Carbone organique: indicateur potentiel de paléoenvironnements; deux exemples

1981 ◽  
Vol 18 (12) ◽  
pp. 1838-1849 ◽  
Author(s):  
R. Bertrand ◽  
Y. Héroux
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Total Organic Carbon ◽  
Sedimentary Rock ◽  
Depositional Environment ◽  
Statistical Processing ◽  
Depositional Environments ◽  
The Other ◽  
Early Paleozoic

The paleoenvironment of deposition and the total organic carbon (TOC) content of two sedimentary rock sequences are studied. One has a Cenozoic age and is located on the Labrador shelf; the other is early Paleozoic and is found in the St. Lawrence Lowlands. In both sequences, variations in the paleoenvironments correspond to changes in the TOC content, despite important differences between them (age, tectonic and general paleogeographic contexts, lithologies, nature of the organic matter).A statistical processing of the data is used in order to show this parallelism between the paleoenvironment and the TOC content. In both cases, the higher the TOC content, the greater is the distance of the depositional environment from the shore. This result is in agreement with the conclusions of many other authors. This method may be very useful for detecting bathymetric variations in depositional environments, especially in monotonous sequences.

scholarly journals Organic geochemical characteristics and depositional environments of the Jurassic shales in the Masila Basin of Eastern Yemen

GeoArabia ◽  
2011 ◽  
Vol 16 (1) ◽  
pp. 47-64 ◽  
Author(s):  
Mohammed H. Hakimi ◽  
Wan H. Abdullah ◽  
Mohamed R. Shalaby
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Total Organic Carbon ◽  
Organic Matter Content ◽  
Depositional Environments ◽  
Mature Stage ◽  
Organic Carbon Content ◽  
Type I ◽  
Type Ii ◽  
High Hydrogen

ABSTRACT In this paper, organic matter content, type and maturity as well as some petrographic characteristics of the Jurassic shales exposed in the Masila Basin were evaluated and their depositional environments were interpreted using organic geochemical and organic petrological studies. The total organic carbon (TOC) contents of shales in the Sunah, Wadi Taribah, and Kharir fields vary between 2.4% and 4.7% with high Hydrogen Index (HI) values. All shale samples display very low Oxygen Index (OI) values. The Sunah and Wadi Taribah shales contain Type II organic matter, while the Kharir shales contain Type II, with minor contributions from Type I organic matter. Tmax values for the shales range from 428 °C to 438 °C and vitrinite reflectance values (%Ro) range from 0.52% to 0.80%. These values reveal that the Sunah and Kharir shales are at peak mature stage while the Wadi Taribah shales are early mature. This is supported by their biomarker maturity parameters. The pristane/phytane (Pr/Ph) ratios range from 1.8 to 2.3. In addition, all shales show a homohopane distribution which is dominated by low carbon numbers, and C35 homohopane index is very low for all shale samples. All these features may indicate that these shales were deposited in a suboxic environment. Sterane distribution was calculated as C27>C29>C28 from the m/z 217 mass chromatogram for all shale samples. The Sunah, Wadi Taribah and Kharir shales are believed to have good oil generating potential. This is supported by high total organic carbon content, hydrogen indices up to 400 mg HC/g TOC and early to peak mature oil window range.

scholarly journals Evaluation of the hydrocarbon generation potential of the Pimenteiras Formation, Parnaiba Basin (Brazil) based on total organic carbon content and Rock-Eval pyrolysis data

2020 ◽  
pp. 014459872094958
Author(s):  
Agostinho Mussa ◽  
Wolfgang Kalkreuth ◽  
Ana Maria Pimentel Mizusaki ◽  
Marleny Blanco González ◽  
Tais Freitas da Silva ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Total Organic Carbon ◽  
Depositional Environments ◽  
Organic Carbon Content ◽  
Hydrocarbon Generation ◽  
Burial History ◽  
Anoxic Conditions ◽  
Rock Eval ◽  
Parnaíba Basin

