Oil Shale Seams Research Articles

Influence of high-frequency lake level fluctuations on organic matter accumulation in the northern Qaidam Basin, NW China: Insights from spectral attribute analysis and geochemistry

Assemblages of multiple organic matter-rich sedimentary energy carriers are frequently found in Jurassic nonmarine basins of China. These basins are strongly influenced by high-frequency fluctuations in lake levels. A series of coal- and oil shale-bearing successions reflecting periodic lake level variations is also present in the Shimengou Formation, northern Qaidam Basin, NW China. These Middle Jurassic coal and oil shale seams provide an excellent basis for studying the effects of high-frequency lake level fluctuations on organic matter accumulation. Moreover, additional factors influencing the primary organic matter input (e.g., wildfires) and its preservation and later diagenetic transformation (e.g., processes during coalification) must be considered. In the present study, organic matter maturity, source potential, and paleoenvironmental conditions during source rock formation are investigated based on macro- and micropetrographic data, proximate analyses, bulk geochemical parameters, biomarker analyses, stable isotope geochemistry, and spectral attribute analysis to provide a sequence stratigraphic framework for the accumulation of organic-rich intervals. According to the established depositional model, the Shimengou Formation can be subdivided into four depositional sequences, including three organic matter-rich intervals. These include the thick mixed gas- and oil-prone Sq1 coal seam with a relatively high ash yield, which represents a highstand systems tract, the gas-prone Sq3 coal seam corresponding to a transgressive systems tract, and the Sq4 oil shale layers likely corresponding to a subsequent highstand systems tract, indicating a drowned mire. The results provide insights for the optimization of high-quality sedimentary mineral resource production in similar basins worldwide.

Illuminating and optimising a three‐dimensional model of an oil shale seam and its volume distribution using the transient electromagnetic induction method, central part of Jordan

ABSTRACTThe oil shale exploration program in Jordan is undertaking great activity in the domain of applied geophysical methods to evaluate bitumen‐bearing rock. In the study area, the bituminous marl or oil shale exhibits a rock type dominated by lithofacies layers composed of chalky limestone, marls, clayey marls, and phosphatic marls.The study aims to present enhancements for oil shale seam detection using progressive interpretation from a one‐dimensional inversion to a three‐dimensional modelling and inversion of ground‐based transient electromagnetic data at an area of stressed geological layers.The geophysical survey combined 58 transient electromagnetic sites to produce geoelectrical structures at different depth slices, and cross sections were used to characterise the horizon of the most likely sites for mining oil shale. The results show valuable information on the thickness of the oil shale seam at 3.7 Ωm, which is correlated to the geoelectrical layer between 2‐ and 4 ms transient time delays, and at depths ranging between 85 and 105 m. The 300 m penetrated depth of the transient electromagnetic soundings allows the resolution of the main geological units at narrow resistivity contrast and the distinction of the main geological structures that constrain the detection of the oil shale seam. This geoelectrical layer at different depth slices illustrates a localised oil shale setting and can be spatially correlated with an area bounded by fold and fault systems. Also, three‐dimensional modelling and inversion for synthetic and experimental data are introduced at the faulted area. The results show the limitations of oil shale imaging at a depth exceeding 130 m, which depends on the near‐surface resistivity layer, the low resistivity contrast of the main lithological units, and the degree of geological detail achieved at a suitable model's misfit value.

