Influence of Engineering Measurements on the Desorption and Production of CBM Wells by Eclipse

2013 ◽  
Vol 868 ◽  
pp. 700-704 ◽  
Author(s):  
Rui Wang ◽  
Fan Dong ◽  
Qing Zhong Zhu ◽  
Yan Hui Yang ◽  
Tian Peng Yao
Keyword(s):  
Coalbed Methane ◽  
Production Capacity ◽  
Gas Production ◽  
Simulation Software ◽  
Stage Of Development ◽  
Cbm Production ◽  
Stable Yield ◽  
Yield Time ◽  
Coal Reservoir ◽  
The Impact

Desorption of Coalbed Methane is one of the key controls to CBM recovery ratio and production capacity. This paper discusses the impact of engineered measures on CBM overall desorption and production capacity with CBM model of Eclipse numerical simulation software. The simulation results show that: with the extension of hydraulic fracture half-length, overall desorption of coal reservoir increased and CBM production capacity improved, daily gas production, maximum gas production and stable yield time increased correspondingly; in different deployment of spacing and well network, the smaller spacing is beneficial to the overall desorption of coal reservoir, but its production can not keep stability because of the serious decline in the late stage of development, while the larger spacing shows in the opposite way.

scholarly journals A Comprehensive Coal Reservoir Classification Method Base on Permeability Dynamic Change and Its Application

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 644 ◽  
Author(s):  
Xinlu Yan ◽  
Songhang Zhang ◽  
Shuheng Tang ◽  
Zhongcheng Li ◽  
Yongxiang Yi ◽  
...  
Keyword(s):  
Coalbed Methane ◽  
Dynamic Change ◽  
Initial Permeability ◽  
Gas Production ◽  
Gas Desorption ◽  
Reservoir Permeability ◽  
Geological Conditions ◽  
Production Stages ◽  
Productivity Potential ◽  
Coal Reservoir

Due to the unique adsorption and desorption characteristics of coal, coal reservoir permeability changes dynamically during coalbed methane (CBM) development. Coal reservoirs can be classified using a permeability dynamic characterization in different production stages. In the single-phase water flow stage, four demarcating pressures are defined based on the damage from the effective stress on reservoir permeability. Coal reservoirs are classified into vulnerable, alleviative, and invulnerable reservoirs. In the gas desorption stage, two demarcating pressures are used to quantitatively characterize the recovery properties of permeability based on the recovery effect of the matrix shrinkage on permeability, namely the rebound pressure (the pressure corresponding to the lowest permeability) and recovery pressure (the pressure when permeability returns to initial permeability). Coal reservoirs are further classified into recoverable and unrecoverable reservoirs. The physical properties and influencing factors of these demarcating pressures are analyzed. Twenty-six wells from the Shizhuangnan Block in the southern Qinshui Basin of China were examined as a case study, showing that there is a significant correspondence between coal reservoir types and CBM well gas production. This study is helpful for identifying geological conditions of coal reservoirs as well as the productivity potential of CBM wells.

scholarly journals Analysis of hydraulic fracture behavior and well pattern optimization in anisotropic coal reservoirs

2020 ◽  
pp. 014459872096083
Author(s):  
Yulong Liu ◽  
Dazhen Tang ◽  
Hao Xu ◽  
Wei Hou ◽  
Xia Yan
Keyword(s):  
Hydraulic Fracture ◽  
Coalbed Methane ◽  
Fracture Network ◽  
Simulation Software ◽  
Natural Fracture ◽  
Hydraulic Fractures ◽  
Natural Fractures ◽  
Well Pattern ◽  
Well Pattern Optimization ◽  
The Impact

Macrolithotypes control the pore-fracture distribution heterogeneity in coal, which impacts stimulation via hydrofracturing and coalbed methane (CBM) production in the reservoir. Here, the hydraulic fracture was evaluated using the microseismic signal behavior for each macrolithotype with microfracture imaging technology, and the impact of the macrolithotype on hydraulic fracture initiation and propagation was investigated systematically. The result showed that the propagation types of hydraulic fractures are controlled by the macrolithotype. Due to the well-developed natural fracture network, the fracture in the bright coal is more likely to form the “complex fracture network”, and the “simple” case often happens in the dull coal. The hydraulic fracture differences are likely to impact the permeability pathways and the well productivity appears to vary when developing different coal macrolithtypes. Thus, considering the difference of hydraulic fracture and permeability, the CBM productivity characteristics controlled by coal petrology were simulated by numerical simulation software, and the rationality of well pattern optimization factors for each coal macrolithotype was demonstrated. The results showed the square well pattern is more suitable for dull coal and semi-dull coal with undeveloped natural fractures, while diamond and rectangular well pattern is more suitable for semi-bright coal and bright coal with more developed natural fractures and more complex fracturing fracture network; the optimum wells spacing of bright coal and semi-bright coal is 300 m and 250 m, while that of semi-dull coal and dull coal is just 200 m.

