The effects of organic carbon content and thermal maturity on acoustic parameters in a black shale: Woodford Shale, Permian Basin, West Texas

Geophysics ◽  
2019 ◽  
Vol 84 (6) ◽  
pp. D231-D248 ◽  
Author(s):  
Nicholas B. Harris ◽  
Al Moghadam ◽  
Tian Dong
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Physical Properties ◽  
P Wave ◽  
Thermal Maturity ◽  
S Wave ◽  
Permian Basin ◽  
Woodford Shale ◽  
Load Bearing ◽  
Core Samples

We have derived relationships between organic carbon and acoustic properties in the Woodford Shale, an Upper Devonian organic-rich shale in the Permian Basin, Texas. Extensive core data enable us to relate measured total organic carbon (TOC) on core samples to gamma log response; in turn, gamma log-calculated TOC is compared with P-wave [Formula: see text] and S-wave [Formula: see text] velocities, density, and derivative properties including [Formula: see text], Young’s modulus, Poisson’s ratio, [Formula: see text], and [Formula: see text]. Because we sampled two wells at very different thermal maturity (early oil window and wet gas window), we can examine the effect of thermal maturity on these parameters. In both wells, [Formula: see text] and [Formula: see text] decrease with increasing TOC, exhibiting a rapid decrease from 0% to approximately 1.5% TOC, and a slower decrease above 1.5% TOC, similar to results from ultrasonic experiments on core samples, that we attribute to a shift from a mineral grain load-bearing to an organic matter load-bearing fabric. The [Formula: see text] decreases by 28% and [Formula: see text] by 20% over the range of 0.5%–12% TOC. [Formula: see text] and [Formula: see text] correlate more strongly to neutron porosity than to TOC in the less mature well, related to the development of a bitumen phase that is relatively soft and less dense and has greater impact on rock physical properties than kerogen; this effect disappears in the high-maturity well in which bitumen was further cracked to petroleum and physical properties of bitumen changed with increased aromatization. The effect of increased thermal maturity is to increase [Formula: see text] by approximately 12%, [Formula: see text] by 25%, and P-wave impedance by 12%. [Formula: see text] ratios decrease with increasing TOC, contrary to the behavior expected for the incorporation of a soft material into a rock. We suggest that the rock develops a horizontal planar fabric at lower TOC values that absorbs S-wave energy, counteracting the effect of the organic matter.

Modelling dynamic interactions between soil structure and soil organic matter

2020 ◽  
Author(s):  
Nicholas Jarvis ◽  
Elsa Coucheney ◽  
Claire Chenu ◽  
Anke Herrmann ◽  
Thomas Keller ◽  
...  
Keyword(s):  
Organic Matter ◽  
Carbon Sequestration ◽  
Soil Organic Matter ◽  
Organic Carbon ◽  
Physical Properties ◽  
Management Practices ◽  
Animal Manure ◽  
Soil Bulk Density ◽  
Organic Carbon Content

<p>The aggregated structure of soil is known to reduce rates of soil organic matter (SOM) decomposition and therefore influence the potential for long-term carbon sequestration. In turn, the storage and turnover of SOM strongly determines soil aggregation and thus the physical properties of soil. The two-way nature of these interactions has not yet been explicitly considered in soil organic matter models. In this study, we present and describe a new model of these dynamic feedbacks between SOM storage, soil pore structure and soil physical properties. We show the results of a test of the model against measurements made during 61 years in a field trial located near Uppsala (Sweden) in two treatments with different OM inputs (bare fallow, animal manure). The model was able to successfully reproduce long-term trends in soil bulk density and organic carbon content (SOC), as well as match limited data on soil pore size distribution and surface elevation. The results suggest that the model approach presented here could prove useful in analyses of the effects of soil and crop management practices and climate change on the long-term potential for soil organic carbon sequestration.</p>

Freeze-thaw dynamics in synthetic permafrost soil columns with variable organic carbon content

2020 ◽  
Author(s):  
Jelte de Bruin ◽  
Victor Bense ◽  
Martine van der Ploeg
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Physical Properties ◽  
Groundwater Flow ◽  
Soil Column ◽  
Soil Physical Properties ◽  
Soil Columns ◽  
Cold Regions ◽  
Warming Climate ◽  
Permafrost Thawing

