Organic Sedimentary Rocks Research Articles

Estimating the Efficiency of Building Stones in Complex Fuzzy Environment

Rocks are importantly used as building materials. Here chemical, biochemical, clastic and organic sedimentary rocks are chosen for building stones. These rocks are tested for their efficiency in structure strength, toughness, weathering resistances and quality. Using complex picture fuzzy soft VIKOR method it is concluded that clastic sedimentary rocks is the best building stone. First a score function is defined and is used for the construction of complex picture fuzzy soft score matrix the proficiency of CPFS score function over the existing score function is established. Next entropy measure is determined from which weight values are calculated. Complex picture fuzzy soft positive and negative ideal solutions are found and hence the group utility and individual regret values are obtained. By making use of these values the compromising ranking solution is found.

The conceptual model of Wae Sano Geothermal field based on geology and geochemistry data

Wae Sano volcano is included in the inner Banda arc, Mount Wae Sano is a type C volcano and formed the Sano Nggoang crater lake. The magmatism activity produces geothermal manifestations such as; hot spring, rock alteration, and sulfur deposits, the hottest water temperature is 81 0C, with neutral pH, but the Sano Nggoang Lake water has acid pH. It becomes interesting to examine the characteristics of the geothermal system in that area. The research was conducted by Volcanostratigraphic studies to reconstruct the geological process and Geochemical sampling of hot springs, lake water, ground air, and the soil side to understand the subsurface characterization. The result showing some period of volcano products, with the youngest come from the product of Sano Nggoang 2 that spills its product to on the north-east side of Poco Dedeng volcano. The geochemical analysis shows all manifestations originate from one reservoir, chloride water type, NaCl type of the lake water with a few SO4 influence, presumably, the hot springs supply is influenced by seawater, the estimation of the reservoir has a temperature about ± 230 0C, with dacite and the rich organic sedimentary rock, and located at ± 1456 m from the manifestation, the isothermal section shows the rate of temperature increase at 97.07 m / 10 0C. The hypothetical resource is counted about 1,488.6 kWe.

El ciclo global del nitrógeno. Una visión para el ecólogo terrestre

Garcia-Velazquez, L., Gallardo, A. 2017. The global nitrogen cycle. A perspective for the terrestrial ecologist. Ecosistemas 26(1): 4-6. Doi.: 10.7818/ECOS.2017.26-1.02 The nitrogen (N) availability in the biosphere, the alteration of the global cycle, and its impact on the ecosystem are given by three key functional characteristics of the N cycle. First, the atmospheric N abundance allows both the biological and industrial fixation through the Haber-Bosch process, doubling the atmospheric N total inputs. Thus, the atmospheric N reservoir is the main source of the N cycle alteration, being the easiness to return to its original compartment the principal difference with the carbon (C) and phosphorus (P) cycles. Second, low concentrations of N in rock and soil minerals determines that in the long-term N limitation is mainly regulated by the biological fixation rate, being also dependent on the soil development and the presence of organic sedimentary rocks. Finally, an essential property of the N cycle in the biosphere is the high mobility of N across ecosystem boundaries through N-fixation, nitrification, denitrification and ammonification processes. All these properties cause that the fixed N molecule have multiples effects along its movement across different ecosystems, leading to acidification, eutrophication, alteration of albedo among other processes, and contributing substantially to climate change.

Geochemistry and health burden of radionuclides and trace metals in shale samples from the North-Western Niger Delta

Organic sedimentary rock samples were collected from three Oil Wells in the North-Western Niger Delta, Nigeria in order to determine their natural radioactivity and elemental geochemistry, with the aim of determining the concentrations of major radionuclides and their radiological and environmental health implication. The PIXE method of IBA technique and an accurately calibrated Si(Li) detector system was used to measure the elemental concentration of the sediment samples. The radionuclides identified belong to the decay series of naturally occurring radionuclides headed by 238U and 232Th along with the non-decay series radionuclide, 40K. The activity concentrations of the radionuclides and their derived dose were then calculated. The average activity concentrations of 40K were 248 Bq/kg for Well A, 261 Bq/kg for Well B and 273 Bq/kg for Well C. For 232Th the activity concentrations were 1,043 Bq/kg for Well A, 1,400 Bq/kg for Well B, 1,434 Bq/kg for Well C. 238U activity concentrations were 2,210, 3,508 and 250 Bq/kg for the Oil Wells A, B, C, respectively. The equivalent dose ranges from 8.5 ± 1.1 to 24.3 ± 2.1 mSv/year with a mean of 14.5 ± 2.2 mSv/year for Oil Well A, 2.4 ± 0.1–75.0 ± 1.2 mSv/year with a mean of 21.5 ± 1.1 mSv/year for Oil Well B and 3.7 ± 0.2–10.7 ± 0.6 mSv/year with a mean of 9.4 ± 2.5 for Oil Well C. The detected trace metals were majorly V, Ni, Pb, Fe, Cr, Cu, Zn, Co and their concentrations together with those of the radionuclides are compared with the relevant world standard limits. The results obtained were high, and hence, the radioactivity level and trace element content of the sediment samples from the North-Western Niger Delta Oil province could constitute health hazard to occupationally exposed workers, and to the public if not properly disposed. However, despite the careful disposal practice claims by the Oil industries, and given the high concentrations, the sediments could still pose an intrinsic health hazard considering their cumulative effects in the environment.

