scholarly journals Maceral study to determine the desorbed gas content in the Upper Cretaceous coals of the Landázuri area, Middle Magdalena Valley Basin, Colombia

2021 ◽  
Author(s):  
Clara Guatame ◽  
Marco Rincón ◽  
Mauricio Bermúdez
Keyword(s):  
Upper Cretaceous ◽  
Vegetation Index ◽  
Vitrinite Reflectance ◽  
Principal Component ◽  
Sorption Process ◽  
Gas Content ◽  
Coal Seams ◽  
Volume Percentage ◽  
Desorption Process ◽  
Bituminous Coals

Abstract For several decades, some coal petrographic properties have been proposed as important parameters in the methane gas sorption processes. In this contribution, the petrographic variables (Vitrinite Ratio, Inertinite Ratio, the petrographic indexes (Gelification Index, Groundwater Index, Tissue Preservation Index, Vegetation Index, Vitrinite/Inertinite ratio, and the Vitrinite Reflectance were evaluated according to the maceral preservation and were related with the desorbed gas content. Twenty-five coal seams obtained from the drill cores of two wells in the Landázuri Area-Valle Medio del Magdalena basin were analyzed. The coal samples were grouped according to gas content using principal component analysis (PCA). The petrographic results were analyzed by linear regression and multiple regression. The Medium Volatile Bituminous to Low Volatile Bituminous coals from Landázuri 1 are twice as high in gas content that the High Volatile Bituminous A to Medium Volatile Bituminous coals from Landázuri 2. The volume percentage and the preservation degree macerals are related closely to the gas content and the pore's size involved in the sorption process. The Inertinite is the maceral group related with the highest gas content groups in Landázuri (600 SCF-Standard Cubic Feet/ton, 300 SCF/ton), while the other groups show the correspondence with the vitrinite macerals. The syngenetic and diagenetic origin of the pyrite contributes microporosity to the desorption process, while the pyrite epigenetic by its size reduces it. The petrographic indexes reveal that the Upper Cretaceous coals were developed in swampy or lacustrine continental basins- limnic facies.

scholarly journals Controls on Gas Domains and Production Behaviour in A High-Rank CSG Reservoir: Insights from Molecular and Isotopic Chemistry of Co-Produced Waters and Gases from the Bowen Basin, Australia

Geosciences ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 74 ◽  
Author(s):  
Stephanie K. Hamilton ◽  
Suzanne D. Golding ◽  
Joan S. Esterle ◽  
Kim A. Baublys ◽  
Brycson B. Ruyobya
Keyword(s):  
Carbon Isotope ◽  
Vitrinite Reflectance ◽  
Isotope Analysis ◽  
Co2 Reduction ◽  
Production Performance ◽  
High Rank ◽  
Gas Content ◽  
Coal Seams ◽  
Gas Generation ◽  
Geographic Variations

This paper uses hydrochemical and multi-isotope analysis to investigate geological controls on coal seam gas (CSG) saturation domains and gas well production performance in a high-rank (vitrinite reflectance (Rv) > 1.1) CSG field in the north-western Bowen Basin, Australia. New hydrochemical and stable isotope data were combined with existing geochemical datasets to refine hypotheses on the distribution and origins of CSG in two highly compartmentalized Permian coal seams. Stable isotopic results suggest that geographic variations in gas content, saturation and production reflect the extent of secondary microbial gas generation and retention as a function of hydrodynamics. δ13C and δ2H data support a gas mixing hypothesis with δ13C-CH4 increasing from secondary biogenic values to thermogenic values at depth (δ13C −62.2‰ to −46.3‰), whereas correlated methane and carbon dioxide carbon isotope compositions, Δ13C(CO2–CH4) values and δ13CDIC/alkalinity trends are largely consistent with microbial CO2 reduction. In addition, below 200 m, the majority of δ13C-CO2 values are positive (δ13C: −1.2‰ to 7.1‰) and δ13CDIC shows an erratic increase with depth for both seams that is characteristic of evolution via microbial activity. The progression of carbon isotope values along the CO2 reduction fractionation line suggests progressive depletion of the CO2 reservoir with increasing depth. Faults clearly segment coal seams into areas having significantly different production, with results of geochemical analysis suggesting that pooling of biogenic gas and waters and enhanced methanogenesis occur north of a faulted hinge zone.