The Parnaiba Basin is a Paleozoic to Mesozoic intraplate volcano-sedimentary basin where the Pimenteiras Formation (Devonian) is the main sequence with potential of hydrocarbon generation, mostly natural gas. The present paper evaluates the potential of hydrocarbon generation of Pimenteiras Formation based on Total Organic Carbon (TOC) and Rock-Eval pyrolysis parameters. In this work, 1077 shale samples of the Pimenteiras Formation distributed in 32 wells were evaluated. The TOC content varies between 0.1 to 4.7 wt.%, partially reflecting the accumulation and preservation rates of the organic matter in marine and coastal depositional environments controlled by regressive-transgressive cycles. The oxic and anoxic conditions vary significantly with deposition in this situation, which were evidenced by HI and OI variations through sample profiles. In the north and center of the basin, the Pimenteiras Formation has a higher potential for hydrocarbon generation relative to the south, probably due to higher anoxic conditions during deposition. The Hydrogen Index indicates the predominance of kerogen types II and III with minor occurrences of types I and IV. The Tmax values indicate general immature conditions and locally postmature, where the lowest temperatures represent the basin´s burial history, whereas the higher ones were influenced by igneous intrusions and thermogenic anomalies related to the Transbrasiliano Lineament. In addition, the excessive heat around the intrusions altered the Rock-Eval pyrolysis parameters as well as the type of organic matter, resulting in a relative increase of the kerogen types III and IV, which explains the great potential for gas generation in this basin.

scholarly journals Application of Various Machine Learning Techniques in Predicting Total Organic Carbon from Well Logs

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Osama Siddig ◽  
Ahmed Farid Ibrahim ◽  
Salaheldin Elkatatny
Keyword(s):  
Machine Learning ◽  
Organic Carbon ◽  
Total Organic Carbon ◽  
The Other ◽  
Well Logs ◽  
Machine Learning Techniques ◽  
Percentage Error ◽  
Average Error ◽  
Support Vector ◽  
Empirical Correlations

Unconventional resources have recently gained a lot of attention, and as a consequence, there has been an increase in research interest in predicting total organic carbon (TOC) as a crucial quality indicator. TOC is commonly measured experimentally; however, due to sampling restrictions, obtaining continuous data on TOC is difficult. Therefore, different empirical correlations for TOC have been presented. However, there are concerns about the generalization and accuracy of these correlations. In this paper, different machine learning (ML) techniques were utilized to develop models that predict TOC from well logs, including formation resistivity (FR), spontaneous potential (SP), sonic transit time (Δt), bulk density (RHOB), neutron porosity (CNP), gamma ray (GR), and spectrum logs of thorium (Th), uranium (Ur), and potassium (K). Over 1250 data points from the Devonian Duvernay shale were utilized to create and validate the model. These datasets were obtained from three wells; the first was used to train the models, while the data sets from the other two wells were utilized to test and validate them. Support vector machine (SVM), random forest (RF), and decision tree (DT) were the ML approaches tested, and their predictions were contrasted with three empirical correlations. Various AI methods’ parameters were tested to assure the best possible accuracy in terms of correlation coefficient (R) and average absolute percentage error (AAPE) between the actual and predicted TOC. The three ML methods yielded good matches; however, the RF-based model has the best performance. The RF model was able to predict the TOC for the different datasets with R values range between 0.93 and 0.99 and AAPE values less than 14%. In terms of average error, the ML-based models outperformed the other three empirical correlations. This study shows the capability and robustness of ML models to predict the total organic carbon from readily available logging data without the need for core analysis or additional well interventions.

scholarly journals Characterization of organic matter from a stratigraphic sequence intercepted by the Nemo-1X well, Mozambique: Potential for hydrocarbon generation

2018 ◽  
Vol 36 (5) ◽  
pp. 1157-1171
Author(s):  
Agostinho Mussa ◽  
Deolinda Flores ◽  
Joana Ribeiro ◽  
Ana MP Mizusaki ◽  
Mónica Chamussa ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Total Organic Carbon ◽  
Hydrocarbon Exploration ◽  
Published Data ◽  
Organic Carbon Content ◽  
Hydrocarbon Generation ◽  
Offshore Area ◽  
Type Iii ◽  
Kerogen Type