scholarly journals Quantitative optimization of drainage strategy of coalbed methane well based on the dynamic behavior of coal reservoir permeability

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Xinlu Yan ◽  
Songhang Zhang ◽  
Shuheng Tang ◽  
Zhongcheng Li ◽  
Qian Zhang ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Dynamic Behavior ◽  
Water Flow ◽  
Coalbed Methane ◽  
Single Phase ◽  
Reservoir Permeability ◽  
Geological Conditions ◽  
Cbm Production ◽  
Coal Reservoir ◽  
Flow Stage

AbstractThe development of coalbed methane (CBM) is not only affected by geological factors, but also by engineering factors, such as artificial fracturing and drainage strategies. In order to optimize drainage strategies for wells in unique geological conditions, the characteristics of different stages of CBM production are accurately described based on the dynamic behavior of the pressure drop funnel and coal reservoir permeability. Effective depressurization is achieved by extending the pressure propagation radius and gas desorption radius to the well-controlled boundary, in the single-phase water flow stage and the gas–water flow stage, respectively, with inter-well pressure interference accomplished in the single-phase gas flow stage. A mathematic model was developed to quantitatively optimize drainage strategies for each stage, with the maximum bottom hole flow pressure (BHFP) drop rate and the maximum daily gas production calculated to guide the optimization of CBM production. Finally, six wells from the Shizhuangnan Block in the southern Qinshui Basin of China were used as a case study to verify the practical applicability of the model. Calculation results clearly indicate the differences in production characteristics as a result of different drainage strategies. Overall, if the applied drainage strategies do not achieve optimal drainage results, the coal reservoir could be irreversibly damaged, which is not conducive to expansion of the pressure drop funnel. Therefore, this optimization model provides valuable guidance for rational CBM drainage strategy development and efficient CBM production.

Impact of Various Parameters on the Production of Coalbed Methane

SPE Journal ◽  
2013 ◽  
Vol 18 (05) ◽  
pp. 910-923 ◽  
Author(s):  
Zhongwei Chen ◽  
Jishan Liu ◽  
Akim Kabir ◽  
Jianguo Wang ◽  
Zhejun Pan
Keyword(s):  
Time Constant ◽  
Coalbed Methane ◽  
Dominant Role ◽  
Gas Production ◽  
Fracture Permeability ◽  
Permeability Model ◽  
Gas Desorption ◽  
Desorption Time ◽  
Matrix Blocks ◽  
Cbm Production

Summary Coalbed-methane (CBM) reservoirs are naturally fractured formations, comprising both permeable fractures and matrix blocks. The interaction between fractures and matrix presents a great challenge for the forecast of CBM reservoir performance. In this work, a dual-permeability model was applied to study the parameter sensitivity on the CBM production, because the dual-permeability model incorporates not only the influence from matrix and fractures but also that between adjacent matrix blocks. The mass exchange between two systems is defined as a function of desorption time constant at the standard condition, coal matrix porosity, and the difference of gas pressure between two systems. Correspondingly, gas diffusivity in matrix is considered as a variable and represented by a function of shape factor, gas desorption time, and reservoir pressure. These relations are integrated into a fully coupled numerical model of coal geomechanical deformation and gas desorption/gas flow in both systems. This numerical approach demonstrates the important nonlinear effects of the complex interaction between matrix and fractures on CBM production behaviors that cannot be recovered without rigorously incorporating geomechanical influences. This model was then used to investigate the sensitivity of CBM extraction behavior to different controlling factors, including gas desorption time constant, initial fracture permeability, fracture spacing, swelling capacity, desorption capacity, production pressure, and fracture and matrix porosities. Modeling results show that the peak magnitudes of gas-production rate increase with initial fracture permeability, sorption and swelling capacities, and matrix porosity, and decrease with gas desorption time constant and production pressure. These results also show dramatic increase in gas-production efficiency with decreasing magnitudes of fracture spacing. The comparison of the transient contributions of the desorbed gas and the free phase gas from the matrix system to gas production shows that the free phase gas plays the dominant role at the early stage, but diminishes when the adsorption phase gas takes over the dominant role, indicating the necessity of incorporating free phase gas impact in simulation models. The numerical model was also applied to match the history data from a gas-production well. A better matching result than that for the single-permeability model demonstrates the potential capability of the dual-permeability model for the forecast of CBM production.

