Application of the Fractal Method to the Characterization of Organic Heterogeneities in Shales and Exploration Evaluation of Shale Oil

The first member of the Qingshankou Formation, in the Gulong Sag in the northern part of the Songliao Basin, has become an important target for unconventional hydrocarbon exploration. The organic-rich shale within this formation not only provides favorable hydrocarbon source rocks for conventional reservoirs, but also has excellent potential for shale oil exploration due to its thickness, abundant organic matter, the overall mature oil generation state, high hydrocarbon retention, and commonly existing overpressure. Geochemical analyses of the total organic carbon content (TOC) and rock pyrolysis evaluation (Rock-Eval) have allowed for the quantitative evaluation of the organic matter in the shale. However, the organic matter exhibits a highly heterogeneous spatial distribution and its magnitude varies even at the millimeter scale. In addition, quantification of the TOC distribution is significant to the evaluation of shale reservoirs and the estimation of shale oil resources. In this study, well log data was calibrated using the measured TOC of core samples collected from 11 boreholes in the study area; the continuous TOC distribution within the target zone was obtained using the △logR method; the organic heterogeneity of the shale was characterized using multiple fractal models, including the box-counting dimension (Bd), the power law, and the Hurst exponent models. According to the fractal dimension (D) calculation, the vertical distribution of the TOC was extremely homogeneous. The power law calculation indicates that the vertical distribution of the TOC in the first member of the Qingshankou Formation is multi-fractal and highly heterogeneous. The Hurst exponent varies between 0.23 and 0.49. The lower values indicate higher continuity and enrichment of organic matter, while the higher values suggest a more heterogeneous organic matter distribution. Using the average TOC, coefficient of variation (CV), Bd, D, inflection point, and the Hurst exponent as independent variables, the interpolation prediction method was used to evaluate the exploration potential of the study area. The results indicate that the areas containing boreholes B, C, D, F, and I in the western part of the Gulong Sag are the most promising potential exploration areas. In conclusion, the findings of this study are of significant value in predicting favorable exploration zones for unconventional reservoirs.

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Organic matter heterogeneity and shale oil significance in Triassic Zhangjiatan shale, Ordos Basin, China

Energy Exploration & Exploitation ◽

10.1177/01445987211039382 ◽

2021 ◽

pp. 014459872110393

Author(s):

Xiaoyan Li ◽

Jincai Tuo ◽

Chenjun Wu ◽

Honggang Xin ◽

Mingfeng Zhang ◽

...

Keyword(s):

Organic Matter ◽

Vertical Profile ◽

Sedimentary Environment ◽

Ordos Basin ◽

Immature Stage ◽

Source Rocks ◽

Organic Carbon Content ◽

Shale Oil ◽

Oil Resources ◽

Geochemical Analyses

Organic matter heterogeneity exerts an important impact on the generation, evaluation, and exploitation of shale oil resources. In the past, only a limited number of analytical samples that represented the contribution or influence of high or low organic matter abundance intervals were used to represent an entire set of thick source rocks, and based on this limitation, occasionally researchers have reached incorrect conclusions. Here, the heterogeneity of organic matter and its significance to shale oil in the Triassic Zhangjiatan shale of the Ordos Basin were discussed based on sedimentary and geochemical analyses. Our results indicate that (1) the Chang 73 shale within the study area is characterized by high abundance, good quality, strong heterogeneity, and segmented enrichment in the vertical profile. The primary organic matter type was type II1, and this was followed by types I, II2, and III that exhibited three changing trends in the vertical profile. Organic matter maturity is primarily at the immature stage. (2) Additionally, we observed that the organic matter heterogeneity of Chang 73 shale was related to changes in lithology, sedimentary environment, paleoproductivity, terrigenous influence, and event action (such as volcanism and hydrothermal processes). The abundance of organic matter is the result of the coupling control of these processes. In the process of organic matter deposition, if volcano or hydrothermal activities occurred, the organic matter was abnormally enriched, and the total organic carbon content exceeded 20% and could even be as high as 40%. (3) Finally, we observed at least nine enrichment layers that were controlled by the coupling of different geological factors, and there were four potential target resource layers corresponding to the hydrothermal sedimentary area.

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

Energy Exploration & Exploitation ◽

10.1177/0144598717753920 ◽

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.

