The letters following each Review Question refer to the corresponding Learning Objective from the Chapter Opener. What are tar sand and oil shale, and how can oil be extracted from them? (D)

Tar sand (also known as oil sand or bituminous sand) is a combination of sand, clay, water, and a dense form of petroleum called bitumen. These deposits are usually found in large quantities and are considered unconventional oil resources. Oil shale is a sedimentary rock that contains a solid organic material called kerogen. When heated, kerogen can be converted into a liquid or gaseous hydrocarbon, which can then be processed into conventional oil.

The process of extracting oil from tar sands goes through two main steps. A. Surface mining: For tar sands deposits found near the Earth's surface, open-pit mining techniques are used. The process involves removing vegetation and overburden (layers of soil and rock on top of the deposit) to expose the tar sands, which are then excavated and transported to extraction facilities. B. Bitumen Separation: At the extraction facility, the tar sands are mixed with hot water and chemicals to create a slurry. The slurry is then processed in separation cells, where the bitumen floats to the top, water containing sand and clay sinks, and the residual solids can be removed. The collected bitumen is then further processed and upgraded into synthetic crude oil.

Oil extraction from oil shale primarily involves two methods: A. In-situ (in place) Processing: In this process, the oil shale remains in the ground during the extraction process. Heaters are placed inside boreholes to heat up the rock and convert the kerogen into a liquid or gas. These liquids or gases are then collected and processed into conventional oil. B. Surface (ex-situ) Processing: Oil shale is mined using open-pit or underground mining methods and brought to the surface. After mining, the oil shale is heated in a process called retorting, which converts kerogen into a liquid or gas and collects it for further processing into conventional oil. The remaining solid waste, called spent shale, is then disposed of.