scholarly journals Vertical and lateral variation of gas content associated with coal seams

2015 ◽  
pp. 49-59
Author(s):  
Luis D. Caro ◽  
Astrid Blandón ◽  
Jorge M. Molina
Keyword(s):  
Coal Seam ◽  
Bituminous Coal ◽  
Direct Relationship ◽  
Vitrinite Reflectance ◽  
Gas Content ◽  
Lateral Variation ◽  
Coal Seams ◽  
Content Variation ◽  
Geological Factors ◽  
Proximal Analysis

Vertical and lateral gas content variation associated within a coal seam and its relation to porosity and geology was researched. Several seams of high sub-bituminous and bituminous coal volatile C from Amaga formation were selected. Channel samples were taken and were subdivided into the different plies (lithotypes associations), performing proximal analysis; Petrographic (maceral counting and determining the vitrinite reflectance); furthermore desorption testing and porosity.The higher gas content was in intermediate plies. It was possible to identify that the gas content, and micropores and mesopores has a direct relationship; also, there is a direct relationship between the content of liptinites macerals and gas content. In some cases, these relationships were not clear, since there is influence of geological factors such as the presence of faults favor migration and degassing of the mantles studied.

scholarly journals Construct a Paleo-Limnological Environment Based on Coal Petrography; Case Study, Two Selected Coal Seams, North Crowsnest Open-Pit Mine, Canada

2021 ◽  
Vol 54 (2D) ◽  
pp. 1-14
Author(s):  
Nader A.A. Edress
Keyword(s):  
Coal Seam ◽  
Vegetation Index ◽  
Vitrinite Reflectance ◽  
Open Pit ◽  
Petrographic Analysis ◽  
Coal Seams ◽  
Water Index ◽  
Average Value ◽  
Coal Facies ◽  
Coal Petrography

The Crowsnest coalfield is a separated structural coalfield at the East Kootenay basin within southeast British Columbia. Selected Jurassic-Cretaceous two coals seam S-10 and S-C of the Mist-Mountain formation were investigated from the points of coal petrography to construct a Paleo-limnological setting. Twenty-two channel coal samples were assembled and measured from S-10 and S-C coal seams. Vitrinite reflectance measuring of the S-10 coal concern to low-volatile bituminous (1.61, on average). While the vitrinite reflectance measurements of S-C coal seam show an average value of 0.98 related to high-volatile bituminous. Petrographic analysis demonstrates that the S-10 coal seam appears to be rich in inertinite than the S-C coal seam that appears rich in vitrinite. Applying coal facies indices of Tissue Preservation Index, Gelification Index, Ground Water Index Vegetation Index and coal facies diagrams for the studied coal seams aid to suggest a condition of the depositional Paleo-environments. The results promote Paleo-depositional sites of telmatic to limno-telmatic setting of rheotropic systems swamp. The obtained results show a trend of increase in both herbaceous flora and anoxic waterlogged limo-telmatic setting toward the younger coal seam S-C than the older S-10 coal seam.

scholarly journals Modeling the Radial Stem Growth of the Pine (Pinus sylvestris L.) Forests Using the Satellite-Derived NDVI and LST (MODIS/AQUA) Data

Atmosphere ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 12
Author(s):  
Yulia Ivanova ◽  
Anton Kovalev ◽  
Vlad Soukhovolsky
Keyword(s):  
Land Surface ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Principal Component ◽  
Stem Growth ◽  
Forest Growth ◽  
Parabolic Approximation ◽  
New Approach ◽  
The Relationship ◽  
Tree Increment

The paper considers a new approach to modeling the relationship between the increase in woody phytomass in the pine forest and satellite-derived Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature (LST) (MODIS/AQUA) data. The developed model combines the phenological and forest growth processes. For the analysis, NDVI and LST (MODIS) satellite data were used together with the measurements of tree-ring widths (TRW). NDVI data contain features of each growing season. The models include parameters of parabolic approximation of NDVI and LST time series transformed using principal component analysis. The study shows that the current rate of TRW is determined by the total values of principal components of the satellite indices over the season and the rate of tree increment in the preceding year.

