Sedimentary rocks containing anomalous values of organic matter are found in certain intervals of the sedimentary sequence in Israel and adjacent countries. However, only Upper Cretaceous sequence (Mount Scopus Group) deposited during the Santonian to Paleocene, and especially the Mishash and the Ghareb formations are considered in Israel to have possible economic potential. The Oil Shale Member of the Ghareb Formation reaches a maximum sub-surface thickness of ~130 m in the northern Negev.
Based on Hutton's nomenclature, Israeli Oil Shale can be termed Marinite. Bituminous sequences, which now occur in synclinal structures, represent increase in tectonic activity, deepening of basins and probably relatively high productivity levels. Suitable conditions (i.e., fast burial, depletion of oxygen in the water bodies) enabled the preservation of Oil Shale in many basins. It is plausible that their original distribution was wider than today but decreased due to oxidation and epigenesis.
In most rocks termed Oil Shale in Israel, the main inorganic constituent is carbonate (chalk and marl). The “rich” samples contain 65 to 80% carbonates and 2-15 % clays. The density of the domestic Oil Shale is between 1.6-2.1 gr/cm3, a value that decreases with an increase in the content of organic matter. Several studies have suggested that the organic-matter enriched sequence of the Mount Scopus Group is the source rock for hydrocarbon showings (oil, asphalt, gas) found in the Dead Sea Rift and its margins.
The rock is generally dense and of low permeability, so that the flow of a significant amount of fluid and gas is apparently possible only through cracks, or when promoted by heating. Parts of the Oil Shale sequence are also characterized by high moisture content (non-combined water) of some 20%. These properties may pose difficulties for in-situ utilization techniques.
Reserves and grades
There are indications that some 15% of the country is underlain by Oil Shale beds. The theoretical, geological Oil Shale reserves in Israel are enormous, and may reach a figure well above hundred billion tons. However, mineable reserves form only a tiny fraction of that figure and are probably applicable to deposits associated with active phosphate mining areas. Advance in the development of in-situ techniques may probably enlarge the mineable reserves figure of the Israeli Oil Shale.
They vary in thickness from 30 to 450 meters in more than 30 occurrences throughout the country. For most of these, overburden to the top of the Oil Shale is 50-250 m, and in a few fields (e.g., Nabi-Musa, En-Boqeq, Oron) parts of the sequence are exposed.
The organic matter content of Israeli Oil Shale is 10-25% EOM (easily oxidized material) or approximately 6-15% TOC. This is roughly equivalent to 40-100 shale-oil litres per metric ton, and around 800-1,800 KCal/Kg in calorific value units. These oil yield figures are equal to 12-27 U.S. gallon/ton; a rough, average figure of 20 gallon/ton may be used to characterize the Israeli Oil Shale. Thus, in terms of quality, the Israeli Oil Shale may be considered as of poor to medium grade.
In previous domestic surveys, a cut-off value of 10% EOM was used to calculate quantities and grades. In the Mishor Rotem deposit, prospecting activity began in the 1970's and has continued irregularly together with associated research into energy production.
Since the Oil Shale occurrences in Israel and Jordan have many similarities, bi-lateral cooperation may have an advantage.
The Oil Shale Fired Power Plant in Mishor Rotem
The first tests (1978-81) were carried out in a 0.1 MW pilot plant, and between 1982 and 1986, the PAMA company established and operated a 1 MW fluidized-bed pilot plant. An advanced R&D program was funded by PAMA and the Israel Ministry of National Infrastructures with an investment of some $30 million, and the ~13 MW demonstration plant was completed in 1989. It has been successfully operated since 1990. The generated energy is sold to the Israeli Electric Corporation, and low-pressure steam is supplied to an adjacent industrial complex. Since 2000, the power station has been operated by the Rotem Amfert group.
The power station is fed by approximately 0.5 million tons of Oil Shale annually, mined at a nearby open-pit mine. A large part of the ash generated in the process is used in products such as cat litter. Most of the ash product is distributed in Europe under the commercial name Alganite.
The development of the Israeli Oil Shale industry raises some environmental concerns, mainly due to damage that may be caused by large scale open-pit mining and the possibility that hazardous materials could be generated during utilization processes. Several solutions may reduce these concerns, of which two are presently important:
(1) Combined exploitation of the closely associated Oil Shale and phosphates. This would reduce the volume of extracted material (both overburden and rejected beds) and the costs, thus facilitating the mining of deeper ores.
(2) Advanced in-situ utilization techniques. Such technologies may be applicable in deposits that are not mineable via open-pits and are close to urban and industrial areas.
Potential environmental hazards would more easily be monitored in what would be near-close-system processes.
Agenda of the Israeli Ministry of National Infrastructures
The Israel Ministry of National Infrastructres encourages projects involving the testing of new methods, including in-situ, underground techniques, for the utilization of Oil Shale as an energy source.
The government is currently considering incentives to interpreneurs in this respect, taking into account environmental issues.
Map of Oil Shale Desposits in Israel
Abridged from a poster presented in the 26th Oil Shale Symposium, Golden, Colorado