<p>Cold-regions hold a pool of organic carbon that has accumulated over many thousands to millions of years and which is currently kept immobile by permafrost. However, in a warming climate, a deepening of the active layer results in the release of greenhouse gasses CO<sub>2</sub> and CH<sub>4</sub> into the atmosphere from this carbon pool. Additionally, due to the degradation of deeper permafost, soil hydraulic properties and associated groundwater flow paths are shifting rapidly as a result of which also organic carbon in deeper permafrost is being dissolved into groundwater, which can then reach the surface environment via groundwater flow.  This provides an additional mechanism by which permafrost carbon can be mobilized in  a warming climate, and one which is likely increasingly important for progressive surface warming.</p><p>Although the process of carbon leaching from thawing organic rich permafrost layers into the groundwater is an increasingly important part of the carbon cycle of cold-regions, it is notoriously difficult to measure in situ or incorporate into numerical model assessments due to the highly heterogeneous properties of the permafrost, and lack of process knowledge. In particular, the crucial understanding of the influence of different soil physical properties such as soil grain size and organic matter content on permafrost thawing processes is missing, as well the precise release mechanisms  of organic matter into pore waters in thawing soils.</p><p>This study employs lab soil column experiments to investigate the interplay between soil physical properties and thawing dynamics of permafrost. One meter high soil columns are frozen to create controlled permafrost conditions. A range of sand grain sizes (0.1 to 0.8mm) and organic matter contents (1 to 10 wt%) representative for sedimentary permafrost are used. The column is thermally insulated on the sides and top, exposing only one face to ambient temperature in the climate chamber. In this way one-dimensional heat flow conditions are created. So far, the columns are equipped with arrays of temperature sensors. Experiments consist of a cycle of freezing and thawing. Our initial data and analysis illustrate how a fast evolving thawing front develops through the frozen soil column  including the effects of latent heat at the thawing front. Numerical modeling allows to infer the soil thermal properties relevant to model the permafrost thawing process.</p>

scholarly journals ASPECTOS FITOSSOCIOLÓGICOS E INDICADORES DA QUALIDADE DO SOLO EM SISTEMAS AGROFLORESTAIS

Nativa ◽  
2018 ◽  
Vol 6 ◽  
pp. 745 ◽  
Author(s):  
Lucas Henrique Vieira Lenci ◽  
Emanuel Fernando Maia de Souza ◽  
Adriano Reis Prazeres Mascarenhas ◽  
Antonio De Arruda Tsukamoto Filho ◽  
Gilderlon Dos Santos Soares
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Pearson Correlation ◽  
Agroforestry Systems ◽  
Carbon Stocks ◽  
Soil Core ◽  
Sustainable Rural Development ◽  
Undisturbed Soil ◽  
Core Samples ◽  
Physical Attributes

Objetivou-se avaliar os atributos florísticos e fitossociológicos, os atributos físicos do solo e os estoques de matéria orgânica e carbono orgânico do solo de cinco sistemas agroflorestais (SAFs) da Região Central de Rondônia. Para isso, realizou-se o levantamento florístico para determinação da área basal, riqueza, diversidade e uniformidade das espécies. No processo de amostragem do solo, dividiu-se cada um dos sistemas em quatro quadrantes e coletou-se amostras indeformadas nas profundidades de 0cm a 20cm e 20cm a 40cm para determinação da densidade do solo, macroporosidade, microporosidade e porosidade total; e amostras deformadas nas profundidades de 0cm a 5cm, 5cm a 10cm, 10cm a 20cm e 20cm a 40cm para determinação dos estoques de matéria orgânica e carbono orgânico do solo. Os resultados foram submetidos à correlação de Pearson para verificar interações entre os parâmetros avaliados. Os atributos florísticos e fitossociológicos variaram consideravelmente entre os sistemas agroflorestais e, de modo geral, os diferentes arranjos de SAFs apresentaram atributos físicos próximos ou abaixo dos valores considerados críticos para crescimento radicular. Além disso, notou-se que os SAFs mais adensados e com estrutura do solo favorável ao desenvolvimento das plantas favoreceram maiores quantidades de matéria orgânica e carbono orgânico do solo.Palavras-chave: agroecossistemas, física do solo, estoque de carbono, desenvolvimento rural sustentável. PHYTOSOCIOLOGICAL ASPECTS AND SOIL QUALITY INDICATORS IN AGROFORESTRY SYSTEMS ABSTRACT:This study aimed to analyze floristic and phytosociological attributes, soil physical attributes, and organic matter and soil organic carbon stocks in five agroforestry systems (AFS) in the Central Region of Rondônia. Floristic surveys were carried out to determine basal area, richness, diversity and uniformity of the species. In the soil sampling process, each of the systems were divided into four quadrants, and undisturbed soil core samples were collected at 0-20 and 20-40 cm depths to determine soil bulk density, macroporosity, microporosity and total porosity; disturbed soil core samples were collected at 0-5, 5-10, 10-20 and 20-40 cm depths to determine soil organic matter and carbon organic stocks. Pearson correlation was applied to evaluate significant interactions among the results. Floristic and phytosociological attributes varied considerably between agroforestry systems. In general, the agroecosystems showed soil physical attributes close to or below the values considered critical for root growth. Favorable soil structure and denser arrangements resulted in higher amounts of organic matter and organic carbon in the soil.Keywords: agroecosystems, soil physics, carbon stocks, sustainable rural development.