scholarly journals Role of multiple reflections in the formationof wave field in the cretaceous successions of the Middli Kura depression in Azerbaijan

2021 ◽  
Vol 43 (3) ◽  
pp. 123-134
Author(s):  
T. R. Akhmedov ◽  
T. Kh. Niyazov
Keyword(s):  
Wave Field ◽  
Upper Cretaceous ◽  
Oil And Gas ◽  
Geophysical Methods ◽  
Geological Structure ◽  
Gas Content ◽  
Seismic Exploration ◽  
Time Interval ◽  
Multiple Reflections ◽  
Seismic Sections

The article is devoted to the elucidation of the nature of the wave field recorded below the supporting-dominant seismic horizon «P» in the Middle Kura depression of Azerbaijan. A brief overview of the work carried out here is given; it is indicated that some geologists and geophysicists of our country, in our opinion, mistakenly assume that the observed wave field below the specified horizon is formed mainly by multiple reflections. Since the introduction of the common depth point method into the practice of seismic exploration, individual areas of the Middle Kura depression in Azerbaijan, including the Yevlakh-Agjabedi trough, have been repeatedly studied with varying degrees of frequency tracking. On the basis of this, a fairly large number of promising structures have been identified and mapped. But the structure of the Mesozoic, in particular the deposits of the Upper Cretaceous, still remains insufficiently studied. The study of the geological structure of the Mesozoic sediments, which are considered promising in terms of oil and gas content, is an urgent geological task; exploration work was carried out in the studied areas of the Middle Kura depression using a complex of geophysical methods at the modern technical and methodological level and new results were obtained. The constructed seismic sections show a dynamically pronounced and well-traceable seismic horizon corresponding to the Mesozoic surface and located deeper than it, relatively weak, short, discontinuous reflective boundaries that characterize the structure within the Mesozoic deposits. The studies carried out on the basis of modeling and velocity analysis made it possible to prove that the wave field in the time interval corresponding to the Mesozoic deposits owes its origin to intermittent single reflections from volcanic-carbonate deposits of the Upper Cretaceous age.

Detecting drought conditions related to vegetation at west continental Europe based on variations from the North and Caspian Seas

2021 ◽  
Author(s):  
Bolin Xu ◽  
Qing He ◽  
Kwok Pan Chun ◽  
Julian Klaus ◽  
Rémy Schoppach ◽  
...  
Keyword(s):  
North Sea ◽  
Vegetation Index ◽  
Lower Troposphere ◽  
Principal Component ◽  
Positive Phase ◽  
Vegetation Patterns ◽  
Limited Region ◽  
The North ◽  
The North Sea ◽  
The Impact

<p>Teleconnections relate regional pressure patterns to local climate anomalies, influencing the variation of vegetation patterns. Over west continental Europe, droughts have been widely investigated with persistent low-frequency atmospheric circulation patterns (e.g. the North Atlantic Oscillation, NAO) with the centers over the Atlantic based on the 500mb height anomalies of the Northern Hemisphere. However, the effects of teleconnection patterns with the centers of active variability over the North and Caspian Seas is largely unexplored for droughts related to vegetation patterns. In this study, we explored the impact of the North Sea-Caspian Pattern (NCP) on regional ecohydrologic conditions in the Greater Region of Luxembourg in Western Europe. Using a Principal Component Analysis (PCA), we first decomposed the annual Normalized Difference Vegetation Index (NDVI) from the Global Inventory Monitoring and Modeling System (GIMMS) between 1981 and 2015. In the first PCA component, a distinctive greening trend of NDVI is detected since the late 1980s. However, the corresponding station observations and the ERA5 reanalysis data show that the region in west continental Europe became increasingly drier based on the difference between precipitation and evaporation. We explain the above paradoxical greening but drying patterns by the mechanism of NCP over the region. During the positive phase of NCP, the high pressure over the North Sea weakens circulation over the region and leads to warmer conditions in west continental Europe. These conditions are good for vegetation growth because the region was mainly energy-limited during the observed period at the annual scale based on a Budyko analysis. However, the positive phase of NCP also promotes divergent conditions at the lower troposphere and it reduces moisture flux over the region. In the Budyko space, the persistent positive phase of NCP would lead the energy-limited region to be water-limited. As the positive phase of NCP is expected to be more frequent along with the increasing global temperatures, the region may start to experience increasing water stress on vegetation. These results suggest that unforeseen droughts related to vegetation may be emerging in the region. New drought monitoring and management measures related to vegetation should be developed at west continental Europe, especially during the positive phase of NCP.</p>

