they are not necessarily always better than vertical wells. Horizontal well drilling and production technologies, with particular emphasis on their application in naturally fractured reservoirs, are considered in light of the North American and European experience.
The paper also discusses the current trends in horizontal well drilling, production and completion. The increasing use of coiled tubing, multilaterals drilling and underbalanced drilling are described. While horizontal wells are an important development, some care should be exercised in planning afield using horizontal wells, in particular with regard to the subsequent application of secondary recovery methods.