Oil Shale

Mr. Campbell and Dr. Conca provided one of the 10 summaries for energy resource commodities on uranium, thorium, and rare earths (pp. 450-458). Other experts provided sections on geothermal, coal and unconventional energy resources, and on an analysis of energy economics and technology, all prepared by
committees of the Energy Minerals Division of the American Association of Petroleum Geologists. Unconventional energy resources, as used in this report, are those energy resources
that do not occur in discrete oil or gas reservoirs held in structural or stratigraphic traps in sedimentary basins. Such resources include coal-bed methane, oil shale, uranium and thorium
deposits and associated rare-earth elements of industrial interest, geothermal, gas shale and liquids, tight gas sands, gas hydrates, and bitumen and heavy oil. Current U.S. and global
research and development activities are summarized for each unconventional energy resource commodity in the topical sections of this report, followed by analysis of unconventional
energy economics and technology.

Summary:
This chapter presents a descriptive and illustrative account of phase behavior in the seven naturally occurring petroleum fluids and ties all the known eleven phase-transition concepts in a unified narrative. The figures and tables contained in this report are designed so that they could effectively support the discussion about molecular make-up of petroleum fluids, P- and T-effects on phase behavior and phase transition points.
      Seven naturally occurring hydrocarbon fluids are known as petroleum fluids. They include, in the order of their fluidity, natural gas, gas condensate (or NGL), light crude, intermediate crude, heavy oil, tar sand and oil shale.  In this report we present a generalized description of the various phase transitions, which may occur in petroleum fluids with emphasis on heavy organics deposition. 
      At first the nature of every petroleum fluid is presented.  Their constituents including their so-called impurities are identified and categorized. Heavy fractions in petroleum fluids are discussed and their main families of constituents are presented including petroleum wax, diamondoids, asphaltenes and petroleum resins.  Then the generalized petroleum fluids phase behavior is discussed in light of the known theory of phase transitions. The effects of variations of composition, temperature and pressure on the phase behavior of petroleum fluids are introduced.  Finally eleven distinct phase-transition points of petroleum fluids are presented and their relation with state variables and constituents of petroleum fluids are identified.  This report is to generalize and relate phase behaviors of all the seven naturally occurring petroleum fluids into a unified perspective.  This work is the basis to develop a comprehensive computational model for phase behavior prediction of all the petroleum fluids, which is of major interest in the petroleum industry

The primary function of natural gas well cementing is to provide downhole zonal isolation. However , the residual non-aqueous drilling fluid in cement and on the surface of the casing can weaken the bond of hardened cement to the casing. In this paper, the amount of remaining drilling fluid both in cement and on the casing is quantified by the fluorescent dye method, which is verified by other two methods, mass difference and laser scanning. The essential factor-surface roughness that can significantly affect the amount of residual drilling fluid-is investigated. Results show good correlations between the thickness of the remaining drilling fluid and the surface roughness. The comparison of mud removal efficiency of two commercial spacers indicates that microemulsion can remove more drilling fluid than the common spacer, as pointed out in the literature; however, microemulsion is also apt to remain on the casing and thus reduce the bonding between cement and the casing.

