The LLNL RISE process was an experimental shale oil extraction technology developed by the Lawrence Livermore National Laboratory

Lawrence Livermore National Laboratory

The Lawrence Livermore National Laboratory , just outside Livermore, California, is a Federally Funded Research and Development Center founded by the University of California in 1952...

. The name comes from the abbreviation of the Lawrence Livermore National Laboratory and words 'rubble in situ extraction'.

LLNL RISE is a modified in situ extraction technology originally proposed by Rio Blanco Oil Shale Co. and developed by the Lawrence Livermore National Laboratory. It is classified as an internal combustion technology. The process was described in 1975 by Lewis A. E. and A. J. Rothman.

In the LLNL RISE process a part of the oil shale

Oil shale

Oil shale, an organic-rich fine-grained sedimentary rock, contains significant amounts of kerogen from which liquid hydrocarbons called shale oil can be produced...

 deposit (roughly 20% of the total deposit) is removed by the conventional mining technique. The remaining deposit the is broken with explosives to increase porosity

Porosity

Porosity or void fraction is a measure of the void spaces in a material, and is a fraction of the volume of voids over the total volume, between 0–1, or as a percentage between 0–100%...

 of the deposit. As a result, a large underground retort chamber by 20 to 100 m (65.6 to 328.1 ) square and 100 to 300 m (328.1 to 984.3 ) high is created. The retort chamber is ignited at the top. The combustion zone moves downward as an oxygen

Oxygen

Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

 gas provided, similar to the process developed by the Occidental Petroleum. The heat causes retorting process converting kerogen

Kerogen

Kerogen is a mixture of organic chemical compounds that make up a portion of the organic matter in sedimentary rocks. It is insoluble in normal organic solvents because of the huge molecular weight of its component compounds. The soluble portion is known as bitumen. When heated to the right...

 in oil shale to oil shale gas

Oil shale gas

Oil shale gas is a synthetic gas mixture produced by oil shale pyrolysis. Although often referred to as shale gas, it differs from the natural gas produced from shale, which is also known as shale gas.-Process:...

 and shale oil

Shale oil

Shale oil, known also as kerogen oil or oil-shale oil, is an unconventional oil produced from oil shale by pyrolysis, hydrogenation, or thermal dissolution. These processes convert the organic matter within the rock into synthetic oil and gas...

vapors. Some oil is collected at the bottom of the retort, other collected at the surface as vapors.

The process was never used commercially. It was tested by using experimental simulated retort with capacity of 6 tonnes of oil shale per day.