scholarly journals Microbial Simulation Experiment on Enhancing Coalbed Methane Production

2019 ◽  
Author(s):  
Chen Hao ◽  
Qin Yong ◽  
Zhou Shangwen ◽  
Wang Hongyan ◽  
Chen Zhenhong ◽  
...  
Keyword(s):  
Methane Production ◽  
Coalbed Methane ◽  
Simulation Experiment ◽  
Bacterial Species ◽  
Gas Production ◽  
Gas Generation ◽  
Exogenous Bacteria ◽  
Different Temperatures ◽  
Cbm Production ◽  
Coalbed Methane Production

Coalbed Methane(CBM) production enhancement for single wells is a big problem to CBM industrialization. Low production is due to insufficient gas generation by thermogenic. Luckily, Biogenic gas was found in many areas and its supply is assumed to improve coalbed methane production. Therefore, microbial simulation experiment will demonstrate the effectiveness of the assumption. From microbial simulation experiment on different coal ranks, it is found that microbes can use coals to produce biogas under laboratory conditions. With different temperatures for different experiments, it turns out that the gas production at 35 ℃ is greater than that at 15℃,indicating that 35℃ is more suitable for microbes to produce gas. According to quantitative experiments, adding exogenous nutrients or exogenous bacteria can improve CBM production. Moreover, the production enhancement ratio can reach up to 115% under the condition of adding exogenous bacterial species, while the ratio for adding nutrients can be up to 144%.

scholarly journals Coupled flow-geomechanics studies on the role of hydrofracturing and secondary fracturing in CO2-enhanced coalbed methane

2021 ◽  
pp. 014459872098527
Author(s):  
Chaobin Guo ◽  
Quanlin Feng ◽  
Tianran Ma ◽  
Siqi Wang ◽  
Rui Zhou ◽  
...  
Keyword(s):  
Coalbed Methane ◽  
Production Efficiency ◽  
Gas Production ◽  
Simulation Software ◽  
Fracture Density ◽  
Coupled Flow ◽  
Injection Wells ◽  
Mechanical Coupling ◽  
Fracturing Process ◽  
Enhanced Coalbed Methane

CO2-enhanced coalbed methane (CO2-ECBM) can improve coalbed methane production efficiency and simultaneously alleviate greenhouse gas emissions. In this paper, we integrated TOUGH2 and FLAC3D numerical simulation software to conduct hydro-mechanical coupling analysis for effects of hydrofracturing and secondary fracturing in CO2-ECBM. The simulation results show that the hydrofracturing and secondary fracturing treatments significantly increase the coal seam interconnectivity, enhancing overall injection and production. The reduction of the pore pressure near injection wells can effectively reduce the damage of gas injection well. Moreover, secondary fracturing can even increase cumulative gas production up to 32.5%. In addition to rising fracture density, increasing the fracture length is also considered an efficacious procedure for enhancing permeability in the secondary fracturing process.

scholarly journals Analysis on Production of Coal Bed Methane Considering the Change in Permeability of Coal Rock

2016 ◽  
Vol 9 (1) ◽  
pp. 289-298 ◽  
Author(s):  
Zhu Likai ◽  
Ji Youjun ◽  
Yang Tianhong ◽  
Li Xiaoyu
Keyword(s):  
Coal Mine ◽  
Confining Pressure ◽  
Gas Production ◽  
Coal Bed ◽  
Coal Bed Methane ◽  
Methane Extraction ◽  
Coal Rock ◽  
Cbm Production ◽  
Stable Yield ◽  
Set Up

Based on the mechanism of migration of the coal bed methane (CBM), and taking into account the deformation of the coal rock during the process of CBM production was also taken into account, a coupled mathematical model considering the interaction of solid and fluid for methane extraction was built. The coal gas extraction of JINcheng coal mine was taken as an example, some typical coal sample was chosen to test the permeability under different confining pressure. The curve for permeability of coal rock versus effective stress under different confining pressure was obtained, a numerical model considering the variation of permeability for methane extraction was set up. The influence of deformation of coal rock on the gas production was simulated and analyzed. The simulation results indicate that the productivity curve considering deformation of rock is closer to the actual production data, at the initial stage of production, the gas rate is less than the case without considering deformation of rock, but the time of stable yield will last longer, and this matches the actual methane extraction, therefore, we recommend that the deformation of coal seam should be considered during the prediction of methane production for JINcheng coal mine.

