This section provides an overview for butanes:
In Alberta, butanes (C4) are recovered from the raw natural gas stream. Most of the natural gas liquids (NGLs) supply is recovered from the processing of natural gas at gas plants. Other sources include crude oil refineries, where small volumes of butanes are recovered, and gases produced as by-products of bitumen upgrading, called off-gas. Off-gas is a mixture of hydrogen and light gases, including ethane, propane, and butanes. Most of the off-gas produced from oil sands upgraders is currently being used as fuel for oil sands operations.
Butanes and other NGLs are recovered mainly from the processing of natural gas. Field gas processing facilities ensure that natural gas meets the quality specifications of natural gas pipeline systems, which may require removing NGLs to meet pipeline hydrocarbon dew point specifications. Field plants generally recover additional volumes of NGLs—more than what is required to meet pipeline specifications, depending on the plant’s extraction capability—that are sold separately to obtain full value for the NGL components. Generally, the heavier NGLs (butanes and pentanes plus) are removed at field plants. Field plants send recovered NGL mix to centralized, large-scale fractionation plants where the mix is fractionated into specification products.
Gas reprocessing plants, often referred to as straddle plants, recover NGL components or NGL mix from marketable gas. They are usually located on main gas transmission pipelines at border delivery points.
Butanes are used as a feedstock to refineries to blend with heavy oil and nonupgraded bitumen and to petrochemical facilities to create value-added products such as an octane additive for gasoline and methanol. Butanes can also be used as a solvent with steam-assisted gravity drainage for enhanced in situ bitumen recovery.