The Eocene Green River Formation and associated fluvial strata host a large variety of widely distributed and laterally extensive synsedimentary to early post-depositional deformation features. Although mostly overlooked in past studies, these structures provide insight into the rheology of the sediments and hydrodynamic conditions at the time of deformation. They also have implications about basin configuration and bottom topography, as well as the structural history of the region.
In the Uinta and Piceance Creek Basins of Utah and Colorado, deformed intervals are present in littoral (sand-dominated) to profundal (oil shale) lacustrine deposits, as well as fluvial facies. Deformation structures exhibit a wide range of morphology, size, and style, ranging from ductile (convolution, folding, load and pinch-and-swell structures) to brittle (microfaults, breccias), to sedimentary injection into fissures and cracks forming dikes, to various mass transport deposits. In most cases, these layers are bound above and below by undisturbed beds of similar facies with horizontal bedding planes, which implies short-lived but recurring events that affected only sediments with a susceptible rheological state. Deformation typically occurred intrastratally, i.e. under shallow burial. The variations in deformation style, size, morphology, and areal extent are related to differences in grain size and type, water content, cementation, organic content, thickness of susceptible material, lateral facies variation, and the nature of the driving force. Some of the sedimentary injection features overprint each other, indicating multiple events affecting a single interval.
We interpret most of these features as seismically induced (‘seismites’) based on: (1) the tectonic setting of the basin; (2) the sedimentary environment and sedimentological characteristics of the host succession; (3) the lateral extent of deformation structures; (4) their recurrence at different stratigraphic levels; and (5) their similarity to those ascribed to seismically induced deformation elsewhere and reproduced experimentally. They developed as a result of increased pore pressure and a complex combination of extensional, compressive, and shear stresses acting in many directions caused by shaking during strong earthquakes. Mass transport deposits indicate in situ disruption and failure of the imperceptibly dipping lake floor. These ‘seismites’ represent the direct sedimentary record of syndepositional tectonic activity in the Uinta Basin.

We present a coherent and unified group of general explanations for the various phase transitions, which may occur in the seven naturally occurring petroleum fluids with emphasis on their heavy organics. The seven petroleum fluids include, in the order of their fluidity, natural gas, near-critical gas-condensate, light crude, intermediate crude, heavy oil, tar sand and oil shale.

At first the nature of every petroleum fluid is presented including their constituents and their heavy fractions. Then their main families of constituents are presented.

The generalised petroleum fluid phase behaviour is introduced in light of the well-known theory of phase transitions. The effects of variations of composition, temperature and pressure on petroleum fluids phase behaviour are introduced. Their 11 distinct phase-transition points are presented and their relation with state variables and constituents are identified. This report is the basis for development of a unified phase behaviour prediction model of all the petroleum fluids.

The high cost of importing heavy fuel oil from neighbouring countries of Jordan stimulated the need to
consider renewable energy as an alternative to imported power. The paper describes a systematic experimental
study on the pilot solar updraft tower power plant model system. Particular attention is given to
measurements of air velocity, temperature, solar radiation and voltage difference. This is the first pilot solar
updraft power plant that has been built in Jordan to evaluate such technology in Mutah Area. In this paper,
all the experimental data were taken from a very small pilot project (compared with other prototypes that we
constructed which were placed in the backyard of our faculty). For the experimental part, the solar updraft
power plant was a pilot project with an updraft power plant height H = 4(m), updraft power plant radius
Rc = 0.29(m), plastic solar collector area Acoll = 36(m2), collector roof height = 1(m), wind turbine that
was a compensation of the suction fan with a diameter Dfan = 0.5(m), and a small generator (6V) The
experimental results in this paper show that the maximum height (Hmax) gradually increases with the solar
irradiation (G). Also, in the same way, with the pressure difference (p) increases with solar irradiation

This report, provides an analysis of infrastructure, economic, geological, environmental and law-related aspects of development of the unconventional gas sector both in Poland and in the EU. It also gives recommendations regarding this new challenge for the EU’s energy policy.

La evaluación final se realizó por medio de la interpretación estratigráfica y estructural de los PayShales arrojando como resultado la zona 4 al NW del área de estudio como la mejor para profundizar la evaluación de un yacimiento del tipo no convencional.

Laterally extensive intervals containing sedimentary deformation features are identified in outcrops of lacustrine deposits of the Eocene (∼ 52–51 Ma) Green River Formation in Fossil Basin, southwestern Wyoming. Fossil Basin is the smallest of the paleo-lakes in the Green River system and is located in the Sevier Fold and Thrust Belt, which was tectonically active during deposition. Deformation structures include convolute lamination, load structures, hybrid brittle–ductile features, sedimentary dikes, microfaults, fluid-escape features such as cusps and pipes, oil-shale breccias, and mass-transport deposits. In most cases these structures are hosted by finely laminated, variably organic-rich carbonate mudstones that accumulated in a low-energy profundal lacustrine environment. Deformed intervals range from a few centimeters to 5 m in thickness and are bound above and below by undeformed strata of the same facies, which demonstrates the early post-depositional timing of deformation. The distribution of these features indicates a primary control exerted by sediment rheology, resulting from variation in grain size, clay and organic content, and degree of lithification, which in turn were governed by the depositional environment and early diagenesis.