scholarly journals Numerical analysis of drainage rate for multilayer drainage coalbed methane well group in Southern Qinshui basin

2020 ◽  
Vol 38 (5) ◽  
pp. 1535-1558
Author(s):  
Qiujia Hu ◽  
Shiqi Liu ◽  
Shuxun Sang ◽  
Huihuang Fang ◽  
Ashutosh Tripathy ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Coal Seam ◽  
Coalbed Methane ◽  
Gas Production ◽  
Hydraulic Pressure ◽  
Qinshui Basin ◽  
Well Production ◽  
Drainage Rate ◽  
Southern Qinshui Basin ◽  
Cbm Production

Multilayer drainage is one of the important technologies for coalbed methane (CBM) production in China. In this study, a multi-field fully coupled mathematical model for CBM production was established to analyze the multilayer drainage of CBM well group in southern Qinshui basin. Based on the numerical simulation results, the characteristics of CBM well production under different drainage rates and key factors influencing the CBM production were further discussed. The results show that the effect of an increased drainage rate on gas production of CBM wells and CBM recovery of No.3 coal seam is not significant. However, it significantly improved the gas production of CBM wells and CBM recovery of No.15 coal seam. After a long period of production, the CBM content in No.3 coal seam has reduced to a low level and the pressure drop potential of No.3 coal seam is insignificant, which are important reasons for the insignificant increase of CBM production even under a drainage rate of 2 to 7 times. Conversely, No.15 coal seam has larger residual CBM content and increasing the drainage rate can significantly improve the pressure drop and superimposed well interference of No.15 coal seam, which means No.15 coal seam has greater production potential than No.3 coal seam. Therefore, it is recommended to improve the gas production and CBM recovery in No.15 coal seam by increasing the drainage rate, and the average hydraulic pressure drop should be 0.018–0.031 MPa/day. The influence of effective stress is weak in No.3 and No.15 coal seam, and the coal seam permeability is largely influenced by the shrinkage of coal matrix caused by CBM desorption. This indicates the feasibility of increase in gas production from CBM wells by increasing the drainage rate.

scholarly journals Analysis of productivity differences in vertical coalbed methane wells in the Shizhuangnan Block, Southern Qinshui Basin, and their influencing factors

2020 ◽  
Vol 38 (5) ◽  
pp. 1428-1453 ◽  
Author(s):  
Xinlu Yan ◽  
Shuheng Tang ◽  
Songhang Zhang ◽  
Yongxiang Yi ◽  
Feng Dang ◽  
...  
Keyword(s):  
Coalbed Methane ◽  
Impact Analysis ◽  
Production Capacity ◽  
High Water ◽  
Water Production ◽  
Correlation Degree ◽  
Reservoir Conditions ◽  
External Water ◽  
Grey Relational ◽  
The Impact

Coalbed methane wells in the Shizhuangnan Block exhibit significant productivity differences. The reasons were determined based on the impact analysis of geological factors and drainage strategies on production capacity at 82 wells. Grey relational analysis was further utilized to quantitatively analyze the correlation degree of geological parameters to production characteristics. It is found that the main reason for wells with high water production is the ingress of external water, i.e. connecting adjacent aquifer by natural faults or artificial fractures. And aquifer characteristics, especially thickness of aquifer has the greatest influence on the water production, followed by pore connectivity, porosity, and shale content. For the wells that have not been affected by external water, the gas productivity differences are mainly affected by reservoir conditions and drainage strategies. Finally, an analytical process was proposed to provide theoretical support for rational production of coalbed methane wells.

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

Energies ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 5081 ◽  
Author(s):  
Shun Liang ◽  
Hao Han ◽  
Derek Elsworth ◽  
Xuehai Fu ◽  
Qiangling Yao ◽  
...  
Keyword(s):  
Production Rate ◽  
Coalbed Methane ◽  
Water Saturation ◽  
Initial Pressure ◽  
Gas Production ◽  
Low Rank ◽  
Absolute Permeability ◽  
Fluid Saturation ◽  
Cbm Production ◽  
Strong Control

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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