Permeability and volumetric changes in coal under different test environment

Aziz, Naj; Ren, Ting X; Nemcik, Jan; Zhang, Lei

doi:10.13168/agg.2013.0016

Cited by 8 publications

(5 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The current operating seam is the Bulli seam, which is stratigraphically the uppermost seam in the Illawarra coal measures, of the Sydney Basin, which belong to Permian and Triassic era Aziz et al, 2013). The Bulli coal is high quality coking coal with volatile matters ranging from 18-23% (air dried), the ash level varies between 8-10% (air dried), and the sulphur content is low at around 0.3%, the mineral content averages around 4% (Aziz et al, 2013). The vitrinite content is moderate at 45%, the inertinite content is about 50% and vitrinite reflectance at around 1.3 (Saghafi & Roberts, 2008;Aziz et al, 2013).…”

Section: Geological Backgroundmentioning

confidence: 99%

“…The Bulli coal is high quality coking coal with volatile matters ranging from 18-23% (air dried), the ash level varies between 8-10% (air dried), and the sulphur content is low at around 0.3%, the mineral content averages around 4% (Aziz et al, 2013). The vitrinite content is moderate at 45%, the inertinite content is about 50% and vitrinite reflectance at around 1.3 (Saghafi & Roberts, 2008;Aziz et al, 2013). The permeability of the coal varies between 0.5 to 6.0 mD, determined both in situ and in the laboratory (Lingard et al, 1982;Sereshki, 2005;Black, 2012;Zhang, 2013).…”

Section: Geological Backgroundmentioning

confidence: 99%

See 1 more Smart Citation

Nitrogen Injection To Flush Coal Seam Gas Out Of Coal: An Experimental Study

Zhang

Aziz

Ren

et al. 2015

Archives of Mining Sciences

Self Cite

View full text Add to dashboard Cite

Several mines operating in the Bulli seam of the Sydney Basin in NSW, Australia are experiencing difficulties in reducing gas content within the available drainage lead time in various sections of the coal deposit. Increased density of drainage boreholes has proven to be ineffective, particularly in sections of the coal seam rich in CO 2 . Plus with the increasing worldwide concern on green house gas reduction and clean energy utilisation, significant attention is paid to develop a more practical and economical method of enhancing the gas recovery from coal seams. A technology based on N 2 injection was proposed to flush the Coal Seam Gas (CSG) out of coal and enhance the gas drainage process. In this study, laboratory tests on CO 2 and CH 4 gas recovery from coal by N 2 injection are described and results show that N 2 flushing has a significant impact on the CO 2 and CH 4 desorption and removal from coal. During the flushing stage, it was found that N 2 flushing plays a more effective role in reducing adsorbed CH 4 than CO 2 . Comparatively, during the desorption stage, the study shows gas desorption after N 2 flushing plays a more effective role in reducing adsorbed CO 2 than CH 4 . Keywords: N 2 injection, coal seam gas, coal, gas composition, gas volume W kilku kopalniach eksploatujących złoże Bulli w zagłębiu węglowym Sydney w Nowej Południo-wej Walii w Australii pojawił się problem redukcji zawartości gazu kopalnianego w złożach zawartego w różnych częściach złoża, w określonym czasie. Zwiększenie gęstości wykonywania odwiertów drenażowych okazało się być metodą nieskuteczną, zwłaszcza w częściach złoża bogatego w CO 2 . Inne kwestie to wzrastająca w świecie świadomość konieczności redukcji gazów cieplarnianych i wykorzystania czystej energii, stąd też podejmowane wysiłki na rzecz opracowania praktycznych i ekonomicznych metod odzyskiwania gazu ze złóż węgla. W pracy przedstawiono technologię opartą na wprowadzaniu azotu do złoża w celu wypłukania gazu zawartego w węglu, poprawiając skuteczność ich odzyskiwania. W prowadzonych pracach badano skuteczność odzysku CO 2 i metanu ze złoża węgla po wprowadzeniu Słowa kluczowe: wprowadzanie azotu do złoża, gaz zawarty w węglu, węgiel, skład gazu, objętość gazu

show abstract

Section: Geological Backgroundmentioning

confidence: 99%

Section: Geological Backgroundmentioning

confidence: 99%

Nitrogen Injection To Flush Coal Seam Gas Out Of Coal: An Experimental Study

Zhang

Aziz

Ren

et al. 2015

Archives of Mining Sciences

Self Cite

View full text Add to dashboard Cite

show abstract

“…More than 70% of coal-bearing strata in China are low-permeability coal seams, and their gas permeability is generally 0.1~10 md (2-3 orders of magnitude different from that of the Black Warriors Basin in the United States) [1][2][3][4][5]. In addition, gas is free in the coal seam fracture system, and exists in the adsorption state on the pore and fracture surface.…”

