scholarly journals A Thermo-Hydro-Mechanical-Chemical Coupling Model and Its Application in Acid Fracturing Enhanced Coalbed Methane Recovery Simulation

Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 626 ◽  
Author(s):  
Chaojun Fan ◽  
Mingkun Luo ◽  
Sheng Li ◽  
Haohao Zhang ◽  
Zhenhua Yang ◽  
...  

The reservoir permeability dominates the transport of gas and water in coal seam. However, coal seams rich in gas usually contain various pores and fractures blocked by a large amount of minerals, which leads to an ultra-low permeability and gas extraction rate, and thus an increase of drilling workload. We first propose a thermo-hydro-mechanical-chemical coupled model (THMC) for the acid fracturing enhanced coalbed methane recovery (AF-ECBM). Then, this model is applied to simulate the variation of key parameters during AF-ECBM using a 2D geometry. The effect of different extraction schedules are comparatively analyzed to give an insight into these complex coupling responses in coal seam. Result confirms that the AF-ECBM is an effective way to increase the reservoir permeability and improve the gas production using the proposed model. The range of permeability increment zone increases most dramatically in the way of acid fracturing, followed by none-acid fracturing and acidizing over time. The gas production in order is: acid fracturing (AF-ECBM) > fracturing (F-ECBM) > acidification (A-ECBM)> direct extraction (D-CBM).

2011 ◽  
Vol 29 (6) ◽  
pp. 759-775 ◽  
Author(s):  
Fengde Zhou ◽  
Guangqing Yao ◽  
Zhonghua Tang ◽  
Oyinkepreye D. Orodu

Matrix compressibility, shrinkage and swelling can cause profound changes in porosity and permeability of coalbed during gas sorption and desorption. These factors affect the distribution of pressure, methane production and CO2 sequestration. This paper compares the effects of cleat compression and matrix shrinkage and swelling models with the injection of different compositional gas mixtures (CO2 and N2). It shows that well performance, pressure distribution and properties of the seam are strongly affected by matrix shrinkage and swelling. Matrix shrinkage and swelling also affects net present value of the enhanced coalbed methane recovery scheme. In order to select the best enhanced coalbed methane recovery schemes, economic evaluation and sensitivity studies are necessary.


Energy ◽  
2019 ◽  
Vol 173 ◽  
pp. 1054-1077 ◽  
Author(s):  
Chaojun Fan ◽  
Derek Elsworth ◽  
Sheng Li ◽  
Lijun Zhou ◽  
Zhenhua Yang ◽  
...  

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