OCCURRENCE AND ENRICHMENT OF TRACE ELEMENTS IN MARINE OIL SHALE (CHINA) AND THEIR BEHAVIOUR DURING COMBUSTION

The Shengli River-Changshe Mountain oil shale zone represents the potentially largest marine oil shale resource in China. With the aim to have better knowledge of the distribution of trace elements in oil shale, and their behaviour during oil shale combustion and gasification, 28 raw Changliang Mountain oil shale and marl samples, 19 oil shale combustion residue samples and 23 samples of minerals isolated from Changliang Mountain oil shale are studied for trace element content. The oil shale samples from the Changshe Mountain area are characterized by high ash yield (54.69-86.75%) and total organic carbon (TOC) content (2.20- 13.44%). The contents of Se, Mo, Cd, As, B, and Ni in raw oil shale samples are 3.78 to 28.44 times their upper continental crust values. The enrichment of an element in oil shale seams may be a function of that association and the origin of oil shale fractions. Some trace elements in the Changshe Mountain oil shale show susceptibility to release into the atmosphere, including about 93% Hg and 20-30% As, Ba, Be, Co, Cr, Nb, and Sc. The behaviour and migration of trace elements during oil shale combustion strongly depend on their mode of occurrence in the rock. Based on Pearson's coefficients of correlation between elements, as well as cluster and isolated mineral analyses, the main modes of occurrence of trace elements in marine oil shale are distinguished: 1) clay mineral affined - B, Ba, Be, Cr, Cs, Ga, Hf, Li, Nb, Rb, Sc, Sn, Ta, Th, V, W, Zr, REEs; 2) organic affined - As, Mo, Se; 3) Fe-bearing mineral affined - Bi, Co, Cu, Ni, Pb, U; 4) calcite affined - Cd, Sr and 5) fossil affined - Cd, Zn.

Volcanism, sedimentation, K/Ar and palynology studies, Yayu and Delbi-Moye Basins, Southwestern Plateau of Ethiopia

Major element, K/Ar, sedimentation and palynology data are reported on Tertiary volcanic and sedimentary rocks from the Yayu and Delbi-Moye Basins, SW Ethiopia. In the Yayu and Delbi-Moye Basins, pre-rift volcanic (basalts) and post-rift volcanic (basalts) are separated by coal and oil shale-bearing sedimentary rocks. The basalts are tholeiitic in composition. The K/Ar data on the volcanic rocks range from 10.98±0.55Ma (Lower Miocene i.e. Tortonian) to 111.19±2.83Ma (Early Cretaceous i.e. Aptian). Inter-Trappean coal and oil shale-bearing sedimentary rocks are widely distributed in the Yayu and Delbi-Moye Basins. The NNW–SSE fault system developed grabens and half-grabens for the deposition of coal and oil shale-bearing sedimentary rocks. The sedimentary successions are dominated by fine to medium-grained sandstones, siltstones, mudstones, carbonaceous shales, carbonaceous claystones, coal and oil shale seams, and are characterized by meandering river and lacustrine depositional environments. Fresh water algae Botryococcus brauni, Pediastrum sp., Polypodii sporites favus and Polypodii sporites afavus and Pachydermites diederixi, are common palynomorphs in the studied coal and oil shales, and are indicators of lacustrine environment. The presence of Peregrinipollis nigericus is consistent with Oligocene to Miocene. The presence of Euphorbiaceae, Papilionacae, Melastomtaceae sp., Dodonaea, Martretia quadricornis, Rubiaceae sp. (pollen derived from tropical shrubs), Sapotaceae spp. and Meliaceae spp. are indicative of humid, tropical rainforest conditions. Extensive bio-assemblages confirm that the age of coal and oil shale-bearing sedimentary rocks to be Oligocene to Miocene.

Geochemistry of platinum group elements in marine oil shale from the Changshe Mountain area (China): Implications for modes of occurrence and origins

