Effects of geological pressure and temperature on permeability behaviors of middle-low volatile bituminous coals in eastern Ordos Basin, China

Wu, Shuang; Tang, Dazhen; Li, Song; Wu, Haiyong; Xiong, Hu; Zhu, Xueguang

doi:10.1016/j.petrol.2017.03.034

Cited by 41 publications

(18 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Feng et al found that gas permeability of anthracite decreased at first then increased and finally decreased again with temperature increasing [26]. Wu et al found that the increased temperature can induce a series of results, such as promoting gas desorption, enhancing gas slippage effect, and inducing coal matrix thermal swelling, resulting in decomposition [27]. And all of those can affect the gas permeability of coal further.…”

Section: Introductionmentioning

confidence: 99%

Variable Pore Structure and Gas Permeability of Coal Cores after Microwave Irradiation

et al. 2018

View full text Add to dashboard Cite

The experimental work in this paper investigated the effect of microwave energy on pore structure and gas permeability of coal cores. Fifteen coal samples were irradiated under the condition of 2.45 GHz with 6 kW. The effect of microwave irradiation on the pore structure of coal samples was evaluated by nuclear magnetic resonance (NMR). The water saturation degree has little influence on transverse relaxation time (T2) distribution before the microwave treatment. By contrast, water saturation degree obviously affects the T2 distribution after the microwave energy treatment. Coal permeability increased after microwave energy treatment. But fractal dimension decreased after microwave energy treatment. The results show that microwave energy has a potential for degassing coal seams.

show abstract

Section: Introductionmentioning

confidence: 99%

Variable Pore Structure and Gas Permeability of Coal Cores after Microwave Irradiation

et al. 2018

View full text Add to dashboard Cite

show abstract

“…Under the thrust or nappe action of peripheral faults into the basin, the basin is uplifted as a whole, and low angle or interlayer sliding occurs, forming slip thrust fault, which releases the energy accumulated by orogeny movements around the basin, and the strata are not deformed obviously (Li et al, 2014;Wu et al, 2017;Xiao et al, 2020). However, most of the basement faults have been activated, and the deep fractures have obvious control on the shallow ones.…”

Section: Comparison Of In-situ Stress Test Results In Burtai Minementioning

confidence: 99%

In-Situ Stress Measurements and Stress Accumulation Level Analysis of Coal Mines in Northern Ordos Basin

Yang¹,

Ning²,

Li³

et al. 2020

Preprint

View full text Add to dashboard Cite

For non-directional drilling cores, the sample selection and test method for Kaiser effect (KE) in-situ stress measurement were proposed, and the magnitude and direction of its principal stresses were theoretically derived. Based on this method, the KE of 423 samples in Burtai and Baode coal mines in northern Ordos Basin (NOB) were tested. The results show that σH, σh and σv vary with depth and location, and their values increase with increasing of depths. Generally, horizontal stresses play a leading role. There are main stress regimes in NOB: σH > σh > σv (Burtai, <172m; Baode, <170m) and σH > σv > σh (Burtai, 170-800 m; Baode, 170-400 m), and the σv > σH > σh stress regime is mainly distributed in moderately deep to deep coal mines. For rock masses with a depth of 350m, k ((σH + σh) / 2σv) tends to 1, indicating that deep critical state will gradually emerge. The test results were compared with those of overcoring method (OC), elastic strain recovery (ASR) and micro-hydraulic fracturing (HF). The relative errors of σH, σh and σv are 14.90%, 19.67%, 15.47% (Burtai) and 10.74%, 22.76%, 19.97% (Baode), and they are all within a reasonable range required by the project, which verifies the reliability of KE method. The dominant orientation of σH (Burtai, NE-NNE; Baode, NEE) was obtained by using paleomagnetic technology, which is consistent with that (NE-NEE) of earthquake focal mechanisms in this area. Based on Byerlee-Anderson theory, the stress accumulation level of mine rock mass was discussed. Under dry rocks or hydrostatic pressure rocks, the friction coefficient of faults is both low, which is less than the lower limit (0.6) of strike-slip faults slip, indicating that the fracture stress with a low level around the study area is lower than the friction limit stress. The stress accumulation level in Baode mine is slightly larger than that in Burtai mine.

show abstract

“…The stress sensitivity of permeability can be quantitatively represented by the compressibility of the coal reservoir, which is the change rate of permeability under a change in unit effective stress relative to initial permeability and can be calculated by formula (7) proposed by Seidle et al. (1992) and Wu et al. (2017) …”

Section: Resultsmentioning

confidence: 99%

“…The external fluid can damage a reservoir in many ways, but this study mainly discusses the effects of acid sensitivity, alkalinity, and salt sensitivity on reservoir stress sensitivity. Few scholars have studied this aspect and only a few have analyzed the influence of water saturation and temperature on reservoir stress sensitivity (Meng et al., 2015; Wu et al., 2017). Previous research on the stress sensitivity of coal reservoirs has mostly concentrated on middle and high coal ranks, and stress sensitivity analyses of low-rank coal, particularly lignite, are lacking (Yang et al., 2011).…”

Section: Introductionmentioning

confidence: 99%

Study on stress sensitivity of lignite reservoir under salinity and pH composite system

Wang

Qin

Shen

et al. 2017

Energy Exploration & Exploitation

View full text Add to dashboard Cite

The stress sensitivity of a coal reservoir is an important factor affecting the productivity of the coalbed methane well. Determining methods to reduce the stress sensitivity of coal reservoirs in the process of coalbed methane well drainage and recovery is of significance for the efficient development of coalbed methane. Based on a multiindex comprehensive evaluation of the stress sensitivity of a lignite reservoir under different pH and salinity, a permeability prediction model and productivity model of the coalbed methane well are established in consideration of the stress sensitivity under the influence of pH and salinity. Analysis is conducted on changes in permeability with effective stress and the mechanism involved in the stress-sensitive effect in a lignite reservoir under these two influencing factors. Results show that the relation between dimensionless permeability and effective stress is in good agreement with a negative exponential relationship. In addition, the relation between the stress-sensitive coefficient and effective stress can be divided into a fluctuation stage and a stabilization stage using 15-17 MPa as the boundary. It is also apparent that an increase in salinity is beneficial for decreasing the stress sensitivity of a reservoir under alkaline conditions, but this effect gradually decreases with an increase in the pH. Salinity has less influence on stress sensitivity under acidic conditions. In terms of pH, which is bounded by critical salinity, a lower pH is beneficial for reservoir protection in low to intermediate salinity conditions. In contrast, when the pH is higher, the reservoir is better protected. Acidic conditions involve inorganic chemical reactions, whereas alkaline conditions involve organic-inorganic reactions, and the influence of salinity on permeability sensitivity is affected by the amount of H + .

show abstract

Effects of geological pressure and temperature on permeability behaviors of middle-low volatile bituminous coals in eastern Ordos Basin, China

Cited by 41 publications

References 36 publications

Variable Pore Structure and Gas Permeability of Coal Cores after Microwave Irradiation

Variable Pore Structure and Gas Permeability of Coal Cores after Microwave Irradiation

In-Situ Stress Measurements and Stress Accumulation Level Analysis of Coal Mines in Northern Ordos Basin

Study on stress sensitivity of lignite reservoir under salinity and pH composite system

Contact Info

Product

Resources

About