Productivity equation of fractured well in CBM reservoirs

Lou, Yu; Song, Hongqing; Yang, Jian; Huang, Xiaofeng; Dong, He

doi:10.1016/j.jngse.2012.12.001

Cited by 23 publications

(6 citation statements)

References 18 publications

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“…The permeability, ratio of critical desorption pressure to reservoir pressure (RCR), and gas content are ultimately selected as the key static parameters for well type classification due to their relatively high correlation with gas production. Considering that the key dynamic parameters of CBM wells in existing studies usually include gas production, pressure and permeability (Yuanyuan et al, 2012;Lou et al, 2013;Chen et al, 2015;Fu et al, 2017;Bao et al, 2020), this paper selects average daily gas production, average reservoir pressure drop, and change amplitude of permeability as dynamic parameters. The average reservoir pressure drop and dynamic permeability are derived from the mathematical model established in the preceding section.…”

Section: Classification Of Cbm Wells Based On Som Neural Networkmentioning

confidence: 99%

“…CBM, characterized by its non-toxic combustion, absence of particulate matter emissions, and lower carbon dioxide release compared to coal, oil, or wood, is acknowledged as a clean fuel (Chen et al, 2017;Peng et al, 2017;Kong et al, 2022;Ni et al, 2023). Over the past 2 decades, CBM has emerged as a significant energy resource and is anticipated to play a pivotal role in meeting future global energy demands (Moore, 2012;Lou et al, 2013;Fu et al, 2017;Gao et al, 2023a;Ifrene et al, 2023;Wang et al, 2024a). China, as the current global leader in coal consumption and production, can benefit from the development of CBM resources.…”

Section: Introductionmentioning

confidence: 99%

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Production characteristics and influencing factors of coalbed methane wells: a case study of the high-ranking coal seam in the southeastern Qinshui Basin, China

Chen,

Gao,

Wang

2024

Front. Earth Sci.

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This study focuses on coalbed methane (CBM) wells in high-ranking coal seam as the research subject. Considering the influence of effective stress and matrix shrinkage, a comprehensive permeability calculation model for CBM reservoirs is established. Based on this model, the variations in pressure and permeability during well production are quantified. By integrating static geological parameters, a finely classified classification of CBM wells is achieved using self-organizing map (SOM) neural network. Subsequently, an analysis of production dynamic characteristics and productivity differences among different types of CBM wells is performed, followed by providing drainage optimization suggestions. The results of SOM analysis show that 7,000 m3/d and 1,500 m3/d can be used as the production boundaries for the wells with different productivity in Block P. The daily gas production of exceptional well exceeds 7,000 m3/d, and the permeability remains relatively stable throughout the drainage process of this well. The daily gas production of the potential well ranges from 1,500 to 7,000 m3/d, and the permeability exhibits a significant decrease during the drainage process. The daily gas production of Inefficient well is consistently below 1,500 m3/d with moderate permeability variation. In addition to well location and structural geology, production variability is also influenced by the matching of reservoir conditions and drainage systems. This is primarily manifested in discontinuous drainage systems and rapid decline in bottom hole pressure (BHP) during early production. The analysis of drainage parameters indicates that in order to achieve optimal production from CBM wells, the BHP should exhibit an initial rapid decline followed by a slowly decrease during the early production period, with an average pressure drop ranging from 0.005 to 0.02 MPa/d. The research findings can offer technical guidance for the future advancement of CBM in the P Block.

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Section: Classification Of Cbm Wells Based On Som Neural Networkmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Production characteristics and influencing factors of coalbed methane wells: a case study of the high-ranking coal seam in the southeastern Qinshui Basin, China

Chen,

Gao,

Wang

2024

Front. Earth Sci.

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“…Based on Darcy’s law, the control equation of coal particles gas flowing can be obtained [39]: (1) u true⟶ = − k μ ∂ p ∂ x i true⟶ + ∂ p ∂ y j true⟶ + ∂ p ∂ z k true⟶ , where true u ⟶ is gas velocity (m/s), k expresses permeability of coal particles ( m 2 ), μ indicates gas viscosity coefficient and is 1.71 × 10 -5 (MPa· s ), and p displays gas pressure in coal particles (MPa).…”

Section: Theory and Modelmentioning

confidence: 99%

Selection of Characteristic Particle Size of Drilling Cuttings Based on Adsorption-Desorption Properties: Experiment and Simulation

2022

Adsorption Science & Technology

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The direct method for measuring gas content based on image processing, that is, comparing the desorption curves of drilling cuttings with the characteristic particle size with the desorption image in the database to determine the gas content of coal seams, can solve the problems of long measurement time and larger measurement errors of the traditional direct method. However, the precondition to realize this method is to define the characteristic particle size of drilling cuttings. Therefore, this paper performed adsorption and desorption experiments under different particle size ranges and dissimilar adsorption equilibrium pressures, solved the gas migration control equation in coal particles, and determined the characteristic particle size from experimental results and simulation effect. The results showed that gas desorption quantity was positively correlated with adsorption equilibrium pressure, while negatively correlated with the size of a particle size range. The greater the adsorption equilibrium pressure, the better the linear fitting relationship with the maximum desorption quantity, and the maximum correlation coefficient could reach 0.9658. Based on Darcy’s law, Langmuir adsorption equation, and mass conservation law, the theoretical control equation of gas migration in coal particles was derived and solved by Open source Field Operation and Manipulation (OpenFOAM). The accuracy of the calculation results of the solver was verified by the derived analytical solution of the gas pressure change of coal particles without considering the adsorption. From the experimental results and simulation results, the characteristic particle size of drilling cuttings was determined to be 0.5-1 mm. The research can provide help for the subsequent development of direct gas content measurement technology based on image processing.

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“…With the fracture direction as x axis direction, as shown in Fig. 1 , Cartesian coordinates, ( x ′, y ′) can be transformed into elliptical coordinates, using the following relationship: where and separately represents a family of confocal ellipses and a family of confocal hyperbolas with 2 L (length of fracture) as focal length (Lou et al 2013 ). Assume that the production rate in the elliptical area of the fractured vertical well will follow Darcy’s law: …”

Section: Mathematical Model and Analytical Solutionsmentioning

confidence: 99%

Analytical modeling of gas production rate in tight channel sand formation and optimization of artificial fracture

et al. 2016

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Permeability variation in tight channel sand formation makes an important role in gas production. Based on the features of channel sand formation, a mathematical model has been established considering anisotropy of permeability. The analytical solutions were derived for productivity of both vertical wells and vertically fractured wells. Simulation results show that, gas production rate of anisotropic channel sand formation is less than that of isotropic formation. For vertically fractured well, artificial fracture direction, drainage radius, permeability ratio and fracture half-length have considerable influence on production rate. The optimum fracture direction should be deviated less than π/8 from the maximum permeability direction (or the channel direction). In addition, the analytical model was verified by in situ measured data. The research provides theoretical basis for the development of tight channel sand gas reservoirs.

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Productivity equation of fractured well in CBM reservoirs

Cited by 23 publications

References 18 publications

Production characteristics and influencing factors of coalbed methane wells: a case study of the high-ranking coal seam in the southeastern Qinshui Basin, China

Production characteristics and influencing factors of coalbed methane wells: a case study of the high-ranking coal seam in the southeastern Qinshui Basin, China

Selection of Characteristic Particle Size of Drilling Cuttings Based on Adsorption-Desorption Properties: Experiment and Simulation

Analytical modeling of gas production rate in tight channel sand formation and optimization of artificial fracture

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