How is the oil released from the rock?
In order to release the oil from the kerogen, the rock must be heated to about 650 to 700 degrees Fahrenheit in an oxygen-free environment. This process is called “retorting.” Two different methods have been used in the past to recover oil from the oil shale rock: surface retorting and in situ retorting. On average, approximately three quarters, or less, of the oil contained within the kerogen may be released using these techniques, depending on the physical properties of the rock itself (porosity, permeability, cementation, etc.).Surface retorting usually involves recovering the oil shale by using standard surface mining or underground mining techniques and then feeding the rock into a kiln for heating. After the oil has been removed from the rock, the spent shale is returned to the mined-out portions of the surface pit or under-ground mine workings, or maintained in a permanent surface spoil dump.In situ retorting is normally done at depth, leaving the oil shale beds in the ground. T