The Mozambique Basin, which occurs onshore and offshore in the central and southern parts of Mozambique, contains a thick sequence of volcanic and sedimentary rocks that range in age from the Jurassic to Cenozoic. This basin, along with the Rovuma basin to the north, has been the main target for hydrocarbon exploration; however, published data on hydrocarbon occurrences do not exist. In this context, the present study aims to contribute to the understanding of the nature of the organic matter of a sedimentary sequence intercepted by the Nemo-1X exploration well located in the offshore area of the Mozambique Basin. The well reached a depth of 4127 m, and 33 samples were collected from a depth of 2219–3676 m ranging in age from early to Late Cretaceous. In this study, petrographic and geochemical analytical methods were applied to assess the level of vitrinite reflectance and the organic matter type as well as the total organic carbon, total sulfur, and CaCO3 contents. The results show that the total organic carbon content ranges from 0.41 to 1.34 wt%, with the highest values determined in the samples from the Lower Domo Shale and Sena Formations, which may be related to the presence of the solid bitumens that occur in the carbonate fraction of those samples. The vitrinite random reflectances range from 0.65 to 0.86%Rrandom, suggesting that the organic matter in all of the samples is in the peak phase of the “oil generation window” (0.65–0.9%Rrandom). The organic matter is mainly composed of vitrinite and inertinite macerals, with a minor contribution of sporinite from the liptinite group, which is typical of kerogen type III. Although all of the samples have vitrinite reflectances corresponding to the oil window, the formation of liquid hydrocarbons is rather limited because the organic matter is dominated by gas-prone kerogen type III.

Particulate organic matter in soil under different management systems in the Brazilian Cerrado

Soil Research ◽  
2012 ◽  
Vol 50 (8) ◽  
pp. 685 ◽  
Author(s):  
Arcângelo Loss ◽  
Marcos Gervasio Pereira ◽  
Adriano Perin ◽  
Fernando Silva Coutinho ◽  
Lúcia Helena Cunha dos Anjos
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Organic Carbon ◽  
The Other ◽  
Management Systems ◽  
Soil Conditions ◽  
Brazilian Cerrado ◽  
Cerrado Vegetation ◽  
No Till ◽  
Planting System

The combination of the no-till planting system (NTS) and pasture (e.g. brachiaria grass, Urochloa sp.) for livestock production constitutes a crop–livestock integration (CLI) system. CLI systems significantly increase the total organic carbon (TOC) content of soil and the particulate organic carbon (POC) of soil organic matter (SOM). The present study evaluated TOC and the granulometric fractions of SOM under different management systems in a Cerrado area in the state of Goiás. Two areas applying crop rotation were evaluated, one using CLI (corn/brachiaria grass/bean/cotton/soybean planted sequentially) and the other NTS (sunflower/pearl millet/soybean/corn planted sequentially). A third area covered with natural Cerrado vegetation (Cerradão) served as a reference to determine original soil conditions. Soil was randomly sampled at 0–5, 5–10, 10–20, and 20–40 cm. The TOC, POC, and mineral-associated organic carbon (MOC) were assessed, and POC and MOC stocks calculated. The CLI system resulted in greater TOC levels than NTS (0–5, 5–10, and 10–20 cm). Compared with the Cerradão, CLI areas exhibited higher stocks of TOC (at 5–10 and 10–20 cm) and POC (at 0–40 cm). Results obtained for TOC and POC fractions show that land management with CLI was more efficient in increasing SOM than NTS. Moreover, when compared with NTS, the CLI system provided better POC stratification.