Study on Volcanic Rock Chemical Composition and Physical Properties in Hainan Province

2013 ◽  
Vol 405-408 ◽  
pp. 1844-1851
Author(s):  
Yong Sheng Yao ◽  
Jian Long Zheng ◽  
Bo Ming Tang ◽  
Hong Zhou Zhu
Keyword(s):  
Chemical Composition ◽  
Physical Properties ◽  
Volcanic Rock ◽  
Wave Velocity ◽  
Volcanic Rocks ◽  
P Wave ◽  
Hainan Province ◽  
S Wave ◽  
X Ray ◽  
P Wave Velocity

In order to study the chemical composition of volcanic rock and physical properties in Hainan province, used the method of X-ray fluorescence, analysises on its chemical composition, and researched the physical properties of volcanic rocks including density test, porosity test, acoustic test, resistance test. The results showed that: the volcanic rock is tholeiitic at the cavity of lava area in Hainan province, P-wave velocity and S-wave velocity would change with the changing of porosity.

Micro-Pore Reservoir Spaces and Gas-Bearing Characteristics of the Shale Reservoirs of the Coal Measure Strata in the Qinshui Basin

2021 ◽  
Vol 21 (1) ◽  
pp. 371-381
Author(s):  
Ruying Ma ◽  
Meng Wang ◽  
Weidong Xie ◽  
Haichao Wang
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Physical Properties ◽  
Specific Surface ◽  
Pore Volume ◽  
Gas Content ◽  
Positive Correlation ◽  
Specific Pore Volume ◽  
Shale Reservoirs ◽  
Gas Bearing

To study the exploration potential of the Carboniferous-Permian transitional shale reservoirs in the Qinshui Basin, the Y5 well was selected as the research object, and experiments including organic geochemical tests, microscopic observations, scanning electron microscopy, X-ray diffraction analysis, high-pressure mercury intrusion, methane isothermal adsorption, and low-temperature nitrogen adsorption were carried out to analyse the physical properties of the shale reservoirs of interest. The results show that (1) The organic matter type of the samples is type III, the total organic carbon contents range from 0.27% to 20.52% (avg. 3.15%), the RO values are between 2.45% and 3.36% (avg. 2.86%), and the Tmax values range from 311.00 °C to 575.20 °C (avg. 493.31 °C). These results indicate that the organic matter in the study area is abundant and has experienced a high degree of thermal evolution. (2) The brittleness index is low (avg. 43.81%), and the shale pores in the study area are well developed. The pores contain organic matter-hosted pores, intraparticle pores, interparticle pores, and micro-cracks. (3) The methane isotherm adsorption average contents of the two samples are 0.2968 m3/t and 1.0824 m3/t, and the average contents of the on-site desorbed gas content and measured total gas content are 0.55889 m3/t and 0.8624 m3/t, respectively. (4) The kaolinite and illite contents have a significant negative effect on the specific surface area of the macro-pores and the specific pore volume of the meso-pores. The illite content is conducive to the development of the pore diameter and specific surface area of the meso-pores, and the quartz content has a positive correlation with the specific pore volume of the macro-pores. (5) The measured total gas content has a significant positive correlation with the total organic carbon and a weak positive correlation with the contents of quartz and illite, and the desorbed gas content shows the same correlations. This study demonstrates the physical properties, microscopic pore characteristics, and gas-bearing characteristics of shale reservoirs and their influencing factors in detail.

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