SAGD, an acronym for Steam-Assisted Gravity Drainage, refers to an advanced thermal recovery technique used in the extraction of heavy oil or bitumen from oil sands deposits. It involves injecting steam into a reservoir formation to heat the highly viscous oil, reducing its viscosity and allowing it to flow more freely for recovery.
In SAGD, pairs of horizontal wells are drilled into the oil sands. One well, called the injector, is used to inject steam into the reservoir formation. This steam travels through the formation, heating the oil and creating a steam chamber. The second well, known as the producer, is placed below the injector and is used to collect the heated oil as it drains downwards due to gravity.
This technique effectively utilizes gravity as the primary force for oil movement, making it an efficient method for recovering heavy oil or bitumen. SAGD is particularly suitable for reservoir formations with high oil viscosity, depth, and thickness.
The implementation of SAGD requires careful reservoir characterization and engineering design to ensure optimal steam distribution. Additionally, it is important to maintain accurate steam-injection rates, pressure differentials, and temperature control to avoid unwanted effects such as steam breakthrough, excessive water production, or steam channeling.
SAGD has proven to be a successful method for heavy oil recovery in many oil sands projects globally. It provides a sustainable way to extract oil resources that would otherwise be difficult to recover using conventional oil recovery methods.