OIL GEOCHEMISTRY AND POTENTIAL SOURCE ROCKS OF THE OFFICER BASIN, SOUTH AUSTRALIA

1980 ◽  
Vol 20 (1) ◽  
pp. 68 ◽  
Author(s):  
D.M. McKirdy ◽  
A.J. Kantsler
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Carbonate Rocks ◽  
Depositional Environment ◽  
South Australia ◽  
Source Rocks ◽  
Potential Source ◽  
Playa Lake ◽  
Oil Source ◽  
Extractable Organic Matter

Oil shows observed in Cambrian Observatory Hill Beds, intersected during recent stratigraphic drilling of SADME Byilkaoora-1 in the Officer Basin, indicate that oil has been generated within the basin. Shows vary in character from "light" oils exuding from fractures through to heavy viscous bitumen in vugs in carbonate rocks of a playa-lake sequence.The oils are immature and belong to two primary genetic families with some oils severely biodegraded. The less altered oils are rich in the C13 - C25 and C30 acyclic isoprenoid alkanes. Source beds within the evaporitic sequence contain 0.5 - 1.0% total organic carbon and yield up to 1900 ppm solvent-extractable organic matter. Oil-source rock correlations indicate that the oils originated within those facies drilled; this represents the first reported examples of non-marine Cambrian petroleum. The main precursor organisms were benthonic algae and various bacteria.Studies of organic matter in Cambrian strata from five other stratigraphic wells in the basin reveal regional variations in hydrocarbon source potential that relate to differences in precursor microbiota and/or depositional environment and regional maturation. Micritic carbonates of marine sabkha origin, located along the southeast margin of the basin, are rated as marginally mature to mature and good to prolific sources of oil. Further north and adjacent to the Musgrave Block, Cambrian siltstones and shales have low organic carbon values and hydrocarbon yields, and at best are only marginally mature. Varieties of organic matter recognised during petrographic studies of carbonates in the Officer Basin include lamellar alginite (alginite B) and "balls" of bitumen with reflectance in the range 0.2 to 1.4%.

scholarly journals Sources and export of particle-borne organic matter during a monsoon flood in a catchment of northern Laos

2015 ◽  
Vol 12 (4) ◽  
pp. 1073-1089 ◽  
Author(s):  
E. Gourdin ◽  
S. Huon ◽  
O. Evrard ◽  
O. Ribolzi ◽  
T. Bariac ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Total Organic Carbon ◽  
Particulate Organic Matter ◽  
Rainy Season ◽  
Overland Flow ◽  
Specific Yield ◽  
Main Stream ◽  
Δ13c And Δ15n ◽  
Suspended Organic Matter

Abstract. The yields of the tropical rivers of Southeast Asia supply large quantities of carbon to the ocean. The origin and dynamics of particulate organic matter were studied in the Houay Xon River catchment located in northern Laos during the first erosive flood of the rainy season in May 2012. This cultivated catchment is equipped with three successive gauging stations draining areas ranging between 0.2 and 11.6 km2 on the main stem of the permanent stream, and two additional stations draining 0.6 ha hillslopes. In addition, the sequential monitoring of rainwater, overland flow and suspended organic matter compositions was conducted at the 1 m2 plot scale during a storm. The composition of particulate organic matter (total organic carbon and total nitrogen concentrations, δ13C and δ15N) was determined for suspended sediment, soil surface (top 2 cm) and soil subsurface (gullies and riverbanks) samples collected in the catchment (n = 57, 65 and 11, respectively). Hydrograph separation of event water was achieved using water electric conductivity and δ18O measurements for rainfall, overland flow and river water base flow (n = 9, 30 and 57, respectively). The composition of particulate organic matter indicates that upstream suspended sediments mainly originated from cultivated soils labelled by their C3 vegetation cover (upland rice, fallow vegetation and teak plantations). In contrast, channel banks characterized by C4 vegetation (Napier grass) supplied significant quantities of sediment to the river during the flood rising stage at the upstream station as well as in downstream river sections. The highest runoff coefficient (11.7%), sediment specific yield (433 kg ha−1), total organic carbon specific yield (8.3 kg C ha−1) and overland flow contribution (78–100%) were found downstream of reforested areas planted with teaks. Swamps located along the main stream acted as sediment filters and controlled the composition of suspended organic matter. Total organic carbon specific yields were particularly high because they occurred during the first erosive storm of the rainy season, just after the period of slash-and-burn operations in the catchment.

