In SAGD operations, steam is injected into the ground through an injector well to heat bitumen to make it more mobile (less viscous) and can then be extracted through a producer well. Both wells must be “pre-heated” before they can be used – a process which can take three to five months. The injected steam loses heat as it travels down the well to the bitumen-bearing zone. Additional steam is typically injected to make up for this heat loss, but Vacuum Insulating Tubing (VIT) technology helps to reduce the need for adding additional steam.
VIT consists of two concentric, tubing strings. The air between the tubulars is removed, creating a vacuum layer that is difficult for heat to move across. Therefore, vacuum insulated tubing greatly reduces the amount of heat that a well loses to its surroundings above the bitumen-bearing zone.
By reducing heat loss, less natural gas is burned to heat water to make steam. This reduces greenhouse gas emissions. Additionally, because not as much steam is needed to soften the bitumen, the amount of water used is also reduced. Tests to date suggest wells equipped with vacuum insulated tubing may need as little as 75 days of “pre-heating,” reducing the time, fuel and water required for wells to start producing bitumen (compared to the traditional three to four month time frame for pre-heating ).
The trialing of VIT and its eventual commercial application was completed through the Surmont joint venture project between ConocoPhillips Canada and Total E&P Canada.