STEAM-ASSISTED GRAVITY DRAINAGE.

Abstract

Heavy crude oil and bitumen are produced using the increased oil recovery technique known as steam-assisted gravity drainage (SAGD). A pair of horizontal wells are dug into the oil reservoir, one a few meters above the other. This is an advanced method of steam stimulation. In order to heat the oil and diminish its viscosity, high pressure steam is continuously fed into the upper wellbore. This causes the heated oil to drain down the lower wellbore, where it is pumped out. In the 1970s, Dr. Roger Butler, an engineer who worked for Imperial Oil from 1955 to 1982, developed the steam assisted gravity drainage (SAGD) method. Butler “invented the idea of developing certain bitumen resources thought to be too deep for mining utilizing horizontal pairs of wells and injected steam.”