scholarly journals Chemical and physical fractions of soil organic matter under various management regimes in Roraima, Brazil

2017 ◽  
Vol 38 (4Supl1) ◽  
pp. 2419
Author(s):  
Marden Daniel Espinoza Guardiola ◽  
José Frutuoso Vale Júnior ◽  
Edmilson Evangelista da Silva ◽  
Celeste Queiroz Rossi ◽  
Marcos Gervasio Pereira
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Organic Carbon ◽  
Chemical Elements ◽  
The Other ◽  
Management Systems ◽  
Natural Fertility ◽  
Chemical Attributes ◽  
Pasture Area ◽  
Physical And Chemical

The crop-livestock integration (CLI) and crop-livestock-forest integration (CLFI) management systems, have been shown to be viable approaches for increasing carbon sequestration in soils, resulting in the improvement of physical and chemical soil attributes. The objective of this study was to evaluate the chemical attributes and organic matter in soils under Natural Forest (NF) converted to different uses and managed differently: rotational pasture area (PAST), crop-livestock integration (CLI), and crop-livestock-forest integration (CLIF). The research was conducted at the São Paulo farm, in Iracema, located in the south-central region of the state of Roraima, Brazil. The studied soil type was classified as Ultisol. Soil samples were taken by opening ditches and examining layers at 0.1-m depth intervals from surface to 0.60-m depth. Total organic carbon (TOC), chemical and granulometric fractionation of soil organic matter (SOM), oxidizable fractions, and light organic matter in water were analyzed. Our results showed low levels of the analyzed chemical elements, a characteristic of a soil with low natural fertility. This matches conditions inherent in source material, weathered by high rainfall, a warm and humid climate, and flat topographic relief. In the 0-0.1 m layer, the PAST and CLI systems had the highest TOC contents relative to the other systems studied. At other depths, there were no statistical differences among TOC levels. The highest concentration of C in the particulate fraction (POC) was noted in the surface layer in all management systems. The pasture system had the highest concentration POC in the top 0.10 m. Our results also showed that the upper 0.10 m of soil in NF contained the lowest content of organic carbon associated with mineral (MOC) relative to the managed agrosystems. In addition, humin provided the largest contribution to SOM in all evaluated management systems. The crop-livestock integration (CLI) and crop-livestock integration forest (CLIF) systems, emerged as a strong alternative to carbon incorporation and subsequently the improvement of physical and chemical soil attributes. The objective of this work to evaluate the chemical attributes and organic matter in soils under Natural forest (NF) converted into different use and management systems: pasture (PAST), crop-livestock Integration (CLI) and crop-livestock Integration forest (CLIF). The research was conducted at São Paulo farm in Iracema, located in the Center-South region of the State of Roraima, Brazil. The soil studied was classified as Argissolo Amarelo Distrófico. The samples were taken by the opening of trenches in layers of 0-0.10, 0.10- 0.20, 0.20- 0.40, and 0.40-0.60 m depth. Total organic carbon (TOC), chemical and granulometric fractionation of soil organic matter (SOM), oxidizable fractions and organic matter in water were analyzed. The results showed low levels of the analyzed chemical elements which characterizes soils with low natural fertility, which matches the conditions of the source material, high rainfall and regional temperature, as well as the flat local relief. In the 0-0.1 m layer, the PAST and CLI systems had the highest TOC contents when compared to the other systems studied, in the other depths there were no statistical differences between the TOC levels. The highest amount of C in the particulate fraction (COp) was verified in the surface layer in all evaluated management systems. The pasture area was the system with the greatest contribution of COp to the depth of 0-0.0 m. In relation to the carbon content associated with minerals (COam), the results showed that the depth of 0-0.05 m NF area presented the lowest levels when compared to the other systems. Regarding the humic substances, there was a larger contribution of humin in all evaluated systems.