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The effect of organic matter type and organic carbon content on Rock-Eval hydrogen index in oil shales and source rocks

Organic Geochemistry ◽

10.1016/0146-6380(87)90068-4 ◽

1987 ◽

Vol 11 (5) ◽

pp. 351-369 ◽

Cited By ~ 19

Author(s):

C Hartman-Stroup

Keyword(s):

Organic Matter ◽

Organic Carbon ◽

Carbon Content ◽

Hydrogen Index ◽

Source Rocks ◽

Organic Carbon Content ◽

Organic Matter Type ◽

Oil Shales ◽

Rock Eval

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Vertical Distributions in Number of Soil Microorganism with Caragana in the Hobq of Inner Mongolia

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.955-959.3581 ◽

2014 ◽

Vol 955-959 ◽

pp. 3581-3585

Author(s):

Xiao Tong Wu ◽

Ya Ting Dai ◽

Yu Qin Shao ◽

Jia Yin Lu ◽

Miao Miao Hou

Keyword(s):

Organic Matter ◽

Vertical Distribution ◽

Inner Mongolia ◽

Soil Microorganisms ◽

Soil Microorganism ◽

Aerobic Bacteria ◽

Vertical Distributions ◽

The Vertical Distribution

The study investigated the vertical distribution of soil microorganism on Caragana rhizosphere at Hobq of ORDOS. The result showed that microbial vertical distribution was obvious. The order of vertical distribution in number of aerobic bacteria were 0-10cm>20-30cm>10-20cm>30-40cm, and there were significant differences between microorganisms in 0-10cm, 10-20cm and 30-40cm underground; the number of aerobic bacteria in 0-10cm underground was higher than 10-20cm, 20-30cm and 30-40cm by 1.48,1.41 and 1.86. The order of vertical distribution in number of fungi were 0-10cm>10-20cm>20-30cm>30-40cm, and there were significant differences between 0-10 cm and 20-30cm、30-40cm, and between 10-20 cm and 20-30cm、30-40cm. the number of fungi in 0-10cm underground was higher than 10-20cm, 20-30cm and 30-40cm by 1.01, 3.60 and 5.37. The order of vertical distribution in number of Actinomycetes was 0-10cm>10-20cm>20-30cm>30-40cm, and the differences between 0-10 cm and 10-20cm, 20-30cm, 30-40cm were significant; the number of Actinomycetes in 0-10cm underground was higher than 10-20cm, 20-30cm and 30-40cm by 1.54,1.66 and 2.60. The distribution and quantity of soil microorganisms might be influenced by organic matter contents.

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Vertical distribution of sub-micron aerosol chemical composition from North-Western Europe and the North-East Atlantic

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-9-9117-2009 ◽

2009 ◽

Vol 9 (2) ◽

pp. 9117-9150

Author(s):

W. T. Morgan ◽

J. D. Allan ◽

K. N. Bower ◽

G. Capes ◽

J. Crosier ◽

...

Keyword(s):

Organic Matter ◽

Chemical Composition ◽

Vertical Distribution ◽

Western Europe ◽

Vertical Profiles ◽

East Atlantic ◽

Air Masses ◽

North East ◽

The North ◽

The Vertical Distribution

Abstract. A synthesis of UK based airborne in-situ measurements of aerosol properties representing air masses from North-West Europe and the North-East Atlantic is presented. The major focus of the study is the vertical distribution of sub-micron aerosol chemical composition. Vertical profiles are derived from a Quadrupole Aerosol Mass Spectrometer (Q-AMS). Background sub-micron aerosol vertical profiles are identified and are primarily composed of organic matter and sulphate aerosol. Such background conditions occurred predominantly during periods associated with long-range air mass transport across the Atlantic. These instances may serve as useful model input of aerosol to Western Europe. Increased mass concentration episodes are coincident with European outflow and periods of stagnant/recirculating air masses. Such periods are characterised by significantly enhanced concentrations of nitrate aerosol relative to those of organic matter and sulphate. Periods of enhanced ground level PM2.5 loadings are coincident with instances of high nitrate mass fractions measured on-board the aircraft, indicating that nitrate is a significant contributor to regional pollution episodes. The vertical structure of the sulphate and organic aerosol profiles were shown to be primarily driven by large-scale dynamical processes. The vertical distribution of nitrate is likely determined by both dynamic and thermodynamic processes, with chemical partitioning of gas phase precursors to the particle phase occurring at lower temperatures at the top of the boundary layer. Such effects have profound implications for the aerosol's lifetime and subsequent impacts, highlighting the requirement for accurate representation of the aerosol vertical distribution.