Comparative Study of Change Detection and Urban Expansion Using Multi-Date Multi-Source Data: A Case Study of Greater Khartoum

2012 ◽  
Vol 23 (2) ◽  
pp. 139-172
Author(s):  
Abdullah Salman Alsalman Abdullah Salman Alsalman
Keyword(s):  
Image Processing ◽  
Change Detection ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Urban Expansion ◽  
Remote Sensing Data ◽  
Principal Component ◽  
Test Area ◽  
Image Differencing ◽  
Erdas Imagine

Noting that Khartoum represents the most rapidly expanding city in the Sudan and taking into account that change detection operations are seldom , the present study has been initiated to attempt to produce work that synthesizes land use/land cover (LULC) to investigate change detection using GIS, remote sensing data and digital image processing techniques; estimate, evaluate and map changes that took place in the city from 1975 to 2003. The experiment used the techniques of visual inspection, write-function-memoryinsertion, image differencing, image transformation i.e. normalized difference vegetation index (NDVI), tasseled cap, principal component analysis (PCA), post-classification comparison and GIS. The results of all these various techniques were used by the authors to study change detection of the geographic locale of the test area. Image processing and GIS techniques were performed using Intergraph Image analyst 8.4 and GeoMedia professional version 6, ERDAS Imagine 8.7, and ArcGIS 9.2. Results obtained were discussed and analyzed in a comparative manner and a conclusion regarding the best method for change detection of the test area was derived.

scholarly journals Drought Stress Detection in Juvenile Oilseed Rape Using Hyperspectral Imaging with a Focus on Spectra Variability

2020 ◽  
Vol 12 (20) ◽  
pp. 3462
Author(s):  
Wiktor R. Żelazny ◽  
Jan Lukáš
Keyword(s):  
Drought Stress ◽  
Hyperspectral Imaging ◽  
Oilseed Rape ◽  
Treatment Effects ◽  
Vegetation Index ◽  
Principal Component ◽  
Hyperspectral Data ◽  
Stress Detection ◽  
Mean Values ◽  
Standard Deviations

Hyperspectral imaging (HSI) has been gaining recognition as a promising proximal and remote sensing technique for crop drought stress detection. A modelling approach accounting for the treatment effects on the stress indicators’ standard deviations was applied to proximal images of oilseed rape—a crop subjected to various HSI studies, with the exception of drought. The aim of the present study was to determine the spectral responses of two cultivars, ‘Cadeli’ and ‘Viking’, representing distinctive water management strategies, to three types of watering regimes. Hyperspectral data cubes were acquired at the leaf level using a 2D frame camera. The influence of the experimental factors on the extent of leaf discolorations, vegetation index values, and principal component scores was investigated using Bayesian linear models. Clear treatment effects were obtained primarily for the vegetation indexes with respect to the watering regimes. The mean values of RGI, MTCI, RNDVI, and GI responded to the difference between the well-watered and water-deprived plants. The RGI index excelled among them in terms of effect strengths, which amounted to −0.96[−2.21,0.21] and −0.71[−1.97,0.49] units for each cultivar. A consistent increase in the multiple index standard deviations, especially RGI, PSRI, TCARI, and TCARI/OSAVI, was associated with worsening of the hydric regime. These increases were captured not only for the dry treatment but also for the plants subjected to regeneration after a drought episode, particularly by PSRI (a multiplicative effect of 0.33[0.16,0.68] for ‘Cadeli’). This result suggests a higher sensitivity of the vegetation index variability measures relative to the means in the context of the oilseed rape drought stress diagnosis and justifies the application of HSI to capture these effects. RGI is an index deserving additional scrutiny in future studies, as both its mean and standard deviation were affected by the watering regimes.

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