Coupling Effect Between Coalification and Tectonic-thermal Events—Geological Records of Geodynamics of Sedimentary Basin

Coal is an organic sedimentary rock, which is very sensitive to geological factors, such as temperature and pressure. Coalification is actually an open system process in which coal exchanges energy and substance with the surrounding environment. During the long process of geologic evolution, all types of tectonic-thermal activities resulted in the diversification of coal in terms of physics, chemistry, textures, and structures. Affected by various geologic agents, the organic and inorganic components in coal moved, differentiated, and rebuilt, which sequentially influenced the coal seam distribution, coal rank, and coal quality, which can be treated as the geological record of the geodynamics of sedimentary basin to some degree. In this article, research progresses of coupling effects between coalification and tectonic-thermal events at home and abroad are introduced, the main scientific problems are discussed, and some key research projects are proposed.

Supercritical fluid extraction of aliphatic hydrocarbons from Niger Delta sedimentary rock

The extraction of aliphatic hydrocarbons from the Niger Delta sedimentary organic matter by supercritical carbon dioxide at different extraction temperatures and times is described. The study was undertaken in order to determine optimal extraction conditions for the Niger Delta organic sedimentary rock. The results showed that the extraction temperatures (65, 95, 125, 155 and 185 °C) and kinetic rates have a significant effect on extraction yields. The optimum temperature (185 °C) for supercritical fluid extraction of Niger Delta rock was different from that obtained for rock samples from other basins. In comparison with soxhlet extraction, supercritical fluid extraction has better yields; the relative recoveries of the analytes from SFE are about 81–99% in excess of that of soxhlet extraction.

Mineral Matter Distribution on Coal Surface and Its Effect on Coal Wettability

Coal is an organic sedimentary rock composed of organic macerals and mineral matter. As it is demonstrated in this paper the discrete mineralogical nature of coal largely influences the wetting of the coal surface by water. Both advancing and receding contact angles were measured using the captive-bubble technique with an automatic bubble shape analysis software. The distribution and amount of mineral inclusions on the coal surface were determined by scanning electron microscopy and examined using the image analysis system. To determine the amount and size distribution of mineral grains, the coal surface layer, on which the contact angles were measured, was separated from the larger piece used in the measurements by microslicing. The separated surface layer was subjected to a low-temperature ashing followed by particle size analysis. As expected, a significant scatter of contact angle values was obtained for the same coal samples. Increasing the amount of mineral matter on the coal surface reduced the value of both advancing and receding contact angles. Also, the scatter of contact angle values increased with the increasing mineral matter content from about 1 to 50 wt%. The results reveal that an important factor in analysis of contact angle variation on coal surfaces is the size of the hydrophilic mineral inclusions. Both the advancing and the receding contact angles decrease with increasing size of the mineral grains. Additionally, the scatter of contact angle values increase with increasing size of the mineral matter grains. Finally, the results of fractal dimension analysis of mineral matter grains distributed over the coal surface indicate that there is no significant effect from the shape of hydrophilic mineral inclusions on both advancing and receding contact angles.

Evaluation of petroleum generation by hydrous phrolysis experimentation

Generation and expulsion of oil from organic sedimentary rocks have been achieved in the laboratory by a technique known as hydrous pyrolysis. This technique maintains a liquid water phase in contact with organic sedimentary rocks during their heating at subcritical water temperatures (less than 374 °C ). The expelled oil accumulates on the water surface and contains no measurable olefmic hydrocarbons. Hydrous pyrolysis provides a means of acquiring inform ation relating to stages, kinetics an d indices of petroleum generation that would be difficult to obtain from a study of only the natural system

Factors controlling enrichment of vanadium and nickel in the bitumen of organic sedimentary rocks

Enriched concentrations of vanadium and nickel have been noted in a variety of naturally occurring organic substances including crude oils, asphalts, and organic matter in some sedimentary rocks. Vanadium and nickel concentrations in bitumens extracted from a variety of organic sedimentary rock types of different geological ages and geographical areas range from less than 0.2 to 4760 ppm and less than 7 to 1240 ppm, respectively. Vanadium concentrations showed a polymodal frequency distribution, while nickel concentrations showed a near-normal frequency distribution. The concentrations of these two metals showed no significant correlations with bitumen content, organic carbon content, or proportionality between bitumen and organic contents. Enriched vanadium and nickel concentrations greater than 100 ppm are only observed in bitumens that are associated with Type II and Type I kerogens. Conversely, bitumens associated with Type III kerogens contained vanadium and nickel concentrations less than 100 ppm. The high stability of vanadium and nickel in crude oils, asphalts, and bitumens suggest that they occur in tetrapyrrole complexes. These complexes may occur as free molecules or assimulated subunits in macromolecules because of their availability in anaerobic systems, small atomic radii, and favorable electron configurations. The potential for an organic sediment to be enriched in these two metals depends upon the amount of tetrapyrroles preserved in its organic matter. Tetrapyrrole preservation preferentially decreases in organic matter as exposure time to aerobic conditions increases. The potential for vanadium and nickel enrichment is therefore the highest in organic matter derived from algae that encountered anaerobic conditions early in their depositional history. Metallation of tetrapyrrole complexes appears to occur within sediments prior to their lithification, and interstitial waters are the most likely source for enriched concentrations of vanadium and nickel. The amount of metal enrichment in a sediment depends upon the diffusion of metal cations from its overlying water body, and this source is only effective as long as the sediment system remains open. The complete metallation of tetrapyrroles is most favorable under conditions of slow sedimentation rates, which would allow open sediment systems to be maintained for long durations.