In Situ (meaning “in-place”) extraction of the bitumen occurs in areas where the bitumen reserves are too deep for mining. There are many types of in situ extraction; including thermal in situ processes, which inject steam into the deposit to heat the bitumen in order to pump it to the surface.
Most thermal in situ projects use groundwater. Groundwater is the water that is found under the ground surface in the spaces between rocks, soils and overburden.
Projects may use non-saline (fresh) or saline (brackish) groundwater depending on the availability of different water sources in the locale of the project.
Many thermal in situ projects use vast quantities of steam injected into the bitumen reservoir to “melt” the bitumen and then pump the water/ bitumen emulsion back to the surface where the water and bitumen can be separated. In most projects almost all of the “produced water” is cleaned and recycled back into the process.
Additional “make-up” water is required to account for loss of water in the process; these losses occur in various places such as the following:
- Some water is lost within the reservoir;
- Projects using brackish or saline water lose some of their water in the process to remove the dissolved solids.