Oil-shale extraction technology has a new owner

As a long-term petroleum source, oil-shale reserves are vast but remain elusive. Oil-services giant Schlumberger is aiming to change that with the recent purchase of a radio-frequency (RF)/critical-fluid (CF) extraction technology that unlocks this vast resource and brings it to the surface in a cost-effective and environmentally sound manner.

Oil shale is a type of sedimentary rock that contains solid bituminous material, known as kerogen, that releases oil or gas when heated. While oil-shale deposits are found in many places around the world, the largest deposits by far reside in the Rocky Mountain region of the U.S. Oil-shale reserves are estimated at nearly 2 trillion bbl in the states of Colorado, Utah and Wyoming alone, according to the U.S. Department of Energy. This quantity would be sufficient to meet U.S. demand at current levels for the next 250 years.

However, successfully harvesting this vast resource has been technically, economically, and environmentally challenging. The most common methods of recovering oil shale include a mining step, in which the shale is mined from the surface or underground and then transported to a facility for further processing. The waxy, solid nature of the shale necessitates a heating process, known as retorting, to release the trapped oil and allow it to flow out of the rock matrix.

The large environmental and processing costs associated with this method of oil-shale extraction have prevented it from becoming a major petroleum source. According to an Environmental Impact Statement (EIS) prepared by the U.S. Department of the Interior's Bureau of Land Management, the environmental impacts include emission of greenhouse gases during mining and processing, disturbance of mined lands, need for disposal of the spent shale, use of water resources, and impacts on air and water quality. These factors contribute to the relatively high cost of producing oil from shale, which the EIS estimates at greater than USD60/bbl.

The RF/CF extraction technology developed by Raytheon and technology partner CF Technologies aims to lower these environmental and processing impacts dramatically by employing an in-situ retorting process. In this process, wells are drilled into the shale strata using standard drilling equipment. Raytheon's RF transmitters (which have been used extensively for radar and guidance systems) are then lowered into the well. The transmitters emit a radio signal at a frequency that uniformly heats the shale and liquefies the trapped petroleum.

Supercritical carbon dioxide is then pumped into the heated shale formation to extract the oil from the rock and carry it to a producing well. At the surface, the carbon dioxide is separated from the oil, reprocessed, and pumped back into the injection wells. The recovered oil is sent for further processing and refining.

Raytheon estimates that this combination of RF technology to heat the shale followed by a critical-fluid flush to bring the oil to the surface will result in significant environmental benefits and cost savings over other shale-extraction methods. The technology can retrieve 4 to 5 bbl of oil for every barrel consumed during the extraction process, while other in-situ retorting processes reportedly extract only 1.5 to 3 bbl for every barrel consumed.

In addition, the RF/CF technology enables extraction to start 1 to 2 months after the transmitters are activated. Other in-situ methods using in-ground electrical heating systems may take 2 to 3 years to heat the shale sufficiently for oil to flow.

The sale to Schlumberger promises to open up new application areas for this technology and is part of a Raytheon initiative to expand its RF and communication-systems technologies to a customer base outside of the security and defense arenas. Four years ago, Raytheon created the Mission Innovation group within its Integrated Defense Systems (IDS) division, which had a goal of focusing mature defense capabilities to address challenges in energy exploration and the environment.

"Schlumberger is the world leader in bringing new technology to the field for the exploration and production of oil," said Lee Silvestre, vice president of the Mission Innovation group of Raytheon IDS. "Its acquisition of this technology is an important milestone in Raytheon's approach to applying proven technology that can unlock potential in adjacent markets."

To learn more about this oil-extraction technology, contact Raytheon.

Ted Moon is the Technology Editor of JPT Online. He brings information on emerging technologies, R&D successes, new field applications, updates from SPE papers about recent innovations, and more. If you have a question or suggestion for future article topics, email Ted at teched@spe.org This e-mail address is being protected from spam bots, you need JavaScript enabled to view it .