Based on their morphological attributes, lateral extent, and recurrence at different stratigraphic levels, along with their sedimentary environment and the tectonic setting of the basin, the deformation structures are interpreted to be “seismites,” i.e., the result of stresses induced by syndepositional earthquakes, and other potential trigger agents are rejected. Moreover, stratigraphic relationships indicate that these small-scale deformation features as well as the mass-transport deposits, formed on a virtually flat lake floor, ruling out instability caused by the gravitational regime. Syndepositional deformation in Fossil Basin points to tectonic activity along the nearby Absaroka and/or Hogsback thrusts and related fault systems. Seismites point to possible tectonic forcing as a mechanism for changes in bathymetry and sedimentation in the Green River Formation and, consequently, demonstrate their potential for elucidating the tectonic history of other lacustrine and marine basins.

A B S T R A C T Recent advances in fracture-timing techniques have led to new insights about sequences and mechanisms of fracture formation in mudrocks. Methods to constrain fracture timing in mudrocks include: (i) field evidence, including crosscutting relationships and evidence of compaction; (ii) petrographic evidence, including signs of soft-sediment deformation and diagnostic mineral assemblages or textures; (iii) stable-isotopic evidence; (iv) thermometric dating using burial history modelling; and (v) radiometric age-dating. In this contribution, we briefly review each method with salient examples from the literature. Many documented examples of mudrock-hosted fractures formed during early burial, a non-intuitive finding that demands a re-assessment of our assumptions about what types of materials can develop opening-mode fractures. In general, the style and distribution of fractures varies dramatically based on fracture timing, highlighting the importance of constraining timing for predicting fracture patterns and interpreting their mechanisms, including the role of fluid flow.

Underground oil shale mining has been applied for ninety years in Estonian deposit in the middle-north part of Baltic oil shale deposit. The underground mining method of oil shale creates underground free space and the mine workings are filled with water after closure, which makes issues of land stability topical.

In 2012 and 2013 extensive sedimentological field work was conducted to study the depositional setting, the regional geology and facies relationships, and measure sections of the Green River Formation in all the subbasins, in Wyoming, Colorado and Utah (USA). Several pervasive horizons of seismically induced deformation structures were identified mainly in profundal lacustrine sediments. Deformation is represented by brittle and plastic behaviour, as well as sediment injection and mass transport. The deformed layers are confined by undeformed beds which implies sporadic short-lived events that affected only near-surface sediments with susceptible rheological state at the time.
Based on: (1) the tectonic setting of the lacustrine basins; (2) the sedimentary environment and sedimentological characteristics of the successions in which the deformed layers occur; (3) their lateral extent and proximity to known active fault systems during the time of the deposition of host sediments; (4) their recurrence at different stratigraphic levels, intervals showing large-scale sedimentary deformation structures are interpreted as result of in-situ loss of shear strength, formed by increased pore pressure and vertical or horizontal stress induced by seismic activity

The modeling of conjugate development of fractures and fluid flow remains a significant subject in a diversity of rock engineering. Continuum numerical methods are paramount in the modeling of rock engineering practice problems, merely with restrained capacities in modeling the problem of fracture development coupled by fluid flow. There exists a demand for them to be understood in details. Driven by this, we demonstrated an approach based on a three-dimensional development of fracture of an abstract model condensed to two-dimensional analysis comprising rocks with fractures. In the framework of a continuum method of modeling, the contact between the fracture development and deformation was paired with fluid flow. A 3-D model was established in this case for a shale reservoir and fluid was injected at multiple pressures to understand the initiation and propagation of fractures, as applied to the field of hydraulic fracturing. The stress, strain, displacement in the reservoir were monitored at multiple injection pressures. Linear relations of injection pressures were observed with these parameters. A detailed insight with quantification of the values is given into the subject based on the findings of this study.