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Upper Jurassic–Lower Cretaceous Source Rocks in the North of Western Siberia: Comprehensive Geochemical Characterization and Reconstruction of Paleo-Sedimentation Conditions

Geosciences ◽

10.3390/geosciences11080320 ◽

2021 ◽

Vol 11 (8) ◽

pp. 320

Author(s):

Evgeniya Leushina ◽

Timur Bulatov ◽

Elena Kozlova ◽

Ivan Panchenko ◽

Andrey Voropaev ◽

...

Keyword(s):

Organic Matter ◽

Lower Cretaceous ◽

Organic Matter Content ◽

Upper Jurassic ◽

Matter Content ◽

Source Rocks ◽

Organic Carbon Content ◽

Sea Level Changes ◽

The North ◽

Terrigenous Sedimentation

The present work is devoted to geochemical studies of the Bazhenov Formation in the north of the West Siberian Petroleum Basin. The object is the Upper Jurassic–Lower Cretaceous section, characterized by significant variations in total organic carbon content and petroleum generation potential of organic matter at the beginning of the oil window. The manuscript presents the integration of isotopic and geochemical analyses aimed at the evaluation of the genesis of the rocks in the peripheral part of the Bazhenov Sea and reconstruction of paleoenvironments that controlled the accumulation of organic matter in sediments, its composition and diagenetic alterations. According to the obtained data, the sediments were accumulated under marine conditions with a generally moderate and periodically increasing terrigenous influx. The variations in organic matter composition are determined by redox conditions and terrigenous input which correlate with the eustatic sea level changes during transgressive/regressive cycles and activation of currents. Transgression is associated with an intensive accumulation of organic matter under anoxic to euxinic conditions and insignificant influence of terrigenous sources, resulting in the formation of rocks with oil-generating properties. During the regression periods, the terrigenous sedimentation increased along with the dissolved oxygen concentration, and deposits with low organic matter content and gas-generating properties were formed.

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Dispersion of 226Ra in a Contaminated Environment

Radiation Protection Dosimetry ◽

10.1093/oxfordjournals.rpd.a080251 ◽

1988 ◽

Vol 24 (1-4) ◽

pp. 101-108 ◽

Cited By ~ 3

Author(s):

A.O. de Bettencourt ◽

M.M.G.R. Texeira ◽

M.J. Madruga ◽

M.C. Faisca (INVITED)

Keyword(s):

Organic Matter ◽

Vertical Distribution ◽

Gamma Spectrometry ◽

Laboratory Experiments ◽

Agricultural Soils ◽

Soil Characteristics ◽

Soil Samples ◽

Vertical Profiles ◽

Concentration Factors ◽

The Vertical Distribution

Abstract A radium salts extraction factory was established in Portugal in 1908 in the northeastern part of the country. It was abandoned in the forties and is now in ruins. Wastes (mainly sands) highly contaminated with 226Ra were left near these ruins. Measurements were performed to evaluate the extent of the contamination due to the dispersion of radium around this site, using portable Gieger tube equipment as well as by gamma spectrometry analyses of soil samples. Vertical profiles of soil were taken to a depth of about 40 cm, and 5 cm sections were analysed by gamma spectrometry to evaluate the vertical distribution of 226Ra and 210Pb. Some soil characteristics, such as pH, organic matter and exchangeable calcium and radium were also analysed. The dispersion of radium seems to be mostly due to the removal of contaminated wastes by mechanical means, although some leaching may have occurred. Laboratory experiments were also conducted on sandy and agricultural soils to study the leaching of 226Ra and 210Pb with rainwater and to help explain the results obtained in the field study. The observed influence of different parameters on this leaching are briefly discussed. Vegetables grown on these soils (mainly cabbage) were analysed for their content of 226Ra and 210Pb in order to calculate concentration factors. For 226Ra, these range from about 7 x 10-3 to 7 x 10-2. For 210Pb, they range from about 10-3 to 2 x 10-2.

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