You must log in to edit PetroWiki. Help with editing
Content of PetroWiki is intended for personal use only and to supplement, not replace, engineering judgment. SPE disclaims any and all liability for your use of such content. More information
Vapor extraction
Vapor extraction, also called Vapex, is the process of recovering heavy oil and bitumen from the reservoir utilizing vaporized solvents[1]. Vaporized solvents are injected mostly through horizontal wells. After injection, the solvent vapors dissolve into the high viscosity oil at the gas/oil interface and diffuse into the interior of the oil zone, which reduces the oil viscosity and promotes the gravity drainage of oil towards a production well, often located a short distance below the injection well.
Vapor injection
The ultimate objective of the process is to produce oil by reducing its viscosity in order to increase the gravity drainage rate. Vapor extraction is considered advantageous in some reservoirs, which are not amenable to thermal recovery methods. This advantage comes from the absence of issues like heat loss to overburden rock in thermal recovery methods. However, the oil production in this process is slow compared to thermal recovery, due to its reliance on mass transfer by solvent diffusion which is much slower than heat transfer by conduction and convection.
Advantages
- The process does not require expensive surface facilities such as water treatment facility and steam generators needed in steam injection processes.
- The Vapex process has lower greenhouse gas emission (80% lower than steam injection processes) and offers the additional scope for carbon dioxide sequestration when CO2 is used as a component in the injected solvent. Hence this process is environmentally friendly.
- The Vapex process is technically applicable to a wider range of heavy oil and bitumen reservoirs. It can be applied to reservoirs that carry high amounts of water in pores, thin pay zones, low thermal conductivities of the formations, and reservoirs with bottom water layers.