FOR CITATIONS: Yohannes Yihdego, Hilmi S. Salem, Bediaku G. Kafui, and Zarko Veljkovic (2018): Economic geology value of oil shale deposits: Ethiopia (Tigray) and Jordan, Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 40(17): 2079-2096 Taylor & Francis. Published Online: 9 July 2018.
DOI: https://doi.org/10.1080/15567036.2018.1488015
URL: https://www.researchgate.net/publication/326274780_Economic_geology_value_of_oil_shale_deposits_Ethiopia_Tigray_and_Jordan

ABSTRACT: Oil shale is an organic-rich, fine-grained sedimentary rock, containing kerogen, from which liquid hydrocarbons (called shale oil) can be produced. The oil shale deposits in the Tigray region are found in the northern parts of Ethiopia, Eastern Africa. They are of Upper Paleozoic in age, existing as remnants of the Cretaceous erosion period, underlain by tillites and overlain by sandstones. They were formed during the glacial retreat followed by marine deposition of shales in a basin created by the enormous load of the glaciers. The Ethiopian-Tigray oil shale deposits cover an area extending over approximately 30 km 2 , with an average mineable bed-thickness of 55 m, showing on the upper part inter-beds and laminations of shaley limestones. The oil shale resources in this region are estimated to be approximately 4 billion tonnes. https://www.tandfonline.com/doi/full/10.1080/15567036.2018.1488015

Outcrops and cores from the top of the lacustrine Tipton Member and the base of the Wilkins Peak Member (~51.5 Ma) of the Eocene Green River Formation, Bridger Basin in southwestern Wyoming yield a wide variety of sedimentary deformation features many of which are laterally extensive for more than 50 km. They include various types of folds, load structures, pinch-and-swell structures, microfaults, breccias and sedimentary dikes. In most cases deformation is represented by hybrid brittle–ductile structures exhibiting lateral variation in deformation style. These occur in low-energy, profundal organic-rich carbonate mudstones (oil shales), trona beds, tuffs, and profundal to sublittoral silty carbonate deposited in paleolake Gosiute. The deformation is not specific to the depositional environment because sedimentary units stratigraphically higher with similar facies show no deformation.
The studied interval lacks any evidence for possible trigger mechanisms intrinsic to the depositional environment , such as strong wave action, rapid sediment loading, evaporite dissolution and collapse, or desiccation, so 'endogenic' causes are ruled out. Thus, the deformation features are interpreted as seismites, and change in deformation style and inferred increase in intensity towards the south suggest that the earthquakes were sourced from the nearby Uinta Fault System. The 22 levels exhibiting seismites recognized in cores indicate earthquakes with minimum magnitudes between 6 and 7, minimum epicentral intensity (MCS) of ~9, and varying recurrence intervals in the seismic history of the Uinta Fault System, with a mean apparent recurrence period of ~8.1 k.y. using average sedimentation rates and dated tuffs; in detail, however, there are two noticeably active periods followed by relative quiescence. The stratigraphic position of these deformed intervals also marks the transition between two distinct stages in lake evolution, from the balanced-filled Tipton Member to the overlying, underfilled Wilkins Peak Member. Thus, these seismites are evidence for regional-scale changes in lacustrine sedimentation of Eocene Lake Gosiute in response to syndepositional tectonic activity. Analysis of synsedimentary deformation features is, therefore, a promising yet under-utilized tool to trace the tectonic evolution of lacustrine deposits of the Green River Formation and other tectonically active marine and non-marine basins.

A batch adsorption system using cotton stalk as a bioadsorbent was investigated to remove methylene blue from aqueous solution. The system variables studied include adsorbent particle size, initial dye concentration and adsorbent dose. Based on the isotherm data obtained from the fittings of the adsorption kinetics, the Freundlich model (Regression coefficient R ≈ 0.99) appears to fit the adsorption better than the Langmuir model (Regression coefficient R ≈ 0.89). The Freundlich and Langmuir monolayer capacity had a mean values of 1.29 l/g and 1.054 mg/g, respectively.

