An experimental study on permeability characteristics of coal with slippage and temperature effects

Li, Bobo; Yang, Kailun; Xu, Peng; Xu, Jiang; Mei, Yuan; Zhang, Min

doi:10.1016/j.petrol.2018.12.048

Cited by 47 publications

(21 citation statements)

References 51 publications

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“…The relative permeability models of Equations (A26) and (A27) at saturation S w are widely used [62]. Calibrating the endpoint relative permeability for gas slippage, a dynamic effective permeability model may be expressed as [63][64][65]:…”

Section: Governing Equation Of the Mechanical Fieldmentioning

confidence: 99%

Evolution of Production and Transport Characteristics of Steeply-Dipping Ultra-Thick Coalbed Methane Reservoirs

et al. 2020

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The large spatial variability of in-situ stress and initial reservoir pressure in steeply-dipping ultra-thick coalbed methane (UTCBM) reservoirs exert strong control on the initial distribution of stress-sensitive permeability. This results in significant differences in the propagation of reservoir depressurization, gas production characteristics, distribution of fluid saturation, and evolution of permeability relative to flat-lying and thin counterpart coalbed methane (CBM) reservoirs. We contrast these responses using the Fukang mining area of the Junggar Basin, Xinjiang, China, as a type-example using coupled hydro-mechanical modeling. Production response indicates: (1) Dual peaks in CBM production rate, due to the asynchronous changes in the gas production rate in each the upper and lower sections of the reservoir; (2) higher depressurization and water saturation levels in the lower section of the reservoir relative to the upper at any given distance from the production well that ameliorate with time to be similar to those of standard horizontal reservoirs; (3) the heterogeneity in effective stress is further amplified by the asymmetry of the initial pressure drawdown distribution of the reservoir to exert extreme control on the down-dip evolution of absolute permeability—with implications for production. Field drainage data and simulation results obtained in this study more accurately reflect the drainage characteristics of the steeply-dipping UTCBM reservoirs. For ultra-thick low-rank coal seams, permeability anisotropy plays an important role in determining the utility of horizontal wells and hydraulic fracturing to maximize rates and yields CBM production, and requiring further study.

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Section: Governing Equation Of the Mechanical Fieldmentioning

confidence: 99%

Evolution of Production and Transport Characteristics of Steeply-Dipping Ultra-Thick Coalbed Methane Reservoirs

et al. 2020

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“…During CBM drainage, the desorption effect is considered to enlarge the fractures and pores in the coal, thereby resulting in an increase in the permeability, and the desorption process is an endothermic process. The permeability decreases due to the closure of cleats and pores under the effect of the effective stress, and the strain increases. Therefore, the laws of reservoir deformation and temperature change can characterize the changes in permeability.…”

Section: Resultsmentioning

confidence: 99%

Different adsorbed gas effects on the reservoir parameters and production in coalbed methane extraction by multibranch horizontal wells

Peng

Yan

et al. 2019

Energy Science & Engineering

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Coalbed methane (CBM) is an efficient energy source that mainly contains CH4 and CO2. Multibranch horizontal wells (MBHWs) are widely used in CBM extraction. In the study, CH4 and CO2 were employed to perform CBM extraction experiments by MBHWs. Based on the experiments, a phenomenon occurs wherein gas from the high‐pressure production layer enters the low‐pressure production layer during the initial stage. Reservoir pressure, temperature, permeability, and instantaneous flow rate exhibit similar evolution laws. Specifically, they initially increase sharply, then declining rapidly, and finally level off in the production layer with the minimum initial pressure. Increase in the adsorption capacity lowers the increase in reservoir pressure, although the phenomenon persists longer from appearance to disappearance. The moment of permeability recovery is related to the adsorption capacity, and the moment of permeability recovery under CO2 conditions occurs after that under CH4 conditions. The instantaneous flow rate curve is divided into three categories, namely steep flow rate increase curve, flow rate inhibition curve, and backflow curve. The results are useful for CBM extraction of multiple coal seams.

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“…where R 1 is the difference, m; k is the slope. After calculation, the slope is 0.12, so the modified equation is shown in Equation (22).…”

Section: Stress In the Elasticmentioning

confidence: 99%

“…Therefore, to prevent coal and gas outburst in the coal mining process, gas drainage, high-pressure water injection hydraulic fracturing, mine ventilation dilution gas, protective coal mining, and other technical measures are usually adopted in coal mines, among which gas drainage is the most commonly used method [16][17][18][19]. In some high-gas-content mines in South China, drilling through the layer is often performed to control gas disasters [20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Optimization of the Plastic Area of a Borehole Based on the Gas Extraction Effect and Its Engineering Application

Shi

Lü

et al. 2021

Geofluids

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Gas extraction is most commonly used to control gas disasters in coal mines. The distribution of the plastic zone around a borehole and the sealing quality are key factors affecting gas extraction. In this paper, the plastic zone was simulated by COMSOL, and a theoretical equation of the plastic zone radius was derived. In addition, an antispray hole equipment and the “two plugging and one injection” sealing technology were proposed. The results show that a larger borehole pore size corresponds to a larger plastic zone and larger range of pressure relief of the borehole. The error between the calculated and simulated plastic zone radii is within 1%, and the modified equation is applicable to Puxi mine. The loss and harm caused by borehole spraying are reduced by applying antispray hole equipment. By applying the “two plugging and one injection” sealing technology and phosphogypsum-based self-produced gas expansion paste material to block the borehole, the sealing quality is improved and an accurate gas mixing flow, pure flow, and concentration were obtained. As the plastic zone enlarges, the gas extraction flow gradually increases with, but the relative variation of flow first increases and subsequently decreases. Considering the safety and economy of construction, the optimal radius of the plastic zone is 64.9 mm.

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An experimental study on permeability characteristics of coal with slippage and temperature effects

Cited by 47 publications

References 51 publications

Evolution of Production and Transport Characteristics of Steeply-Dipping Ultra-Thick Coalbed Methane Reservoirs

Evolution of Production and Transport Characteristics of Steeply-Dipping Ultra-Thick Coalbed Methane Reservoirs

Different adsorbed gas effects on the reservoir parameters and production in coalbed methane extraction by multibranch horizontal wells

Optimization of the Plastic Area of a Borehole Based on the Gas Extraction Effect and Its Engineering Application

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