In-situ stress, pore pressure and stress-dependent permeability in the Southern Qinshui Basin

Meng, Zhaoping; Zhang, Jincai; Wang, Rui

doi:10.1016/j.ijrmms.2010.10.003

Cited by 254 publications

(110 citation statements)

References 27 publications

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“…For fractured media (including coal), Meng et al (2011) and Zhang et al (2007) proposed that permeability strongly depends on the fracture volume or fracture aperture. Commonly used Kozeny-Carman equation can be adopted to describe permeability and porosity relationship in porous media Carman (1956):…”

Section: Permeability and Pore Volume Relationship And Possible Applimentioning

confidence: 99%

Nanoscale Pores in Coal Related to Coal Rank and Deformation Structures

et al. 2015

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Experimental results show that nanoscale pores in coal are affected by coal rank and deformation structures. In terms of pore volume, the transitional pores occupy the largest proportion, and in terms of specific surface area, the sub-micropores take up the largest proportion. For weak brittle deformed coal (including normal structured coal), when the coal rank increases, the volume and specific surface area of pores in different sizes firstly decrease and then increase. The volume and specific surface area of transitional pores and micropores in coal reach the minimum at about R O,ran = 2.0 %. After that, a slow increasing trend is observed. The volume of sub-micropores reaches the minimum at about R O,ran = 1.5 % and then shows a trend of rapid growth as coal rank increases. As the degree of coal deformation increases, both pore volume and specific surface area have a significant increase. Under strong tectonic deformation, both the volume and total specific surface area of the nanoscale pores and of sub-micropores increase significantly; the volume of transitional pores increases moderately, and their specific surface area shows a decreasing trend; the volume and specific surface area increments of micropores decline rapidly as the degree of metamorphism increases.

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Section: Permeability and Pore Volume Relationship And Possible Applimentioning

confidence: 99%

Nanoscale Pores in Coal Related to Coal Rank and Deformation Structures

et al. 2015

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“…The change in permeability properties will also influence the stress state (Meng et al 2011;Jasinge et al 2011). Therefore, the relationship between coal matrix and fluid (like gas) is interactive and mutually constrained.…”

Section: Concepts and Basic Theoriesmentioning

confidence: 99%

Coal permeability model on the effect of gas extraction within effective influence zone

Xie

Gao

et al. 2015

Geomech. Geophys. Geo-energ. Geo-resour.

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In situ gas extraction is the main measure adopted by mines to achieve mining safety standards. Coal permeability is significantly influenced by coal shrinkage during gas release. Based on effective stress and additional damage that resulted from gas extraction, a unique model was proposed to describe the spatial and temporal distribution of coal permeability within the effective influence zone. Calculation models for the conditions of one and two extracting boreholes were developed. A parametric study on both two models was also conducted, in which the effect of extraction time, extraction pressure, interval between two boreholes, and extraction pressure combination were qualitatively analyzed. The results demonstrated that with the increase of extraction time, gas extraction can result in less permeability reduction in the beginning but can enhance permeability. Coal permeability obviously increases when extraction time increases but gradually stabilizes, presenting ''high middle and low around'' surrounding the extracting borehole. Meanwhile, a decreasing relative amplification implies that permeability ratio does not increase linearly with the increase in extraction pressure. Both intervals between two extracting boreholes and different combinations of extraction pressure significantly influence the distribution of coal permeability. A comparison with some previous permeability studies was conducted to validate the proposed model, and the predicted evolution results matched the permeability testing data. In conclusion, the proposed model is consistent with the phenomenon in real engineering, and the model results can provide preliminary guidance for the design of extracting borehole distribution.

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“…The in situ stress includes three mutually orthogonal principal stresses in the subsurface (e.g., Meng et al 2011), i.e., the vertical (overburden) stress (r V ), the maximum horizontal and minimum horizontal stresses (r H , r h ). In situ stress is normally measured from borehole mini-frac or hydraulic fracturing tests (e.g., Haimson and Fairhurst 1967).…”

Section: Underground Measurements Of In Situ Stress and Miming-inducementioning

confidence: 99%

A study of mine water inrushes by measurements of in situ stress and rock failures

2015

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This paper presents underground measurements (e.g., mini-frac tests) for in situ stress, hydraulic fractures, strata failures and hydraulic conductivity enhancement induced by coal extraction to study mechanisms of coal mine water inrushes. Mining perturbs the original state of in situ stress and results in stress redistribution. This causes rock failures and creates a water-conducting failure zone around a mining panel. If a confined aquifer is situated in the coal seam floor, the mining-induced stresses near the aquifer also generate hydraulic fractures in the rocks near to the aquifer. The mining-induced water-conducting failures and hydraulic fractures by the water pressure of the aquifer are the major reasons to cause water inrushes. The mining-induced water-conducting zone is obtained from theoretical studies and field measurements. The generating condition of the hydraulic fractures by the water pressure is also studied. Methods for predicting water inrushes are given based on the study of water inrush mechanisms. The mechanisms of water inrushes induced by faults are also analyzed from the case studies of water inrushes. It is of crucial importance to detect and map faults, paleo-sinkhole and other geological structures before mining. New mining methods are proposed for mining near confined aquifers to reduce the risks of water inrushes.

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In-situ stress, pore pressure and stress-dependent permeability in the Southern Qinshui Basin

Cited by 254 publications

References 27 publications

Nanoscale Pores in Coal Related to Coal Rank and Deformation Structures

Nanoscale Pores in Coal Related to Coal Rank and Deformation Structures

Coal permeability model on the effect of gas extraction within effective influence zone

A study of mine water inrushes by measurements of in situ stress and rock failures

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