Abstract The Shengli River–Changshe Mountain oil shale zone, located in the North Qiangtang depression, northern Tibet plateau, represents a potentially largest marine oil shale resource in China. Eighteen samples, including oil shale and micritic limestone, were collected from the Changshe Mountain oil shale to determine the concentrations, the modes of occurrence, and origins of platinum group elements (PGEs) in marine oil shale. The oil shale samples from the Changshe Mountain area exhibit low total PGE contents ranging from 3.196 to 8.071 ng/g with a weighted mean value of 5.383 ng/g, while the micritic limestone samples from the Changshe Mountain area exhibit a little lower ranging from 0.471 to 5.669 ng/g. PGEs in oil shale samples are characterized by high contents in Pd (3.23 ng/g), Pt (1.60 ng/g), and Os (0.32 ng/g), as compared to Rh (0.083 ng/g), Ru (0.112 ng/g), and Ir (0.043 ng/g). The individual PGEs of oil shale samples from the Changshe Mountain area exhibit various modes of occurrence. Ru and Ir are mainly controlled by clay minerals and partly present as sulfide. Rh is mainly associated with sulfide and possibly present as clay minerals. Pt is associated with clay minerals and sulfide, and Pd is controlled by organic matter and pyrite, while Os is mainly present in organic matter. Three possible sources of PGEs were identified in oil shale seams in the Changshe Mountain area. Ru and Ir are mainly terrigenous inputs. Rh and Pt are derived from mixed sources (seawater and terrigemnous supply), while Pd and Os are mainly derived from seawater. The terrestrial source of the oil shale seams in the Changshe Mountain oil shale was the Suowa Formation limestone and the Nadi Kangri felsic volcanic rocks.

ORIGIN AND MODE OF OCCURRENCE OF TRACE ELEMENTS IN MARINE OIL SHALE FROM THE SHENGLI RIVER AREA, NORTHERN TIBET, CHINA

With the aim of better understanding of geochemistry of marine oil shale, 25 samples from the Shengli River area were studied. The concentrations of Sr, U, Rb, Pb, and Th were 1.22 to 3.66 times higher compared to the average concentrations in the crust (Clarke values), while the concentrations of other elements were slightly higher/lower compared to the respective Clarke values. Trace elements including U, Pb and Th are important from the environmental point of view. The elements in the Shengli River oil shale may be divided into three groups according to their modes of occurrence, i.e. group A, B, and C. Group A exhibits a relatively high affinity with organic matter. Group B has weakly positive or slightly negative correlation coefficients with ash yield, while Group C shows high positive correlation coefficients with ash yield and possibly has an inorganic affinity. Elements related to terrigenous origin in the oil shale seams in the Shengli River oil shale have originated from two sources: the Nadi Kangri Formation felsic volcanic rocks and the Suowa Formation limestone.

Geochemistry and origin of rare earth elements (REEs) in the Shengli River oil shale, northern Tibet, China

The Shengli River-Changshe Mountain oil shale zone, located in the North Qiangtang depression, northern Tibet plateau, represents a potentially large marine oil shale resource in China. Twenty-eight samples including oil shale, micritic limestone and marl were collected from the Shengli River area to determine the contents and distribution patterns of rare earth elements (REEs) in marine oil shale. Oil shale samples from the Shengli River area have high ash yield (61.86–67.48%) and TOC content (8.02–13.67%) with low total sulfur (S t,d) content (0.76–1.39%) and intermediate shale oil content (3.60–16.30%). The total rare earth element (ΣREE) content in oil shale samples is notably depleted (46.79–67.90 μg/g), approximately one third of the mean value of the North American Shale Composite (NASC), and lower than that of world-wide black shales and Chinese coals, but higher than that of world-wide coals and micritic limestone samples (29.21 μg/g) from the Shengli River area. The oil shale samples from the Shengli River area exhibit shale-like Chondrite or NASC-normalized REE patterns similar to those of micritic limestone and marl samples from this area, indicating that REEs of these different lithological samples may have been derived from a similar terrigenous source. REE contents of oil shale samples are highly positive correlated with ash yield and show a positive correlation with Fe and a weakly positive correlation with organic sulfur, and the vertical variations of REEs mainly follow those of Si, Al, K and Ti. All these facts indicate that the REE contents in oil shale seams are mainly controlled by clay minerals and, to a lesser extent, by pyrite, as well as partly associated with oil shale organic constituents. Rare earth elements in the Shengli River oil shale have originated from two sources: a felsic volcanic rock source and a clastic or/and limestone source.

