Pore Structure and Permeability Characterization of High‐rank Coal Reservoirs: A Case of the Bide‐Santang Basin, Western Guizhou, South China

Guo, Chen; Qin, Yong; Ma, Dongmin; Xia, Yucheng; Bao, Yuan; Chen, Yue; Lu, Lingling

doi:10.1111/1755-6724.14295

Cited by 13 publications

(3 citation statements)

References 43 publications

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“…On the basis of the Hodot classification system, according to the relationship between the pore diameter and T 2 relaxation time in Equation ( 2), the pore-fracture structure can be classified according to the T 2 relaxation time [46][47][48][49] (micro-pore, <1 ms; transition pore, 1-10 ms; mesopore, 10-100 ms; macro-pore/micro-fracture, >100 ms). According to existing studies [50][51][52][53], mesopores, macro-pores and micro-fractures contribute to most of the porosity and provide the main space and paths for gas and water flow. It is not difficult to see from Figure 4 that the T 2 spectra of each granite sample can be roughly divided into left and right peaks with T 2 = 10 ms as the dividing line.…”

Section: Triaxial Compression Testmentioning

confidence: 99%

Permeability and Mechanical Response of Granite after Thermal and CO2 Bearing Fluid Hydro-Chemical Stimulation

et al. 2022

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The large scale extraction of geothermal energy can reduce CO2 emissions. For hot dry rocks, the key to successful utilization depends on the efficiency of reservoir reconstruction. The chemical and thermal stimulation methods are always used in geothermal reservoir reconstruction except in hydraulic fracturing with high fluid injection pressure, which is believed to reduce the seismic hazard by applying before the high-pressure hydraulic fracturing stimulation. However, at the laboratory scale, there are still very limited experimental studies illustrating the combined effects of chemical and thermal stimulation on the permeability and mechanical properties of granite, which is regarded as the main type of hot dry rock. In this paper, comparative stimulation experiments were carried out, including thermal/cold stimulation, CO2 bearing solution hydro-chemical stimulation, combined thermal and CO2 bearing fluid stimulation. By means of nuclear magnetic resonance analysis, permeability test and triaxial compression test, the changes of the micro-structure, permeability and mechanical properties of granite under various stimulation conditions were analyzed. The experimental results show that, compared with the single thermal stimulation and CO2 bearing fluid hydro-chemical stimulation, the superposition effect of thermal and CO2 bearing fluid hydro-chemical stimulation can increase the number of micro-fractures in granite more effectively, thus increasing the permeability, while the elastic modulus and compressive strength decrease. Moreover, the cooling mode on the granite also has a certain influence on the stimulation effect. After water-cooling on the heated granite (300 °C), combined with the CO2 bearing fluid stimulation (240 °C, 20 MPa), the permeability of granite is the highest, increasing by 17 times that of the initial state, and the porosity also increases by 144.4%, while the elastic modulus and compressive strength decrease by 14.3% and 18.4%, respectively. This implies that the deterioration of mechanical properties due to the micro-fractures increased by the thermal and chemical stimulation can enhance the fluid conductivity and heat extraction of granite. The methods in this paper can provide a reference for the combined application of thermal and chemical stimulation technology in artificial reservoir reconstruction of hot dry rocks.

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Section: Triaxial Compression Testmentioning

confidence: 99%

Permeability and Mechanical Response of Granite after Thermal and CO2 Bearing Fluid Hydro-Chemical Stimulation

et al. 2022

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“…Distinctively, the regional coal measure superposed reservoirs exhibit a unique composition, featuring coal seams interbedded with sandstones and mudstones, which markedly deviate from the coal measure superposed reservoirs identified in North China and Northeast China. , The exploration and development of coal measure gas include coal measure gas resource evaluation and favorable area selection, geological surveying within target zones, and coal measure gas development (well drilling and completion, reservoir enhancement and renovation, and integrated layer drainage and extraction). The research efforts pertinent to Guizhou’s coal measure gas exploration and development have predominantly focused on aspects such as coal measure gas resource evaluation and geological selection within the block, − reservoir characteristics and geochemical characteristics of coal measure gas well water, − coal measure gas development process models, and production control factors associated with coal measure gas wells. ,− However, the current rock mechanics and damage characterization for the varied lithologies found within Guizhou’s coal measures, as well as the establishment of a comprehensive evaluation system for coal measure rock masses, remain markedly inadequate, which is extremely mismatched with the development of coal measure gas in the region and is in urgent need of research and enrichment.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Rock Mechanical Characteristics and Establishment of an Evaluation System for Coal Measures in the Longtan Formation, Guizhou Province