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China is appraised to have the world's largest exploitable reserves of shale gas, although several legal, regulatory, environmental and investment-related issues will likely restrain its scope. China's capacity to successfully face these hurdles and produce commercial shale gas will have a crucial impact on the regional gas market and on China’s energy mix, as Beijing strives to decrease reliance on imported oil and coal, while attempting to meet growing energy demand and maintain a certain level of resource autonomy. The development of the unconventional natural gas extractive industry will also endow China with further negotiating power to obtain more advantageous prices from Russia and future liquefied natural gas (LNG) suppliers. This paper, adopting a comparative perspective, underlines the trends learned from unconventional fuel development in the United States, emphasizing their potential application to the Chinese context in light of recently signed production-sharing contracts between qualified foreign investors and China. The wide range of regulatory and enforcement problems in this matter are accrued by an extremely limited  liberalization of gas prices, lack of technological development, and political hurdles curbing the opening of resource extraction to private investors. These issues are exacerbated by concerns related to the risk of water pollution deriving from mismanaged drilling and fracturing, absence of adequate regulation framework and industry standards, entailing consequences on social stability and environmental degradation.

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Seismogenic sedimentary structures—seismites—provide an opportunity to understand the effects of syndepositional tectonics on lacustrine sedimentation. The lowermost Wilkins Peak Member (Eocene Green River Formation, Wyoming, USA) contains laterally extensive intervals displaying folds, load structures, mixed brittle–ductile deformation, microfaults, breccias and sedimentary dykes, which formed intrastratally in a low-energy, sublittoral lacustrine environment. They developed in situ by liquefaction and plastic or brittle behaviour of semi-lithified sediment, or by remobilization and injection of granular material. Their morphological attributes and lateral extent, zonation in deformation intensity, and the depositional setting all imply deformation triggered by earthquake-induced stresses in shallow-buried sediment. Their stratigraphic distribution coincides with a shift in hydrological conditions from a balanced-filled to an underfilled lake type, independent of climate change. This study is the first to ascribe seismites to a pulse of tectonic activity that caused a synchronous change in lacustrine evolution.

A modified first order kinetic equation with variable activation energy is employed to model the total weight loss of Ellajjun oil shale samples. Fixed bed retort with 400 g of oil shale sample size is used in this study in 350-550°C temperature range. Variable heating rate, h, in the range 2.6-5°C min À1 are tested.

The carbonate-rich sediments of the Eocene Green River Formation (53–43 Ma) were deposited in a complex lake system in present-day Wyoming, Colorado and Utah during the Laramide orogeny. Although syndepositional tectonic activity has been inferred previously for this interval, sedimentary deformation features linked to ancient earthquakes have never previously been studied.
Stratigraphic intervals with synsedimentary deformation features were studied at several locations in all the sub-basins to provide information on the paleotectonic history of the area. Laterally extensive deformed horizons are common in laminated deposits of Fossil Basin (WY), and include folds, water-escape structures, dikes, microfaults, and chaotically brecciated intervals that preserved flow structures. These indicate hydrofracturing, dewatering and the liquified state of sediments during deformation. Sediments deposited in sublittoral environments of the Bridger Basin (WY), at the boundary between the Tipton Shale and Wilkins Peak members, also show evidence of synsedimentary deformation. These features, some traceable laterally for tens of kilometers, imply tectonically influenced changes in sedimentary processes during that time. Pervasive deformation features are also present in the Mahogany Oil Shale Zone in the Piceance Creek and Uinta basins (CO, UT). Behavior ranges from brittle (fragmented laminites and faulted beds) to plastic (convolution, folds), to cm- to m-scale cracks filled with injected sediment. Deformation styles were controlled by the rheological properties of the host sediment.
All these structures resulted from increased pore pressures from cyclic loading, and vertical and horizontal stresses induced by ground motion. Typically, undeformed strata separate the deformed horizons, which indicates that brief (tectonically-driven) events affected only near-surface sediments that were rheologically susceptible to syndepositional deformation.