Concentrations and modes of occurrence of platinum group elements in the Shengli River oil shale, northern Tibet, China

The Shengli River–Changshe Mountain oil shale zone, located in the North Qiangtang depression, northern Tibet plateau, represents a potentially large marine oil shale resource in China. Twenty-one samples including oil shale, micritic limestone and marl were collected from the Shengli River area to determine the contents, distribution patterns and modes of occurrence of platinum group elements (PGEs) in marine oil shale. Oil shale samples from the Shengli River area have high ash yield (61.86–67.48%) and total organic carbon content (8.02–13.67%) with low total sulfur content (0.76–1.39%) and intermediate shale oil content (3.60–16.30%). The total PGE content in oil shale samples is very low (average 1.749 ng/g), approximately half the mean value of Chinese coals, but higher than that of USA coals. PGEs in oil shale samples from the Shengli River area are characterized by high Pd (average 0.82 ng/g), Os (average 0.15 ng/g) and Pt (average 0.66 ng/g) contents compared with Ru (average 0.05 ng/g), Rh (average 0.05 ng/g) and Ir (average 0.02 ng/g). Distribution patterns of individual PGEs are not uniform in the Shengli River oil shale section. The lower marl layer is characterized by the highest Ru and Rh concentrations, whereas the upper marl layer is characterized by the highest Os and Ir concentrations. The highest Pt and Pd concentrations are found in the lower and upper parts of oil shale seams, respectively. The individual PGEs in the oil shale samples from the Shengli River area exhibit various modes of occurrence. Ru is mainly present in P-bearing minerals and partly associated with the clay and Ca-bearing minerals. Rh is mainly controlled by clay minerals and partly present in the form of apatite. Os occurs mainly in clay minerals and, to a lesser extent, in pyrite and apatite. Pd and Ir are mainly associated with Ca-bearing minerals and apatite. Pt is mainly present in Ca-bearing minerals and partly related to organic matter and apatite.

GEOCHEMISTRY OF RARE EARTH ELEMENTS IN MARINE OIL SHALE – A CASE STUDY FROM THE BILONG CO AREA, NORTHERN TIBET, CHINA

The Bilong Co oil shale zone is located in the South Qiangtang depression. This zone, together with the Shengli River-Changshe Mountain oil shale zone in the North Qiangtang depression, northern Tibet plateau, represents a potentially large marine oil shale resource in China. The content and modes of occurrence of rare earth elements (REEs) in selected oil shale samples from the Bilong Co area were studied by inductively-coupled plasma mass spectrometer (ICP-MS) and statistical methods, respectively. The total organic carbon (TOC) content (6.75–19.20%) of oil shale samples is high with low or moderate total sulfur (St, d) content (1.05–2.00%) and intermediate shale oil content. The total rare earth element (∑REE) content of oil shale samples ranges from 63.69 to 117.85 µg/g. The average REE content of 13 oil shale samples from the Bilong Co area is slightly higher than that of USA coals and micritic limestone samples from the Bilong Co area, but lower than that of worldwide black shales. The oil shale samples from the Bilong Co area show shale-like chondrite or NASC-normalized REE patterns similar to those of micritic limestone samples from this area, indicating that REEs of these different lithological samples may have been derived from a similar terrigenous source. REE content of oil shale samples is highly positively correlated with ash yield and shows a positive correlation with Fe and a negative correlation with organic sulfur, and the vertical variations of REEs mainly follow those of Si, Al, K, Na and Ti. All these facts indicate that the REE content in oil shale seams is mainly controlled by clay minerals and, to a less extent, by pyrite, as well as partly associated with oil shale organic constituents.

