A rock physics model for characterizing the total porosity and velocity of shale: A case study in Fuling area, China

Xu, Zhuang; Shi, Wanzhong; Zhai, Gangyi; Clay, Campbell; Zhang, Xiaoming; Peng, Nyujia

doi:10.1016/j.marpetgeo.2018.10.010

Cited by 18 publications

(8 citation statements)

References 25 publications

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“…One category is the examination of images through processes such as two-dimensional (2D) image processing [14][15][16] and three-dimensional (3D) image reconstruction [17]. The other category is theoretical calculation, including low-field NMR [18,19], rock physics models [20,21], and calculations based on the mass balance principle [3,7,12,13,22]. However, the contributions of organic pores to total porosity vary significantly, and there is, thus, much discussion of the controlling factors of organic porosity and total porosity [14,[23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Total Organic Carbon Enrichment and Its Impact on Pore Characteristics: A Case Study from the Niutitang Formation Shales in Northern Guizhou

Liu

Tang

2019

Energies

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This study analyzes samples from the Lower Cambrian Niutitang Formation in northern Guizhou Province to enable a better understanding of total organic carbon (TOC) enrichment and its impact on the pore characteristics of over-mature marine shale. Organic geochemical analysis, X-ray diffraction, scanning electron microscopy, helium porosity, and low-temperature nitrogen adsorption experiments were conducted on shale samples. Their original TOC (TOCo) content and organic porosity were estimated by theoretical calculation, and fractal dimension D was computed with the fractal Frenkel–Halsey–Hill model. The results were then used to consider which factors control TOC enrichment and pore characteristics. The samples are shown to be dominated by type-I kerogen with a TOC content of 0.29‒9.36% and an equivalent vitrinite reflectance value of 1.72‒2.72%. The TOCo content varies between 0.64% and 18.17%, and the overall recovery coefficient for the Niutitang Formation was 2.16. Total porosity of the samples ranged between 0.36% and 6.93%. TOC content directly controls porosity when TOC content lies in the range 1.0% to 6.0%. For samples with TOC < 1.0% and TOC > 6.0%, inorganic pores are the main contributors to porosity. Additionally, pore structure parameters show no obvious trends with TOC, quartz, and clay mineral content. The fractal dimension D1 is between 2.619 and 2.716, and D2 is between 2.680 and 2.854, illustrating significant pore surface roughness and structural heterogeneity. No single constituent had a dominant effect on the fractal characteristics.

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Section: Introductionmentioning

confidence: 99%

Total Organic Carbon Enrichment and Its Impact on Pore Characteristics: A Case Study from the Niutitang Formation Shales in Northern Guizhou

Liu

Tang

2019

Energies

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“…The higher the content of quartz, the better the fracturing ability of shale. Further research shows that there is a high positive correlation between siliceous minerals and TOC content in the high-quality shale of the Wufeng-Longmaxi formation, that is, the higher the content of siliceous minerals, the higher the content of organic carbon (Yang et al, 2016;Dong et al, 2019;Khan et al, 2019); at the same time, it is found that the content of siliceous minerals is positively correlated with the gas and porosity of shale (Yang et al, 2016;Dong et al, 2019;Xu et al, 2019), suggesting that siliceous minerals are of great significance for the generation and exploration of shale gas in this area. Therefore, it is very important to clarify the origin of quartz for reservoir brittleness evaluation, gas bearing evaluation, and development potential evaluation of shale (Dong and Harris, 2020;Qiu et al, 2020).…”

Section: Introductionmentioning

confidence: 92%

The Origin of Silica of Marine Shale in the Upper Ordovician Wulalike Formation, Northwestern Ordos Basin, North China

Zhang

Huang

et al. 2021

Front. Earth Sci.

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The shale of the Wulalike Formation developed in the northwestern Ordos Basin is considered to be an effective marine hydrocarbon source rock. One of the key factors for successful shale gas exploration in the Wufeng–Longmaxi Formation in the Sichuan Basin is the high content of biogenic silica. However, few people have studied the siliceous origin of the Wulalike shale. In this study, we used petrographic observation and element geochemistry to analyze the origin of silica in the Wulalike shale. The results show that the siliceous minerals are not affected by hydrothermal silica and mainly consist of biogenic and detrital silica. A large number of siliceous organisms, such as sponge spicules, radiolarians, and algae, are found under the microscope. It has been demonstrated that total organic carbon has a positive correlation with biogenic silica and a negative correlation with detrital silica, and biogenic silica is one of the effective indicators of paleoproductivity. Therefore, the enrichment of organic matter may be related to paleoproductivity. Through the calculation of element logging data in well A, it is found that biogenic silica is mainly distributed in the bottom of the Wulalike Formation, and the content of biogenic silica decreases, while the content of detrital silica increases upward of the Wulalike Formation. Biogenic silica mainly exists in the form of microcrystalline quartz, which can form an interconnected rigid framework to improve the hardness and brittleness of shale. Meanwhile, biogenic microcrystalline quartz can protect organic pores from mechanical compaction. Therefore, it may be easier to fracture the shale gas at the bottom of the Wulalike Formation in well A.

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“…where V PÀwave denotes the velocity of P-wave. In addition, there exists a relation between the P-wave velocity and S-wave velocity, 35 which can be written as…”

Section: Deformation Modulus and Thermal Conductivitymentioning

confidence: 99%

Thermophysical–mechanical properties evaluations of porous geomaterials by CT images and digital–virtual modeling

Zhao,

Berto,

Zou

et al. 2024

Fatigue Fract Eng Mat Struct

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In this work, the color difference phase separation (CDPS) approach is proposed to segment the solid and pore phases. Pore‐scale variables are defined to describe the microstructural characteristics. Novel relations to quickly determine the deformation moduli and thermal conductivity are established. Digital–virtual modeling to investigate the mechanical and thermal properties is addressed. The correlation between pore‐scale variables and the mechanical and thermal properties is investigated. Results show that the calculated shear and Young's moduli decrease and the computed Poisson's ratio increases as porosity increases. The deformation moduli and thermal conductivity increase with increasing pore radius for different types of rocks. Excellent consistencies are found between the digital–virtual and realistic experimental results. The proposed method provides useful tools to fast and accurately determine the deformation moduli and thermal conductivity, which is helpful for the underground space and deep energy resource explorations.

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A rock physics model for characterizing the total porosity and velocity of shale: A case study in Fuling area, China

Cited by 18 publications

References 25 publications

Total Organic Carbon Enrichment and Its Impact on Pore Characteristics: A Case Study from the Niutitang Formation Shales in Northern Guizhou

Total Organic Carbon Enrichment and Its Impact on Pore Characteristics: A Case Study from the Niutitang Formation Shales in Northern Guizhou

The Origin of Silica of Marine Shale in the Upper Ordovician Wulalike Formation, Northwestern Ordos Basin, North China

Thermophysical–mechanical properties evaluations of porous geomaterials by CT images and digital–virtual modeling

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