Section: Introductionmentioning

confidence: 99%

Study on Crack Penetration Induced by Fatigue Damage of Low Permeability Coal Seam under Cyclic Loading

2022

View full text Add to dashboard Cite

For low permeability coal seam permeability is weak, low degree of gas migration, prone to gas accidents and other issues. In this paper, a numerical model is established to simulate the process of hydraulic fracturing under monotonic loading and cyclic loading, and a method of increasing permeability of coal seam by cyclic loading hydraulic fracturing technology is proposed. Combined with similar experiments, the influence of cyclic load and cyclic load applied parameters on the fracturing effect of coal and rock mass was analyzed by applying a cyclic load with a pulse pump. The effect of cyclic load pressure technology on coal seam drainage was analyzed by application in 20915 gas control roadways of a coal mine in Guizhou. The results show that after fracturing, the fracture extends along the weak plane of the prefabricated fracture, the pore pressure in the fracture is high pressure, and the pore pressure around the fracture decreases step by step. Due to the compression of the crack, the energy is transferred to the two ends of the crack. The pore pressure has an irregular oval distribution, and there is stress concentration. The pressure value reaches 41.48 MPa. After the cyclic load was applied to the model, the pressure reached the maximum value of 27.64 MPa at 3.37 s. Compared with the monotonic load, the pressure value was reduced by 46.27%. Through pressure and ringing analysis, the fatigue damage of specimens can be realized under cyclic loading. In the experiment, the unconstrained initiation pressure was 2.48 MPa, but after the constraint was applied, the initiation pressure increased to 4.58 MPa, and the pressure increase reached about 55%. After multiple loading and unloading, the peak pressure of the specimen can be reduced and the number of cracks can be increased. In the experiment, the gas extraction rate of ordinary drilling was maintained at about 0.019 m3/min, and the gas extraction rate of ordinary fracturing drilling fluctuated at 0.025 m3/min after 21 days of gas extraction. The pumping capacity of 15 Hz and 20 Hz cyclic loading fracturing boreholes tended to be stable after 15 days, which were about 0.041 m3/min and 0.062 m3/min, respectively. Cyclic loading hydraulic fracturing is better than monotonic loading hydraulic fracturing, and the lower the cyclic loading frequency, the better the fracturing effect.

show abstract

“…At present, the main solution to this problem is to strengthen and enhance the outburst seam to improve the gas drainage results of the coal seam. In recent years, the ground vertical well with hydraulic fracturing technology, as a kind of improving permeability technology, has been widely applied to the development of coalbed methane, achieving good results in some non-geostructural zones (Aziz et al., 2013; Guo et al., 2012; Huang et al., 2011; Huang and Li, 2015; Keshavarz et al., 2016; Ren et al., 2017; Saghafi, 2014; Yuan et al., 2012). This offers a new technical approach to enhance the gas drainage in coal seams in the geostructural belts.…”

Section: Introductionmentioning

confidence: 99%

The case for enhanced coalbed methane using hydraulic fracturing in the geostructural belt

Sun

et al. 2018

Energy Exploration & Exploitation

View full text Add to dashboard Cite

Coal and gas outbursts mostly occur during mining at geostructural belts. Pre-drainage coalbed methane using hydraulic fracturing is one of the methods to prevent outbursts. However, the coal in geostructural belts is to be soft and crushed with special mechanical properties and pore structure. To explore the feasibility of hydraulic fracturing in geostructural belts, a field investigation on enhanced coalbed methane using hydraulic fracturing with vertical well was conducted at the Yangquan Coalfield, China. This case puts forward a method for the location selection of vertical well in geostructural belts. In addition, a triple-control technology for hydraulic fracturing, which is characterized by pressure control, flow control and sand ratio control of fracturing fluid, is presented. The results show that the average gas production and maximum gas drainage capacity of the test well were 5.67 and 12.88 times than those of the regular well, respectively, achieving good drainage effects.

show abstract

Permeability and volumetric changes in coal under different test environment

Cited by 8 publications

References 8 publications

Nitrogen Injection To Flush Coal Seam Gas Out Of Coal: An Experimental Study

Nitrogen Injection To Flush Coal Seam Gas Out Of Coal: An Experimental Study

Study on Crack Penetration Induced by Fatigue Damage of Low Permeability Coal Seam under Cyclic Loading

The case for enhanced coalbed methane using hydraulic fracturing in the geostructural belt

Contact Info

Product

Resources

About