REE geochemistry of marine oil shale from the Changshe Mountain area, northern Tibet, China

Abstract The Shengli River–Changshe Mountain oil shale zone, located in the North Qiangtang depression, northern Tibet plateau, represents a potentially large marine oil shale resource in China. The contents and distribution patterns of rare earth elements (REEs) in selected oil shale and micritic limestone samples from the Changshe Mountain area were studied by inductively-coupled plasma mass spectrometer (ICP-MS). Analyzed oil shale samples from the Changshe Mountain area are characterized by high total organic carbon (TOC) contents (7.02–16.32%) and ash yields (53.22–82.12%) with shale oil contents from 3.85% to 11.76%. The total rare earth element (∑ REE) contents in oil shale samples are 68.19 μg/g, close to those of US coals, and higher than those of micritic limestone samples (37.69 μg/g) from the Changshe Mountain area, but lower than those of world-wide black shales, common Chinese coals, and North American Shale Composite. There are two types, A and B, of distribution patterns of REEs in the Changshe Mountain oil shale samples. Type A shows negligible Ce anomalies (0.97–1.01), with slightly higher ∑ REE concentrations (36.87–118.38 μg/g) and LREE/HREE (6.79–10.74) and (La/Yb) n (6.68–8.36) ratios, whereas type B exhibits a slightly negative Ce anomaly (0.84–0.88), with slightly lower ∑ REE concentrations (13.73–15.31 μg/g) and LREE/HREE (5.54–6.34) and (La/Yb) n (5.03–6.65) ratios. Both types A and B oil shales are characterized by distinctly sloping LREE trends (La n /Sm n = 3.60–5.44) accompanied by flat HREE trends, with distinct Eu negative anomalies (0.51–0.69). The vertical variations of ∑ REE contents are similar to those of ash, Si, Al, K, Na, Ti and Fe, and show a negative correlation with organic sulfur and organic carbon, indicating that the REE contents in oil shale seams are mainly controlled by land-derived detritus.

SEDIMENTOLOGICAL INVESTIGATIONS OF THE SHENGLI RIVER-CHANGSHE MOUNTAIN OIL SHALE (CHINA): RELATIONSHIPS WITH OIL SHALE FORMATION

Recently a new oil shale belt was discovered in the Changshe Mountain area, northern Tibet, China. This belt, combined with the oil shale zone found in the Shengli River area, represents a large marine oil shale resource in China. Three facies associations have been recognized concerning the deposition of oil shale in the Qiangtang basin: fluvial-delta, tidal flat-lagoon and shallow marine facies associations. Oil shales were mainly deposited in lagoonal environments. The deposition of the Shengli River-Changshe Mountain oil shale may be controlled by many factors, such as sea level change, differential palaeotopography and palaeoclimate change. Sea level rise and consequent marine incursion may change the aquatic environment of pre-existing lagoon. Differential palaeotopography may control the lateral distribution of oil shale seam, while palaeoclimate change may be partially responsible for the vertical facies change from oil shale to gypsum-salt deposition.

EVALUATION AND STANDARDIZATION OF ESTONIAN OIL SHALE QUALITY CHARACTERISTICS

The most important mineral wealth of Estonia is oil shale, which is used as fuel for generating electricity, thermal energy, for producing the shale oil, impregnation oil, cement, concrete and other products.Estonian oil shale (Kukersite) deposit occupies an extensive territory (about of 1830 square km). Proved reserves in this deposit were estimated' about 4 billions tons of bil shale. (Fig. 1). The industrial oil shale seam (thickness 2,5 - 3,2 m) contains 6 "oil shale' layers (A - F2) which are separated from one other by limestone intercalation poor in kerogene. The calorific value of oil shale layers ranges between 7-15 MJTkg. The bedding depth of oil shale deposit is from a few meters up to 150 m, now maximum depth in mines are about 70 m. At present oil shale mining is carried out in 6 mines and 3 opencast, oil shale output was 14,6 million tons in 1996.The most important quality characteristics of oil shale are: calorific value Q, moisture W, ash content A, carbonic acid content C02, which have influence on efficiency of using oil shale in power and thermal processing plants and construction materials production. Therefore it is important to elaborate standards of oil shale quality, characteristics and investigate how to guarantine the required for consumers stable quality of oil shale. Checking necessary number of samples from mines, opencasts, power plants and. other consumers, evaluating precision of sampling and determination of quality characteristics is also important.