Liang,

Cao,

Sang

et al. 2024

ACS Omega

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The mechanical properties of coal measure rocks and their evaluation significantly impact the process and efficacy of coal measure exploration and development. This study focuses on the Guizhou Longtan Formation coal measure. The mechanical and fracturing characteristics of coal measure rock samples are analyzed via well coring, geophysical logging, and indoor experiments. Additionally, predictive models for rock mechanical parameters are developed, and an evaluation system for the Longtan Formation coal measure rock mass is established. The findings are as follows: (1) Coal measure rocks in Guizhou's Longtan Formation exhibit a relatively low elastic modulus and tensile strength, but a substantial variation in compressive strength. The triaxial compressive strength, elastic modulus, and residual strength increase nonlinearly with increasing confining pressure. As the confining pressure increases, the failure mode of the mudstone and siltstone transitions from primarily splitting failure to shearing failure. (2) Strong correlations are calculated between logging parameters and rock mechanical parameters and are used to construct three regression prediction models, yielding an average prediction accuracy of approximately 85% for rock mechanical properties. (3) Considering the rock mechanical properties, rock mass structure and stratigraphic characteristics, and the occurrence environment related to the characteristics of rock mass affecting coal measure gas development, eight evaluation indices are selected. The analytic hierarchy process−entropy weighting method is used to determine the weights of the comprehensive evaluation indices, and a coal measure rock mass evaluation system is established by utilizing gray clustering analysis. The evaluation results categorize the mudstone group (mudstone and silty mudstone) as Classes III−IV, the fine sandstone group as Classes I and II, and the siltstone group (muddy siltstone and siltstone) as Classes II and III. A comparative analysis with fuzzy comprehensive evaluation results and extenics theory evaluation results demonstrated a high level of consistency. These findings benefit coal measure rock mechanics classification and quantitative research on rock mechanics properties, providing a solid foundation for efficient coal measure gas exploration and development.

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“…In addition to the above technologies, nuclear magnetic resonance technology can be used to test the percolation characteristics of pore structures. Guo et al [42] studied the pore characteristic parameters of coal-bearing formations based on nuclear magnetic resonance technology, analyzed the main rock formations in the region, and characterized the connection between pores and throats. Li et al [43] used nuclear magnetic resonance and mercury intrusion technology to study the relationship between the pore size distribution in coal-bearing formations and the pressure applied by the tests.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Simulations of Pore Structures and Seepage Characteristics of Deep Sandstones

Zhu,

Wu,

Zhang

et al. 2023

Processes

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Previously conducted studies have established that deep underground rock masses have complex pore structures and face complex geological conditions. Therefore, the seepage problem of such rock masses seriously affects engineering safety. To better explore the seepage law of deep rock masses and ensure engineering safety, indoor experimental methods such as casting thin sections, scanning electron microscopy, and mercury intrusion testing were utilized in this study. The microscopic pore shape, size, distribution, and other structural characteristics of sandstone in coal bearing strata were analyzed. The tortuosity calculation formula was obtained by the theoretical derivation method. And a numerical model was established for seepage numerical simulation research through microscopic digital image methods. The seepage law of surrounding rocks in the Tangkou Coal Mine roadway under different conditions is discussed. The research results indicate that the complexity of the pore structure in porous media leads to an uneven distribution of flow velocity and pressure within the medium. Meanwhile, with the change of physical properties, the fluid flow characteristics also undergo significant changes. The research results can effectively guide micropore water blocking, reduce the impact of groundwater on the environment, ensure the environment and safety of the project, and provide guidance for other geological projects.

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Pore Structure and Permeability Characterization of High‐rank Coal Reservoirs: A Case of the Bide‐Santang Basin, Western Guizhou, South China

Cited by 13 publications

References 43 publications

Permeability and Mechanical Response of Granite after Thermal and CO2 Bearing Fluid Hydro-Chemical Stimulation

Permeability and Mechanical Response of Granite after Thermal and CO2 Bearing Fluid Hydro-Chemical Stimulation

Analysis of Rock Mechanical Characteristics and Establishment of an Evaluation System for Coal Measures in the Longtan Formation, Guizhou Province

Experimental and Numerical Simulations of Pore Structures and Seepage Characteristics of Deep Sandstones

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