scholarly journals Depositional environment and pore structure of mixed lithofacies shale of the Longmaxi Formation in the DM Block, the Southern Sichuan Basin, China

2019 ◽  
Vol 38 (3) ◽  
pp. 629-653 ◽  
Author(s):  
Jijun Tian ◽  
Chuanzheng Xu ◽  
Xin Li ◽  
Wenfeng Wang ◽  
Wen Lin
Keyword(s):  
Organic Carbon ◽  
Total Organic Carbon ◽  
Sichuan Basin ◽  
Depositional Environment ◽  
Sedimentary Environment ◽  
Nitrogen Adsorption ◽  
X Ray Diffraction ◽  
Low Field ◽  
Water Wetting ◽  
Longmaxi Shale

Distinguishing the differences of pore characters between different mixed lithofacies shales is helpful for improving shale gas development efficiencies. In this study, the targeted Longmaxi shale ( L1) of the Southern Sichuan Basin was selected as the research object. Two kinds of mixed lithofacies shale were identified by analyzing total organic carbon and X-ray diffraction results. The forming depositional environment of mixed lithofacies shale was researched by elements analyses. Pores in different mixed lithofacies shale were observed using field emission scanning electronic microscope. Low-field nuclear magnetic resonance and low-temperature nitrogen adsorption were conducted to analyze pore characters of different mixed lithofacies shale. The results showed that L1 were mainly composed of organic rich clay–siliceous mixed shales (OR-M-1) and organic extreme rich calcareous–siliceous mixed shales (OER-M-3). OR-M-1 and OER-M-3 were formed in high paleo-producing dysoxic–oxic seawater and anoxic waterbody, respectively. Micro-pore and meso-pore volumes of OER-M-3 were greater than those of OR-M-1 while macro-pore volume of OER-M-3 was lower than that of OR-M-1. Meso-pore surficial and structural complexities of OER-M-3 were greater than those of OR-M-1. OER-M-3 were greater in oil-wetting micro-pore structural complexities while lower in water-wetting micro-pore structural complexities, compared with OR-M-1. The inherent relationships between lithofacies type and sedimentary environment, total organic carbon, as well as pore characters, respectively, were quite close.

scholarly journals Development of Upwelling during the Sedimentary Period of the Organic-Rich Shales in the Wufeng and Longmaxi Formations of the Upper Yangtze Region and Its Impact on Organic Matter Enrichment

2019 ◽  
Vol 7 (4) ◽  
pp. 99 ◽  
Author(s):  
Shao-Ze Zhao ◽  
Yong Li ◽  
Hua-Jun Min ◽  
Tong Wang ◽  
Zhou Nie ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Total Organic Carbon ◽  
Biogenic Silica ◽  
Vertical Direction ◽  
Burial Depth ◽  
Mineral Component ◽  
Longmaxi Formation ◽  
Component Content ◽  
Upwelling Intensity

This study uses logging data, mineral component content, total organic carbon (TOC) content, and microscopic characteristics of the organic-rich shales in the Wufeng and Longmaxi Formations, as well as data reported by other researchers, to demonstrate that upwelling has played an important role in the organic matter enrichment. The results show that (1) the organic-rich shales of Well N211 in the Upper Yangtze region are located in the Wufeng Formation and the lower Longmaxi Formation, with a burial depth between 2308–2357 m. (2) The organic-rich shales are enriched in biogenic silica. (3) Based on paleogeographic location and characteristics of organisms, this study determines that upwelling occurred during the deposition of the organic-rich shales in the Wufeng and Longmaxi Formations, promoting the enrichment of organic matter in the shales. (4) The upwelling intensity gradually increased from the sedimentary period of the organic-rich shales in the mid-lower Wufeng Formation to the sedimentary period of the Guanyinqiao Member, and then decreased gradually from the sedimentary period of the Guanyinqiao Member to the sedimentary period of the organic-rich shales in the Longmaxi Formation, and leads to the different enrichment of organic matter in the vertical direction. The different developments of upwelling led to the coexistence of both high and low TOC contents in the Guanyinqiao Member along the vertical direction.

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