Expansion of the Commercial Output of Estonian Oil Shale Mining and Processing

Economic and ecological preconditions are considered for the transition from monoproduct oil shale mining to pofyproduct Estonian oil shale deposits. Underground water, limestone, and underground heat found in oil shale mines with smallreserves can be operated for a long time using chambers left after oil shale extraction. The adjacent fields of the closed mines can be connected to the operations of themines that are still working. Complex usage of natural resources of Estonian oilshale deposits is made possible owing to the unique features of its geology andtechnology. Oil shale seam development is carried out at shallow depths (40-70 m) in stable limestones and does not require expensive maintenance. Such naturalresources as underground water, carbonate rocks, heat of rock mass, and underground chambers are opened by mining and are ready for utilization. Room-and-pillar mining does not disturb the surface, and worked oil shale and greenery wasteheaps do not breach its ecology. Technical decisions and economic evaluation arepresented for the complex utilization of natural resources in the boundaries of minetake of the “Tammiku“ underground mine and the adjacent closed mine N2. Ten countries have already experienced industrial utilization of oil shale in small volumes for many years. Usually oil shale deposits are not notable for complex geology of the strata and are not deeply bedded. Thus complex utilization of quite extensive natural resources of Estonian oil shale deposits is of both scientific and practical interest.

Geology of Oil-Shale Deposits Within The Narrows Graben, Queensland, Australia

The Narrows Beds are a Tertiary sedimentary sequence containing oil shale seams, which were deposited in a narrow north-northwest-trending graben. The graben is about 24 mi (38 km) long by 3 mi (5 km) wide and is located adjacent to the central Queensland coast. Two similar oil-shale deposits, Rundle and Stuart containing 5.1 billion bbl of shale oil have been defined within the graben. The Tertiary sedimentary rocks, which were deposited in a freshwater lacustrine environment, are more than 3,280 ft (1,000 m) thick and dip gently westward. They consist of the Worthington beds and the Rundle and Curlew Formations. The Worthington beds range from conglomerate through sandstone to claystone. The Rundle Formation consists of six kerogenous seams and a claystone unit. The sedimentary rocks are consistent throughout the graben. The Curlew Formation is an interbedded sequence of claystone and minor carbonaceous shale. The Worthington beds and the Rundle Formation have been intruded by olivine dolerite, which is not extensive. Quaternary overburden blankets most of the area. Paleontologic studies indicate an early to late Eocene age for the Rundle and Curlew Formations.

XVIII.— Note on Fused Spent Shale from a Retort at Pumpherston, Midlothian

The materials described in this note were submitted by Mr. H. R. J. Conacher of Scottish Oils, Ltd., who thought it possible that the mineral changes occurring in them as a result of thermal action would prove of general interest. One set of specimens (Series I) included lumps of partly fused spent shale and of the contiguous firebrick of the retort wall, and was obtained during the demolition of retorts at Pumpherston. The actual oil-shale which the material represents cannot be definitely identified because the retort had been in operation for some thirty years. The other set of specimens (Series II) consisted of two samples of shale, which had been subjected to a temperature of 1,400° F. in the presence of steam equivalent to 60 gallons of water per ton of shale, one sample (A) having experienced this treatment in presence of air equivalent to about 4,000 c. ft. per ton of shale, the other sample (B) having been treated in the absence of air. A superficially fused SOL brick, which is manufactured from spent shale to which about 10 per cent. of lime has been added, accompanied the samples (A) and (B). The oil-shale seam which the latter represent is not known; but the spent shale from which the SOL brick was made was probably derived from the Pumpherston Shales which contain somewhat more lime and magnesia than the other seams. Series I. The fused shales. —One specimen (S 34619) is composed of fragments of shale embedded in a black This 250-word extract was created in the absence of an abstract