A rapid and practical test for oil-shale richness is of considerable technical importance. Although the Fischer-Schrader method has gained universal acceptance for determination of shale richness, there is need to relate results from this determination to fundamental parameters of the shale. One much-used relation is with elemental analysis, and numerous equations have been derived to correlate shale richness with organic carbon content. These relations have been reviewed, and from a number of intensively analysed samples selected from a coring in the Parachute Creek member of the Green River Formation equations relating oil yield by Fischer-Schrader determination to organic carbon content have been developed†
(wt %) oil = 0.8317(%Corg) - 0.2509
and
(gal/ton) oil = 2.216(%Corg) - 0.7714
Additionally, more detailed knowledge of the uniformity of organic material throughout the Green River Formation was obtained. It was found that the fraction of kerogen which on pyrolysis yields liquid products is constant stratigraphically throughout the formation, even though the oil composition is not.

Estonia has two of the world's largest oil shale firing circulating fluidized bed (CFB) units with a designed electrical capacity of 215 MW each. The units are based on double boiler CFB technology provided by Foster Wheeler Energia OY. The units are located at Eesti and Balti power plants (EPP and BPP). The paper presents analyses of data obtained from tests of oil shale and biomass co-combustion in the full-scale CFB boiler located at BPP. The tests were conducted at nominal boiler load: 100% (314 t/h), with a biomass thermal input of 15%. During the experiments ash samples from the furnace chamber (bottom ash), INTREX, super-/reheater (SH, RH), economizer (ECO), and air preheater (APH), and from all four fields of the electrostatic precipitator (ESP) were taken. Samples of fly ash for determining the mass division (total suspended particulates PM10 and PM2.5) were taken after the ESP. The gas analysis was performed at the ESP inlet. Analysis of the chemical composition of ash was carried out. The specific consumption of oil shale per useful heat and gross electricity were found and other techno-economic characteristics determined.

Oil shale utilisation losses reach 70% in some cases. These are closely related to legislation, backfilling and waste rock usage. Much smaller sections include production of oil, electricity and chemicals in which most of the research and development is performed today. Current urgent topics for investigating, testing and developing of oil shale mining related questions are backfilling, mechanical extracting of shale, fine separation, selective separation and optimised drilling and blasting. Reducing oil shale losses will be more actual in the future, because the depth of mining increases and the taxes for resource and pollutants are increasing as well.

Thermogravimetric (TG) data of oil shale obtained at MI (Waste to Energy laboratory) were studied to evaluate the kinetic parameters for El-Lujjun oil shale samples. Different heating rates were employed simulating pyrolysis reaction using Nitrogen as purging gas up to $800°C. The extent of char combustion was found out by relating TG data for pyrolysis and combustion with the ultimate analysis. Due to distinct behavior of oil shale during pyrolysis, TG curves were divided into three separate events: moisture release; devolatization; and evolution of fixed carbon/char, where for each event, kinetic parameters, based on Arrhenius theory, were calculated. Three methods were used and compared: integral method; direct Arrhenius plot method; and temperature integral approximation method. Results showed that integral method is closer to the experiment, while no relationship was observed between activation energy and the heating rate.

This paper describes vertical fine-scale geochemical heterogeneity of Estonian graptolite argillite (GA). GA samples from Pakri and Saka outcrop sections were collected at 20 cm intervals for chemical analysis of major and trace elements, including rare earth elements. The study indicates GA enrichment in U, V, Mo and Pb with respect to the average black shales and thus confirms the formerly reported data on GA geochemistry in general. However, the content of enriched elements and other trace metals was recorded to vary greatly across the sequences suggesting that trace metal distribution in GA is notably more heterogeneous than previously assumed. The origin of the observed complex distribution of trace elements was likely controlled by the interplay of different primary metal supply-sequestration factors/processes, such as synsedimentary redox-driven sequestration of redox sensitive elements, the provenance of clastic input, the postsedimentary redistribution, etc. 1.8 m, respectively. The weight of samples was approximately 2 kg. The samples were cleaned, dried, crushed and homogenized for chemical analysis. The sample powders were analyzed for major and trace element composition, including rare earth elements, in order to determine the geochemical changes across the section and general rock composition. Geochemical analysis was performed using X-ray fluorescence (XRF) and ICP-MS analysis.

The regulation of the shale industry in the EU stopped making headlines after the European Commission released a temporary regulatory package in 2014. It is not that there have been no shale related developments in the EU and Member States. The time and public funds spent now by the Commission on scientific research interwoven with regulatory analyses might contribute to the reduction of industry costs as a result of not only better technology but also of a streamlined investment-process which would mitigate potential conflicts between developers, landowners, local communities, NGOs as well as central and local authorities.

The effect of mineral matter content on the activation energy of oil shale pyrolysis has been studied. Kerogen was isolated from raw oil shale by sequential HCl and HCl/HF digestion. Oil shale and kerogen samples were pyrolyzed in a Thermogravimetric Analyzer at different heating rates (1, 3, 5, 10, 30, and 50°C/min) up to a temperature of 1000°C. Total mass loss of all oil shale samples remained almost constant irrespective of the heating rate employed, whereas it decreased with the increase of heating rate for kerogen (74.5 to 71.4%). From the pyrolysis profile activation energy (Ea) was found to vary between 70 and 83 kJ/mol for oil shale, while 82-112 kJ/mol has been determined for isolated kerogen. An increase of both Ea and pre-exponential factor was observed with an increasing heating rate. It is concluded that the mineral matter in oil shale enhances catalytic cracking as is evident from the reduced Ea values of oil shale compared with those for kerogen.

Twenty-eight different tea samples sold in the United States were evaluated using high-performance liquid chromatography (HPLC) with fluorescence detection (FLD) for their contamination with polycyclic aromatic hydrocarbons (PAHs). Many PAHs exhibit carcinogenic, mutagenic, and teratogenic properties and have been related to several kinds of cancer in man and experimental animals. The presence of PAHs in environmental samples such as water, sediments, and particulate air has been extensively studied, but food samples have received little attention. Eighteen PAHs congeners were analyzed, with percentage recovery higher than 85%. Contamination expressed as the sum of the 18 analyzed PAHs was between 101 and 1337 mg/kg on dry mass and the average contents in all of the 28 examined samples was 300 mg/kg on dry mass. Seven of the congeners were found in all samples with wide ranges of concentrations as follows: fluorene (7-48 mg/kg), anthracene (1-31 mg/kg), pyrene (1-970 mg/kg), benzo(a)anthracene (1-18 mg/kg) chrysene (17-365 mg/kg), benzo(a)pyrene (1-29 mg/kg), and indeno(1,2,3-cd)pyrene (4-119 mg/kg). The two most toxic congeners benzo(a)pyrene and dibenzo(a,h)anthracene

The concentrations of minerals and trace elements in the Lokpanta oil shale from the Lower Benue Trough, Nigeria have been determined by X-ray diffraction (XRD) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), respectively. X-ray diffraction data were evaluated using the SIROQUANT™ interactive data processing system based on Rietveld interpretation methods. A new method of trace element determination in oil shale, involving LA-ICP-MS analysis of glass beads prepared by fusing oil shale ash on an iridium strip heater was used, and the accuracy of the method was assessed by including a standard shale reference material (SGR-1b) in the analysis program.

Step-scan photoacoustic infrared spectroscopy experiments were performed on Green River oil shale samples obtained from the Piceance Basin located in Colorado, USA. We have investigated the molecular nature of light and dark colored areas of the oil shale core using FTIR photoacoustic step-scan spectroscopy. This technique provided us with the means to analyze the oil shale in its original in situ form with the kerogen-mineral interactions intact. All vibrational bands characteristic of kerogen were found in the dark and light colored oil shale samples confirming that kerogen is present throughout the depth of the core. Depth profiling experiments indicated that there are changes between layers in the oil shale molecular structure at a length scale of micron. Comparisons of spectra from the light and dark colored oil shale core samples suggest that the light colored regions have high kerogen content, with spectra similar to that from isolated kerogen, whereas, the dark colored areas contain more mineral components which include clay minerals, dolomite, calcite, and pyrite. The mineral components of the oil shale are important in understanding how the kerogen is "trapped" in the oil shale. Comparing in situ kerogen spectra with spectra from isolated kerogen indicate significant band shifts suggesting important nonbonded molecular interactions between the kerogen and minerals.